tellectual disability and of  a neurocognitive disorder may both be assigned.
Although intellectual disability is generally nonprogressive, in certain genetic disor-
ders (e.g., Rett syndrome) there are periods of worsening, followed by stabilization, and in


Intellectual Disability (Intellectual Developmental Disorder) 39
others (e.g., San Phillippo synd rome) progressive worsening of  intellectual function. After
early childhood, the disorder is generally lifelong, although severity levels may change
over time. The course may be influenced by underlying medical or genetic conditions and
co-occurring conditions (e.g., hearing or visual impairments, epilepsy). Early and ongoing in-
terventions may improve adap tive functioning throughout  childhood and adulthood. In
some cases, these result in significant improve ment of intellectual functioning, such that
the diagnosis of intellectual disability is no lo nger appropriate. Thus, it is common practice
when assessing infants and young children to de lay diagnosis of intellectual disability un-
til after an appropriate course of intervention  is provided. For olde r children and adults,
the extent of support provided may allow for fu ll participation in all activities of daily liv-
ing and improved adaptive function. Diagnost ic assessments must determine whether im-
proved adaptive skills are the result of a st able, generalized new skill acquisition (in which
case the diagnosis of intellectual disability may no longer be appropriate) or whether the
improvement is contingent on the presence of supports and ongoing interventions (in
which case the diagnosis of intellectua l disability may still be appropriate).
Risk and Prognostic Factors
Genetic and physiological. Prenatal etiologies include genetic syndromes (e.g., se-
quence variations or copy number variants involving one or more genes; chromosomal
disorders), inborn errors of metabolism, brai n malformations, maternal disease (including
placental disease), and environmental influences (e.g., alcohol, other drugs, toxins, terato-
gens). Perinatal causes include a variety of labor and delivery-related events leading to


gens). Perinatal causes include a variety of labor and delivery-related events leading to
neonatal encephalopathy. Postnatal causes include hypoxic ischemic injury, traumatic
brain injury, infections, demyelinating disorder s, seizure disorders (e .g., infantile spasms),
severe and chronic social deprivation, and toxic metabolic syndromes and intoxications
(e.g., lead, mercury).
Culture-Related Diagnostic Issues
Intellectual disability occurs in all races and cultures. Cultural sen sitivity and knowledge
are needed during assessment, and the individu al’s ethnic, cultural, and linguistic back-
ground, available experiences, and adaptive functioning within his or her community and
cultural setting must be taken into account.
Gender-Related Diagnostic Issues
Overall, males are more likely than female s to be diagnosed with both mild (average
male:female ratio 1.6:1) and severe (average male:female ratio 1.2:1) forms of intellectual
disability. However, gender ratios vary widely  in reported studies.  Sex-linked genetic fac-
tors and male vulnerability to brain insult ma y account for some of the gender differences.
Diagnostic Markers
A comprehensive evaluation includes an assess ment of intellectual capacity and adaptive
functioning; identification of  genetic and nongenetic etiolo gies; evaluation for associated
medical conditions (e.g., cerebral palsy, seiz ure disorder); and eval uation for co-occurring
mental, emotional, and behavior al disorders. Components of the evaluation may include
basic pre- and perinatal medical history, three- generational family pedigree, physical exam-
ination, genetic evaluation (e.g., karyotype or  chromosomal microarray  analysis and testing
for specific genetic syndromes), and metabo lic screening and neuroimaging assessment.
Differential Diagnosis


Differential Diagnosis
The diagnosis of intellectual disability should be  made whenever Criteria A, B, and C are
met. A diagnosis of intellectual disability should not be assumed because of a particular


40 Neurodevelopmental Disorders
genetic or medical condition. A genetic syndro me linked to intellec tual disability should
be noted as a concurrent diagnosi s with the intellectual disability.
Major and mild neurocognitive disorders. Intellectual disability is categorized as a neu-
rodevelopmental disorder and is distinct from the neurocognitive disorders, which are
characterized by a loss of cognitive function ing. Major neurocognitive disorder may co-
occur with intellectual disability (e.g., an individual with Down syndrome who develops
Alzheimer’s disease, or an individual with  intellectual disability who loses further cogni-
tive capacity following a head injury). In such cases, the diagnoses of intellectual disability
and neurocognitive disorder may both be given.
Communication disorders and specific learning disorder. These neurodevelopmental
disorders are specific to the communication and learning domains and do not show defi-
cits in intellectual an d adaptive behavior. They may co-o ccur with intellectual disability.
Both diagnoses are made if full criteria are met for intellectual disability and a communi-
cation disorder or specific learning disorder.
Autism spectrum disorder. Intellectual disability is common among individuals with
autism spectrum disorder. Assessment of intellectual ability may be complicated by so-
cial-communication and behavior deficits inherent to auti sm spectrum disorder, which
may interfere with understanding and comply ing with test procedures. Appropriate as-
sessment of intellectual functioning in autism spectrum disorder is essential, with reas-
sessment across the developmental period, becaus e IQ scores in auti sm spectrum disorder
may be unstable, particularly in early childhood.
Comorbidity
Co-occurring mental, neurodevelopmental, me dical, and physical conditions are frequent
in intellectual disability, with rates of some conditions (e.g., ment al disorders, cerebral


in intellectual disability, with rates of some conditions (e.g., ment al disorders, cerebral
palsy, and epilepsy) three to fo ur times higher than in the ge neral population. The prognosis
and outcome of co-occurring diagnoses may be influenced by the presence of intellectual
disability. Assessment procedur es may require modifications because of associated disor-
ders, including communication disorders, autism spectrum disorder, and motor, sensory,
or other disorders. Knowledgeable informan ts are essential for identifying symptoms
such as irritability, mood dysregulation, aggression, eating problems, and sleep problems,
and for assessing adaptive functioning in various community settings.
The most common co-occurring mental an d neurodevelopmental disorders are atten-
tion-deficit/hyperactivity disorder; depressi ve and bipolar disorders; anxiety disorders;
autism spectrum disorder; stereotypic movement d isorder (with or without self-injurious
behavior); impulse-control disorders; and ma jor neurocognitive disorder. Major depres-
sive disorder may occur througho ut the range of severity of intellectual disability. Self-
injurious behavior requires pr ompt diagnostic attention and may warrant a separate di-
agnosis of stereotypic movement  disorder. Individuals with intellectual disability, partic-
ularly those with more severe intellectual disability, may also exhibit aggression and
disruptive behaviors, including harm of others or property destruction.
Relationship to Ot her Classifications
ICD-11 (in development at the time of  this publication) uses the term intellectual develop-
mental disorders  to indicate that these are disorders that involve impaired brain functioning
early in life. These disorders are described in  ICD-11 as a metasyndrome occurring in the
developmental period analogous to dementia or neurocognitive disorder in later life.


developmental period analogous to dementia or neurocognitive disorder in later life.
There are four subtypes in ICD-11: mild, moderate, severe, and profound.
The American Association on Intellectual and Developmental Disabilities (AAIDD)
also uses the term intellectual disability  with a similar meaning to the term as used in this


Global Developmental Delay 41
manual. The AAIDD’s classification is multidimensional rather than categorical and is
based on the disability construc t. Rather than listing specifie rs as is done in DSM-5, the
AAIDD emphasizes a profile of supports based on severity.
Global Developmental Delay
315.8 (F88)
This diagnosis is reserved for individuals under  the age of 5 years when the clinical severity
level cannot be reliably assessed during early childhood. This category is diagnosed when
an individual fails to meet expected developmental  milestones in several areas of intellec-
tual functioning, and applies to individuals  who are unable to undergo systematic assess-
ments of intellectual functioning, including children who are too young to participate in
standardized testing. This category requires reassessment after a period of time.
Unspecified Intellectual Disability
(Intellectual Developmental Disorder)
319 (F79)
This category is rese rved for individuals over the age of 5 years when assessment of the
degree of intellectual disabi lity (intellectual developmental disorder) by means of locally
available procedures is rendered difficult or impossible because of associated sensory or
physical impairments, as in blindness or prel ingual deafness; locomotor disability; or pres-
ence of severe problem behaviors or co-occurring mental disorder. This category should
only be used in exceptional circumstances and requires reassessment after a period of time.
Communication Disorders
Disorders of communication include deficits  in language, speech, and communication.
Speech  is the expressive production of sounds and includes an indivi dual’s articulation,
fluency, voice, and resonance quality. Language  includes the form, fu nction, and use of a
conventional system of symbol s (i.e., spoken words, sign language, written words, pic-


tures) in a rule -governed manner for communication. Communication  includes any verbal
or nonverbal behavior (whether intentional or unintentional) that influences the behavior,
ideas, or attitudes of another individual. Assessments of speech, language and communi-
cation abilities must take into account the individual's cultural and language context,
particularly for individuals growing up in bilingual environments. The standardized mea-
sures of language development and of nonverba l intellectual capacity must be relevant for
the cultural and linguistic group (i.e., tests developed and standardized for one group may
not provide appropriate norms for a different group). The diagnostic category of commu-
nication disorders includes the following: language disorder, speech sound disorder,
childhood-onset fluency disord er (stuttering), social (pra gmatic) communication disor-
der, and other specified and unspecified communica tion disorders.


42 Neurodevelopmental Disorders
Language Disorder
Diagnostic Criteria 315.32 (F80.2)
A. Persistent difficulties in the acquisition and use of language across modalities (i.e.,
spoken, written, sign language, or other) due to deficits in comprehension or produc-
tion that include the following:
1. Reduced vocabulary (word knowledge and use).
2. Limited sentence structure (ability to put words and word endings together to form
sentences based on the rules of grammar and morphology).
3. Impairments in discourse (ability to use vocabulary and connect sentences to ex-
plain or describe a topic or series of events or have a conversation).
B. Language abilities are substantially and quantifiably below those expected for age, re-
sulting in functional limitations in effective communication, social participation, aca-
demic achievement, or occupational performance, individually or in any combination.
C. Onset of symptoms is in the early developmental period.
D. The difficulties are not attributable to hearing or other sensory impairment, motor dys-
function, or another medical or neurological condition and are not better explained by in-
tellectual disability (intellectual developmental disorder) or global developmental delay.
Diagnostic Features
The core diagnostic features of language disorder are difficulties in the acquisition and use
of language due to deficits in the comprehe nsion or production of vocabulary, sentence
structure, and discourse. The language defi cits are evident in spoken communication,
written communication, or sign language. La nguage learning and use is dependent on
both receptive and expressive skills. Expressive ability refers to the production of vocal, ges-
tural, or verbal signals, while receptive ability  refers to the process of receiving and com-
prehending language messages. Language skills  need to be assessed in both expressive


prehending language messages. Language skills  need to be assessed in both expressive
and receptive modalities as these may differ in severity. For example, an individual’s ex-
pressive language may be seve rely impaired, while his recept ive language is hardly im-
paired at all.
Language disorder usually affects vocabulary and grammar, and these effects then
limit the capacity for discourse. The child’s fi rst words and phrases are likely to be delayed
in onset; vocabulary size is smaller and less varied than expected; and sentences are
shorter and less complex with grammatical errors , especially in past tense. Deficits in com-
prehension of language are fr equently underestimated, as children may be good at using
context to infer meaning. There may be word-finding problems, impoverished verbal def-
initions, or poor understand ing of synonyms, multiple meanings, or word play appro-
priate for age and culture. Problems with  remembering new words and sentences are
manifested by difficulties following instructions of increasing length, difficulties rehears-
ing strings of verbal information (e.g., remembering a phone number or a shopping list),
and difficulties remembering novel sound se quences, a skill that may be important for
learning new words. Difficulties with discour se are shown by a reduced ability to provide
adequate information abou t the key events and to narrate a coherent story.
The language difficulty is manifest by abilities substantially and quantifiably below
that expected for age and significantly inte rfering with academic achievement, occupa-
tional performance, effective communication, or  socialization (Criterion B). A diagnosis of
language disorder is made based on the synthesis of the individual’s history, direct clinical
observation in different contexts (i.e., home, school, or work), and scores from standard-
ized tests of language ability that can be  used to guide estimates of severity.


Language Disorder 43
Associated Features Supporting Diagnosis
A positive family history of language disorders is often present. Individuals, even chil-
dren, can be adept at accommodating to their limited language. They may appear to be shy
or reticent to talk. Affected individuals may prefer to communicate only with family mem-
bers or other familiar individuals. Although these social indicators are not diagnostic of a
language disorder, if they are notable and pers istent, they warrant referral for a full lan-
guage assessment. Language d isorder, particularly expressiv e deficits, may co-occur with
speech sound disorder.
Development and Course
Language acquisition is marked by changes from  onset in toddlerhood to the adult level of
competency that appears during adolescence.  Changes appear across the dimensions of
language (sounds, words, grammar, narrati ves/expository texts, and conversational
skills) in age-graded increments and synchron ies. Language disorder emerges during the
early developmental period; however, there is considerable variation in early vocabulary
acquisition and early word combinations, an d individual differenc es are not, as single
indicators, highly predictive of later outcomes. By age 4 years, individual differences in
language ability are more stable, with bette r measurement accuracy, and are highly pre-
dictive of later outcomes. Language disorder diagnosed from 4 years of age is likely to be
stable over time and typically persists into adulthood, although the particular profile of
language strengths and deficits is likely to change over the course of development.
Risk and Prognostic Factors
Children with receptive language impairment s have a poorer prognosis than those with
predominantly expressive impairments. They are more resistant to treatment, and diffi-
culties with reading comprehe nsion are frequently seen.
Genetic and physiological. Language disorders are highly heritable, and family mem-


Genetic and physiological. Language disorders are highly heritable, and family mem-
bers are more likely to have a history of language impairment.
Differential Diagnosis
Normal variations in language. Language disorder needs to be distinguished from nor-
mal developmental variations, and this distinctio n may be difficult to make before 4 years
of age. Regional, social, or cultural/ethnic va riations of language (e.g., dialects) must be
considered when an individual is being assessed for language impairment.
Hearing or other sensory impairment. Hearing impairment needs to be excluded as the
primary cause of language difficulties. Langua ge deficits may be associated with a hearing
impairment, other sensory deficit, or a speech-motor deficit. When language deficits are in
excess of those usually associ ated with these problems, a di agnosis of language disorder
may be made.
Intellectual disability (intell ectual developmental disorder). Language delay is often the
presenting feature of intellect ual disability, and the definitive diagnosis may not be made
until the child is able to complete standard ized assessments. A separate diagnosis is not
given unless the language deficits are clearl y in excess of the intellectual limitations.
Neurological disorders. Language disorder can be acquired in association with neuro-
logical disorders, including epilepsy (e.g., ac quired aphasia or Landau-Kleffner syndrome).
Language regression. Loss of speech and language in a child younger than 3 years may
be a sign of autism spectrum disorder (with developmental regression) or a specific neuro-
logical condition, such as Landau-Kleffner syndrome. Among children older than 3 years,
language loss may be a symptom of seizures, and a diagnostic assessment is necessary to
exclude the presence of epilepsy (e.g., routine and sleep electroencephalogram).


44 Neurodevelopmental Disorders
Comorbidity
Language disorder is strongly associated with other neurodevelopmental disorders in
terms of specific learning d isorder (literacy and numeracy),  attention-deficit/hyperactiv-
ity disorder, autism spectrum disorder, and developmental coordination disorder. It is
also associated with social (pragmatic) commu nication disorder. A positive family history
of speech or language disorders is often present.
Speech Sound Disorder
Diagnostic Criteria 315.39 (F80.0)
A. Persistent difficulty with speech sound production that interferes with speech intelligi-
bility or prevents verbal communication of messages.
B. The disturbance causes limitations in effect ive communication that interfere with social
participation, academic achievement, or occupational performance, individually or in
any combination.
C. Onset of symptoms is in the early developmental period.
D. The difficulties are not attributable to congenital or acquired conditions, such as cere-
bral palsy, cleft palate, deafness or hearing loss, traumatic brain injury, or other medi-
cal or neurological conditions.
Diagnostic Features
Speech sound production descri bes the clear articulation of  the phonemes (i.e., individual
sounds) that in combination make up spoken words. Speech sound production requires both
the phonological knowledge of speech sounds and the ability to coordinate the movements of
the articulators (i.e., the jaw, tongue, and lips ,) with breathing and vocalizing for speech. Chil-
dren with speech production difficulties may experience difficulty with phonological knowl-
edge of speech sounds or the ability to coordi nate movements for speech in varying degrees.
Speech sound disorder is thus heterogeneous in its underlying mechanisms and includes pho-
nological disorder and articulation disorder . A speech sound disorder is diagnosed when


nological disorder and articulation disorder . A speech sound disorder is diagnosed when
speech sound production is not what would be expected based on the child’s age and devel-
opmental stage and when the deficits are not the result of a physical, st ructural, neurological,
or hearing impairment. Among typically develo ping children at age 4 years, overall speech
should be intelligible, whereas at age 2 years, only 50% may be understandable.
Associated Features Supporting Diagnosis
Language disorder, particularly expressive de ficits, may be found to co-occur with speech
sound disorder. A positive family history of speech or language  disorders is often present.
If the ability to rapidly coordinate the articu lators is a particular aspect of difficulty,
there may be a history of delay or incoordinati on in acquiring skills that also utilize the
articulators and related facial musculature; among others, these sk ills include chewing,
maintaining mouth closure, and blowing the no se. Other areas of motor coordination may
be impaired as in developm ental coordination disorder. Verbal dyspraxia  is a term also
used for speech prod uction problems.
Speech may be differentially impaired in ce rtain genetic conditions (e.g., Down syn-
drome, 22q deletion, FoxP2  gene mutation). If present, these should also be coded.
Development and Course
Learning to produce speech sounds clearly and accurately and learning to produce con-
nected speech fluently are developmental skills. Articulation of speech sounds follows a


Childhood-Onset Fluency Disorder (Stuttering) 45
developmental pattern, which is reflected in the age norms of standardized tests. It is not
unusual for typically developing children to  use developmental processes for shortening
words and syllables as they are learning to talk, but their progression in mastering speech
sound production should result in mostly in telligible speech by age 3 years. Children with
speech sound disorder continue to use immature phonological simplification processes
past the age when most children can produce words clearly.
Most speech sounds should be produced cl early and most words should be pronounced
accurately according to age an d community norms by age 7 years. The most frequently mis-
articulated sounds also tend to be learned later, leading them to be called the “late eight” ( l, r,
s, z, th, ch, dzh, and zh). Misarticulation of an y of these sounds by it self could be considered
within normal limits up to age 8 years. When multiple sounds are involved, it may be appro-
priate to target some of those sounds as part of  a plan to improve intelligibility prior to the age
at which almost all children can produce them a ccurately. Lisping (i.e., misarticulating sibi-
lants) is particularly common and may involve fr ontal or lateral patterns of airstream direc-
tion. It may be associated with an ab normal tongue-thrust swallowing pattern.
Most children with speech sound disorder re spond well to treatment, and speech dif-
ficulties improve over time, and thus the diso rder may not be lifelong. However, when a
language disorder is also present, the spee ch disorder has a poorer prognosis and may be
associated with specific learning disorders.
Differential Diagnosis


associated with specific learning disorders.
Differential Diagnosis
Normal variations in speech. Regional, social, or cultural/ethnic variations of speech
should be considered before making the diagnosis.
Hearing or other sensory impairment. Hearing impairment or deafness may result in
abnormalities of speech. Defici ts of speech sound production may be associated with a
hearing impairment, other sensory deficit, or a speech-mo tor deficit. When speech deficits
are in excess of those usually associated with these problems, a diagnosis of speech sound
disorder may be made.
Structural deficits. Speech impairment may be due to stru ctural deficits (e.g., cleft palate).
Dysarthria. Speech impairment may be attributable to a motor disorder, such as cerebral
palsy. Neurological signs, as well as distinct ive features of voice, differentiate dysarthria
from speech sound disorder, although in young children (under 3 years) differentiation
may be difficult, particularly  when there is no or minima l general body motor involve-
ment (as in, e.g., Worster-Drought syndrome).
Selective mutism. Limited use of speech may be a sign  of selective mutism, an anxiety
disorder that is characterized by a lack of sp eech in one or more contexts or settings. Se-
lective mutism may develop in children with a speech disorder because of embarassment
about their impairments, but many children with selective mutism exhibit normal speech
in “safe” settings, such as at home or with close friends.
Childhood-Onset Fluency Disorder (Stuttering)
Diagnostic Criteria 315.35 (F80.81)
A. Disturbances in the normal fluency and time patterning of speech that are inappropri-
ate for the individual’s age and language skills, persist over time, and are characterized


ate for the individual’s age and language skills, persist over time, and are characterized
by frequent and marked occurrences of one (or more) of the following:
1. Sound and syllable repetitions.
2. Sound prolongations of consonants as well as vowels.


46 Neurodevelopmental Disorders
3. Broken words (e.g., pauses within a word).
4. Audible or silent blocking (filled or unfilled pauses in speech).
5. Circumlocutions (word substitutions to avoid problematic words).
6. Words produced with an excess of physical tension.
7. Monosyllabic whole-word repetitions (e.g., “I-I-I-I see him”).
B. The disturbance causes anxiety about speaking or limitations in effective communica-
tion, social participation, or academic or occupational performance, individually or in
any combination.
C. The onset of symptoms is in the early developmental period. ( Note:  Later-onset cases
are diagnosed as 307.0 [F98.5] adult-onset fluency disorder.)
D. The disturbance is not attributable to a s peech-motor or sensory deficit, dysfluency as-
sociated with neurological insult (e.g., stroke, tumor, trauma), or another medical con-
dition and is not better explained by another mental disorder.
Diagnostic Features
The essential feature of childho od-onset fluency disorder (stu ttering) is a disturbance in
the normal fluency and time patterning of spee ch that is inappropriate for the individual’s
age. This disturbance is characterized by freq uent repetitions or prolongations of sounds
or syllables and by other types of speech dysfluencies, including broken words (e.g.,
pauses within a word), audible or silent blocki ng (i.e., filled or unfilled pauses in speech),
circumlocutions (i.e., word su bstitutions to avoid proble matic words), words produced
with an excess of physical tension, and mono syllabic whole-word repetitions (e.g., “I-I-I-I
see him”). The disturbance in fluency interferes with academic or occupational achieve-


see him”). The disturbance in fluency interferes with academic or occupational achieve-
ment or with social communication. The extent  of the disturbance varies from situation to
situation and often is more severe when there is special pressure to communicate (e.g., giv-
ing a report at school, interviewing for a job) . Dysfluency is often absent during oral read-
ing, singing, or talking to inanimate objects or to pets.
Associated Features Supporting Diagnosis
Fearful anticipation of the problem may develop. The speaker may attempt to avoid dys-
fluencies by linguistic mechanisms (e.g., al tering the rate of sp eech, avoiding certain
words or sounds) or by avoiding certain speec h situations, such as telephoning or public
speaking. In addition to being features of the condition, stress and anxiety have been
shown to exacerbate dysfluency.
Childhood-onset fluency diso rder may also be accompanied by motor movements
(e.g., eye blinks, tics, tremors of the lips or face, jerking of the head, breathing movements,
fist clenching). Children with fluency disorder  show a range of language abilities, and the
relationship between fluency disorder  and language abilities is unclear.
Development and Course
Childhood-onset fluency disord er, or developmental stutteri ng, occurs by age 6 for 80%–
90% of affected individuals, with age at onset ranging from 2 to 7 years. The onset can be
insidious or more sudden. Typically, dysfluencies  start gradually, with repetition of initial
consonants, first words of a phrase, or long words. The child may not be aware of dysflu-
encies. As the disorder progresses, the dysfluencies become more frequent and interfering,


encies. As the disorder progresses, the dysfluencies become more frequent and interfering,
occurring on the most meaningful words or phr ases in the utterance. As the child becomes
aware of the speech difficulty, he or she may develop mechanisms for avoiding the dys-
fluencies and emotional responses, including avoidance of public speaking and use of
short and simple utterances. Longitudinal research shows that 65%–85% of children re-


Social (Pragmatic) Communication Disorder 47
cover from the dysfluency, with severity of fl uency disorder at age 8 years predicting re-
covery or persistence into adolescence and beyond.
Risk and Prognostic Factors
Genetic and physiological. The risk of stuttering among first-degree biological rela-
tives of individuals wi th childhood-onset fluency disorder  is more than three times the
risk in the general population.
Functional Consequences of
Childhood-Onset Fluency Disorder (Stuttering)
In addition to being features of the condit ion, stress and anxiety can exacerbate dysflu-
ency. Impairment of social function ing may result from this anxiety.
Differential Diagnosis
Sensory deficits. Dysfluencies of speech may be associated with a hearing impairment
or other sensory deficit or a sp eech-motor deficit. When the speech dysfluencies are in ex-
cess of those usually associated with these problems, a diagnosis of childhood-onset flu-
ency disorder may be made.
Normal speech dysfluencies. The disorder must be distinguished from normal dysflu-
encies that occur frequently in young children, which include whole-word or phrase rep-
etitions (e.g., “I want, I want ice cream”), incomplete phrases, in terjections, unfilled
pauses, and parenthetical remarks. If these difficulties increase in frequency or complexity
as the child grows older, a diagnosis of child hood-onset fluency diso rder is appropriate.
Medication side effects. Stuttering may occur as a side effect of medication and may be
detected by a temporal relationship with exposure to the medication.
Adult-onset dysfluencies. If onset of dysfluencies is during  or after adolescence, it is an


“adult-onset dysfluency” rather than a neurodevelopmental disorder . Adult-onset dysflu-
encies are associated with specific neurologic al insults and a variety of medical conditions
and mental disorders and may be specified with them, but they are not a DSM-5 diagnosis.
Tourette’s disorder. Vocal tics and repetitive vocalizations of  Tourette’s disorder
should be distinguishable from  the repetitive sounds of childhood-onset fluency disorder
by their nature and timing.
Social (Pragmatic) Communication Disorder
Diagnostic Criteria 315.39 (F80.89)
A. Persistent difficulties in the social use of verbal and nonverbal communication as man-
ifested by all of the following:
1. Deficits in using communication for social purposes, such as greeting and sharing
information, in a manner that is appropriate for the social context.
2. Impairment of the ability to change communication to match context or the needs of
the listener, such as speaking differently in a classroom than on a playground, talk-
ing differently to a child than to an adul t, and avoiding use of overly formal language.
3. Difficulties following rules for conversation and storytelling, such as taking turns in
conversation, rephrasing when misunderstoo d, and knowing how to use verbal and
nonverbal signals to regulate interaction.


48 Neurodevelopmental Disorders
4. Difficulties understanding what is not explicitly stated (e.g., making inferences) and
nonliteral or ambiguous meanings of language (e.g., idioms, humor, metaphors,
multiple meanings that depend on the context for interpretation).
B. The deficits result in functional limitations in effective communication, social participa-
tion, social relationships, academic achievement, or occupational performance, indi-
vidually or in combination.
C. The onset of the symptoms is in the ear ly developmental period (but deficits may not
become fully manifest until social communication demands exceed limited capacities).
D. The symptoms are not attributable to another medical or neurological condition or to low
abilities in the domains of word structure and grammar, and are not better explained by
autism spectrum disorder, intellectual dis ability (intellectual developmental disorder),
global developmental delay, or another mental disorder.
Diagnostic Features
Social (pragmatic) communication  disorder is characterized by a primary difficulty with
pragmatics, or the social use of language an d communication, as manifested by deficits in
understanding and following social rules of verbal and nonverbal communication in nat-
uralistic contexts, changing language accordin g to the needs of the listener or situation,
and following rules for conversations and stor ytelling. The deficits in social communica-
tion result in functional limitations in effective communicatio n, social participation, devel-
opment of social relationships, academic ac hievement, or occupational performance. The
deficits are not better explaine d by low abilities in the domains of structural language or
cognitive ability.
Associated Features Supporting Diagnosis
The most common associated feat ure of social (pragmatic) co mmunication disorder is lan-
guage impairment, which is characterized by a history of delay in reaching language mile-


guage impairment, which is characterized by a history of delay in reaching language mile-
stones, and historical, if not current, structur al language problems (see “Language Disorder”
earlier in this chapter). Individuals with social  communication deficits may avoid social inter-
actions. Attention-deficit/hype ractivity disorder (ADHD), beha vioral problems, and specific
learning disorders are also more common among affected individuals.
Development and Course
Because social (pragmatic) co mmunication depends on adeq uate developmental progress
in speech and language, diagnosis of social (pragmatic) communication disorder is rare
among children younger than 4 years. By ag e 4 or 5 years, most  children should possess
adequate speech and language abilities to permit identification of specific deficits in social
communication. Milder forms of  the disorder may not become apparent until early ado-
lescence, when language and social interactions become more complex.
The outcome of social (pragmatic) communicat ion disorder is variable, with some chil-
dren improving substantially over time and othe rs continuing to have difficulties persist-
ing into adulthood. Even am ong those who have significant improvements, the early
deficits in pragmatics may cause lasting impa irments in social relationships and behavior
and also in acquisition of other rela ted skills, such as written expression.
Risk and Prognostic Factors
Genetic and physiological. A family history of autism spectrum disorder, communica-
tion disorders, or specific learning disorder appears to increase the risk for social (prag-
matic) communication disorder.


Unspecified Communication Disorder 49
Differential Diagnosis
Autism spectrum disorder. Autism spectrum disorder is  the primary diagnostic con-
sideration for individuals presenting with social communication de ficits. The two disor-
ders can be differentiated by the presence in  autism spectrum disorder of restricted/
repetitive patterns of behavior , interests, or activities and their absence in social (prag-
matic) communication disorder. Individuals wi th autism spectrum disorder may only dis-
play the restricted/repetitive patterns of behavi or, interests, and activities during the early
developmental period, so a co mprehensive history should be  obtained. Current absence of
symptoms would not preclude a diagnosis of autism spectrum  disorder, if the restricted
interests and repetitive behaviors were present in the past. A diagnosis of social (prag-
matic) communication disorder should be considered only if the developmental history
fails to reveal any evidence of restricted/repetitive patterns of behavior, interests, or ac-
tivities.
Attention-deficit/hyperactivity disorder. Primary deficits of AD HD may cause impair-
ments in social communication and functional limitations of effectiv e communication, so-
cial participation, or academic achievement.
Social anxiety disorder (social phobia). The symptoms of social communication disor-
der overlap with those of social anxiety diso rder. The differentiating feature is the timing
of the onset of symptoms. In social (pragm atic) communication di sorder, the individual
has never had effective social communication; in social anxiety disorder, the social com-
munication skills developed appr opriately but are not utilized because of anxiety, fear, or
distress about social interactions.
Intellectual disability (intellectual developm ental disorder) and global developmental
delay. Social communication skills may be deficient among individuals with global de-


delay. Social communication skills may be deficient among individuals with global de-
velopmental delay or in tellectual disability, but a separa te diagnosis is not given unless
the social communication deficits are clearl y in excess of the intellectual limitations.
Unspecified Communication Disorder
307.9 (F80.9)
This category applies to presentations in which symptoms characteristic of communication
disorder that cause clinically significant distress or impairment in social, occupational, or
other important areas of func tioning predominate but do not meet the full criteria for com-
munication disorder or for any of the disorders in the neurodevelopmental disorders diag-
nostic class. The unspecified communication disorder category is used in situations in
which the clinician chooses not to specify the reason that the criteria are not met for com-
munication disorder or for a specific neurodevelopmental disorder, and includes presen-
tations in which there is insufficient information to make a more specific diagnosis.


50 Neurodevelopmental Disorders
Autism Spectrum Disorder
Autism Spectrum Disorder
Diagnostic Criteria 299.00 (F84.0)
A. Persistent deficits in social communication and social interaction across multiple con-
texts, as manifested by the following, currently or by history (examples are illustrative,
not exhaustive; see text):
1. Deficits in social-emotional reciprocit y, ranging, for example, from abnormal social
approach and failure of normal back-and-fort h conversation; to reduced sharing of
interests, emotions, or affect; to failure to initiate or respond to social interactions.
2. Deficits in nonverbal communicative behavi ors used for social interaction, ranging,
for example, from poorly integrated ver bal and nonverbal communication; to abnor-
malities in eye contact and body language or deficits in understanding and use of
gestures; to a total lack of facial expressions and nonverbal communication.
3. Deficits in developing, maintaining, and understanding relationships, ranging, for ex-
ample, from difficulties adjusting behavior to suit various social contexts; to difficulties
in sharing imaginative play or in making friends; to absence of interest in peers.
Specify current severity:
Severity is based on social communicat ion impairments and restricted, re-
petitive patterns of behavior  (seeTable 2).
B. Restricted, repetitive patterns of behavior, interests, or activities, as manifested by at
least two of the following, currently or by history (examples are illustrative, not exhaus-
tive; see text):
1. Stereotyped or repetitive motor movements, use of objects, or speech (e.g., simple
motor stereotypies, lining up toys or flipping objects, echolalia, idiosyncratic
phrases).


phrases).
2. Insistence on sameness, inflexible adherence to routines, or ritualized patterns of
verbal or nonverbal behavior (e.g., extreme distress at small changes, difficulties
with transitions, rigid thinking patterns, greeting rituals, need to take same route or
eat same food every day).
3. Highly restricted, fixated interests that are abnormal in intensity or focus (e.g.,
strong attachment to or preoccupation with unusual objects, excessively circum-
scribed or perseverative interests).
4. Hyper- or hyporeactivity to sensory input or unusual interest in sensory aspects of
the environment (e.g., apparent indifference to pain/temperature, adverse re-
sponse to specific sounds or textures, excessive smelling or touching of objects,
visual fascination with lights or movement).
Specify current severity:
Severity is based on social communicat ion impairments and restricted, re-
petitive patterns of behavior  (see Table 2).
C. Symptoms must be present in the early developmental period (but may not become
fully manifest until social demands exceed limited capacities, or may be masked by
learned strategies in later life).
D. Symptoms cause clinically significant impai rment in social, occupat ional, or other im-
portant areas of current functioning.


Autism Spectrum Disorder 51
E. These disturbances are not better explained by  intellectual disability (intellectual devel-
opmental disorder) or global developmental delay. Intellectual disability and autism
spectrum disorder frequently co-occur; to make comorbid diagnoses of autism spec-
trum disorder and intellectual disability, social communication should be below that ex-
pected for general developmental level.
Note:  Individuals with a well-established DSM-IV diagnosis of autistic disorder, Asperger’s
disorder, or pervasive developmental disorder not otherwise specified should be given the
diagnosis of autism spectrum disorder. Individuals who have marked deficits in social
communication, but whose symptoms do not ot herwise meet criteria for autism spectrum
disorder, should be evaluated for social (pragmatic) communication disorder.
Specify if:
With or without accompanying intellectual impairment
With or without accompan ying language impairment
Associated with a known medical or gene tic condition or en vironmental factor
(Coding note:  Use additional code to identify the associated medical or genetic condition.)
Associated with another neurodevelopmen tal, mental, or behavioral disorder
(Coding note:  Use additional code[s] to identify the associated neurodevelopmental,
mental, or behavioral disorder[s].)
With catatonia  (refer to the criteria for catatonia associated with another mental dis-
order, pp. 119–120, for definition) ( Coding note:  Use additional code 293.89 [F06.1]
catatonia associated with autism spectrum disorder to indicate the presence of the co-
morbid catatonia.)
Recording Procedures
For autism spectrum disorder th at is associated with a known medical or genetic condition
or environmental factor, or with another ne urodevelopmental, mental , or behavioral dis-
order, record autism spectrum disorder associated with (name of condition, disorder, or


order, record autism spectrum disorder associated with (name of condition, disorder, or
factor) (e.g., autism spectrum disorder associated with Rett syndrome). Severity should be
recorded as level of support needed for ea ch of the two psychopa thological domains in
Table 2 (e.g., “requiring very substantial support for deficits  in social communication and
requiring substantial support fo r restricted, repetitive behaviors”). Specification of “with
accompanying intellectual impairment” or “without accompanying intellectual impair-
ment” should be recorded next. Language im pairment specification should be recorded
thereafter. If there is accompan ying language impairment, the current level of verbal func-
tioning should be recorded (e.g., “with accompanying language impairment—no intelligi-
ble speech” or “with accompanying language impairment—phrase speech”). If catatonia is
present, record separately “catatonia asso ciated with autism spectrum disorder.”
Specifiers
The severity specifiers (see Table 2) may be used to describe succinctly the current symp-
tomatology (which might fall below level 1), with  the recognition that severity may vary by
context and fluctuate over time. Severity of social communication difficulties and re-
stricted, repetitive behaviors sh ould be separately rated. The descriptive severity categories
should not be used to determine eligibility fo r and provision of services; these can only be
developed at an individual level and through di scussion of personal priorities and targets.
Regarding the specifier “with or without ac companying intellectual impairment,” un-
derstanding the (often uneven) intellectual prof ile of a child or adult with autism spectrum
disorder is necessary for interpre ting diagnostic features. Separate estimates of verbal and
nonverbal skill are necessary (e.g., using untimed nonverbal tests to assess potential
strengths in individuals with limited language).


52 Neurodevelopmental DisordersTABLE 2 Severity levels for autism spectrum disorder
Severity level Social communication Restricted, repetitive behaviors
Level 3
“Requiring very substantial support”Severe deficits in verbal and nonverbal social com-
munication skills cause severe impairments in func-
tioning, very limited initiation of social
interactions, and minimal response to social over-
tures from others. For example, a person with few
words of intelligible speech who rarely initiates
interaction and, when he or she does, makes
unusual approaches to meet needs only and
responds to only very direct social approaches.Inflexibility of behavior, extreme difficulty coping
with change, or other restricted/repetitive behav-
iors markedly interfere with functioning in all
spheres. Great distress/difficulty changing focus
or action.
Level 2
“Requiring substantial support”Marked deficits in verbal and nonverbal social com-
munication skills; social  impairments apparent
even with supports in place; limited initiation of
social interactions; an d reduced or abnormal
responses to social overtures from others. For
example, a person who sp eaks simple sentences,
whose interaction is limited to narrow special inter-
ests, and who has markedly odd nonverbal com-
munication.Inflexibility of behavior , difficulty coping with
change, or other restricted/repetitive behaviors
appear frequently enough to be obvious to the
casual observer and inte rfere with functioning
in a variety of contexts. Distress and/or difficulty
changing focus or action.
Level 1
“Requiring support”Without supports in place, deficits in social communi-
cation cause noticeable impairments.
Difficulty initiating social interactions, and clear
examples of atypical or unsuccessful responses to


Difficulty initiating social interactions, and clear
examples of atypical or unsuccessful responses to
social overtures of others. May appear to have
decreased interest in social interactions. For example,
a person who is able to speak in full sentences and
engages in communication but whose to-and-fro con-
versation with others fails, and whose attempts to
make friends are odd and typically unsuccessful.Inflexibility of behavior causes significant interfer-
ence with functioning in one or more contexts. Dif-
ficulty switching between activities. Problems of
organization and planning hamper independence.


Autism Spectrum Disorder 53
To use the specifier “with or without acco mpanying language impairment,” the cur-
rent level of verbal functioning should be ass essed and described. Ex amples of the specific
descriptions for “with accompanying language impairment” might include no intelligible
speech (nonverbal), single words only, or phrase speech. Language level in individuals
“without accompanying language impairment” might be further described by speaks in
full sentences or has fluent speech. Since receptive language may lag behind expressive
language development in autism spectrum disorder, receptive and expressive language
skills should be considered separately.
The specifier “associated with a known medica l or genetic condition or environmental fac-
tor” should be used when the individual has a known genetic disorder (e.g., Rett syndrome,
Fragile X syndrome, Down syndrome), a medical disorder (e.g. epilepsy), or a history of envi-
ronmental exposure (e.g., valproate, fetal alcohol syndrome, very low birth weight).
Additional neurodevelopmental, mental or be havioral conditions should also be noted
(e.g., attention-deficit/hypera ctivity disorder; developmenta l coordination disorder; dis-
ruptive behavior, impulse-control, or conduct disorders; anxiety, depressive, or bipolar
disorders; tics or Tourette’s disorder; self-inj ury; feeding, eliminatio n, or sleep disorders).
Diagnostic Features
The essential features of autism spectrum diso rder are persistent impairment in reciprocal
social communication and social interaction (Criterion A), and restricted, repetitive pat-
terns of behavior, interests, or activities (Criterion B). These symptoms are present from
early childhood and limit or impair everyday  functioning (Criteria C and D). The stage at
which functional impairment becomes obvious will vary according to characteristics of


which functional impairment becomes obvious will vary according to characteristics of
the individual and his or her environment. Co re diagnostic features are evident in the
developmental period, but intervention, co mpensation, and current supports may mask
difficulties in at least some contexts. Manifestations of the disorder also vary greatly de-
pending on the severity of the autistic condit ion, developmental level,  and chronological age;
hence, the term spectrum. Autism spectrum disorder enco mpasses disorders previously re-
ferred to as early infantile  autism, childhood autism, Ka nner’s autism, high-functioning
autism, atypical autism, pervasive developmen tal disorder not otherw ise specified, child-
hood disintegrative disorder , and Asperger’s disorder.
The impairments in communicat ion and social interaction specified in Criterion A are
pervasive and sustained. Diagnoses are most  valid and reliable when based on multiple
sources of information, including clinician’s observations, caregiver history, and, when
possible, self-report. Verbal and nonverbal deficits in social communication have varying
manifestations, depending on the individual’s age, intellectual level,  and language ability,
as well as other factors such as treatment history and current support. Many individuals
have language deficits, ranging from complete lack of speech through language delays,
poor comprehension of speech, echoed speech, or stilted  and overly literal language. Even
when formal language skills (e.g ., vocabulary, grammar) are intact, the use of language for
reciprocal social communication is im paired in autism spectrum disorder.
Deficits in social-emotional reciprocity (i.e.,  the ability to engage with others and share
thoughts and feelings) are cl early evident in young children with the disorder, who may
show little or no initiation of social interaction and no sharing of emotions, along with re-


show little or no initiation of social interaction and no sharing of emotions, along with re-
duced or absent imitation of others’ behavior . What language exists is often one-sided,
lacking in social reciprocity, and used to re quest or label rather th an to comment, share
feelings, or converse. In adults without inte llectual disabilities or language delays, deficits


lacking in social reciprocity, and used to re quest or label rather th an to comment, share
feelings, or converse. In adults without inte llectual disabilities or language delays, deficits
in social-emotional reciprocity may be most apparent in difficulties processing and re-
sponding to complex social cues (e.g., when  and how to join a conversation, what not to
say). Adults who have developed compensation strategies for some social challenges still
struggle in novel or un supported situations and suffer fr om the effort and anxiety of con-
sciously calculating what is social ly intuitive for most individuals.


54 Neurodevelopmental Disorders
Deficits in nonverbal communicative behavi ors used for social interaction are mani-
fested by absent, reduced, or atypical use of  eye contact (relative to cultural norms), ges-
tures, facial expressions, body  orientation, or speech intona tion. An early feature of autism
spectrum disorder is impaired joint attention as manifested by  a lack of pointing, showing,
or bringing objects to share interest with others, or failure to follow someone’s pointing or
eye gaze. Individuals may learn a few functional  gestures, but their re pertoire is smaller
than that of others, and they often fail to use expressive gestures spontaneously in com-
munication. Among adults with fluent language, the difficulty in coordinating nonverbal
communication with speech may give the impr ession of odd, wooden, or exaggerated
“body language” during interactions. Impairme nt may be relatively subtle within indi-
vidual modes (e.g., someone may have relati vely good eye contact when speaking) but
noticeable in poor integration of eye contact, gesture, body posture, prosody, and facial ex-
pression for social communication.
Deficits in developing, maintaining, an d understanding relationships should be
judged against norms for age, gender, and culture. There may be absent, reduced, or atyp-
ical social interest, manifested by rejectio n of others, passivity, or inappropriate ap-
proaches that seem aggressive or disruptive . These difficulties are particularly evident in
young children, in whom there is often a lack of shared social play and imagination (e.g.,
age-appropriate flexible pretend play) and, late r, insistence on playing by very fixed rules.
Older individuals may struggle to understand what behavior is considered appropriate in


Older individuals may struggle to understand what behavior is considered appropriate in
one situation but not another (e.g., casual beha vior during a job interview), or the different
ways that language may be used to communic ate (e.g., irony, white lies). There may be an
apparent preference for solitary activities or  for interacting with much younger or older
people. Frequently, there is a de sire to establish friendships wi thout a complete or realistic
idea of what friendship entails (e.g., one-sid ed friendships or friendships based solely on
shared special interests). Relationships with siblings, co-workers, and caregivers are also
important to consider (i n terms of reciprocity).
Autism spectrum disorder is also defined by restricted, repetitive patterns of behavior,
interests, or activities (as specified in Criterion B), which show a range of manifestations
according to age and ability, intervention, and current supports. Stereotyped or repetitive
behaviors include simple motor stereotypies (e.g., hand flappi ng, finger flicking), repeti-
tive use of objects (e.g., spinning coins, linin g up toys), and repetitive speech (e.g., echola-
lia, the delayed or immediate parroting of heard words; use of “you” when referring to
self; stereotyped use of words, phrases, or pr osodic patterns). Exce ssive adherence to rou-
tines and restricted patterns of behavior may be manifest in resistance to change (e.g., dis-
tress at apparently small changes, such as in packaging of a favorite food; insistence on
adherence to rules; rigidity of thinking) or ri tualized patterns of ve rbal or nonverbal be-
havior (e.g., repetitive questioning, pacing a perimeter). Highly restricted, fixated interests


havior (e.g., repetitive questioning, pacing a perimeter). Highly restricted, fixated interests
in autism spectrum disorder tend to be ab normal in intensity or  focus (e.g., a toddler
strongly attached to a pan; a child preoccupied with vacuum cleaners; an adult spending
hours writing out timetables). Some fascinations and routines may relate to apparent hy-
per- or hyporeactivity to sensory input, ma nifested through extreme responses to specific
sounds or textures, excessive smelling or touc hing of objects, fascination with lights or
spinning objects, and sometimes apparent indi fference to pain, heat, or cold. Extreme re-


sounds or textures, excessive smelling or touc hing of objects, fascination with lights or
spinning objects, and sometimes apparent indi fference to pain, heat, or cold. Extreme re-
action to or rituals involving taste, smell, te xture, or appearance of  food or excessive food
restrictions are common and ma y be a presenting feature of  autism spectrum disorder.
Many adults with autism spectrum disord er without intellectual or language disabili-
ties learn to suppress repetitive behavior in  public . Specia l interests may  be a source of
pleasure and motivation and provide avenues for education and employment later in life.
Diagnostic criteria may be met when restricted, repetitive patterns of behavior, interests,
or activities were clearly pres ent during childhood or at some time in the past, even if
symptoms are no longer present.


Autism Spectrum Disorder 55
Criterion D requires that the features must ca use clinically significant impairment in so-
cial, occupational, or other impo rtant areas of current function ing. Criterion E specifies that
the social communication defici ts, although sometime s accompanied by intellectual disabil-
ity (intellectual developmental disorder), are not in line with the individual’s developmental
level; impairments exceed difficulties expected on the basis of developmental level.
Standardized behavioral diagnostic instruments with good psychometric properties,
including caregiver interviews, questionnair es and clinician observation measures, are
available and can improve re liability of diagnosis over time and across clinicians.
Associated Features Supporting Diagnosis
Many individuals with autism spectrum disorder also have intellectual impairment and/or
language impairment (e.g., slow  to talk, language comprehension behind production). Even
those with average or high inte lligence have an uneven profil e of abilities. The gap between
intellectual and adaptive function al skills is often large. Moto r deficits are often present, in-
cluding odd gait, clumsiness, and other abnormal  motor signs (e.g., walk ing on tiptoes). Self-
injury (e.g., head banging, biting the wris t) may occur, and disr uptive/challenging behav-
iors are more common in children and adoles cents with autism spectrum disorder than
other disorders, including intellectual disabili ty. Adolescents and adults with autism spec-
trum disorder are prone to anxiety and depres sion. Some individuals develop catatonic-like
motor behavior (slowing and “f reezing” mid-action), but thes e are typically not of the mag-
nitude of a catatonic episode. However, it is possible for individuals with autism spectrum
disorder to experience a marked deterioratio n in motor symptoms an d display a full cata-


disorder to experience a marked deterioratio n in motor symptoms an d display a full cata-
tonic episode with symptoms such as mutism, posturing, grimacing and waxy flexibility.
The risk period for comorbid catatonia appears to be greate st in the adolescent years.
Prevalence
In recent years, reported frequencies for au tism spectrum disorder  across U.S. and non-
U.S. countries have approached 1% of the po pulation, with similar estimates in child and
adult samples. It remains unclear whether high er rates reflect an expansion of the diag-
nostic criteria of DSM-IV to include subthreshold cases, increased awareness, differences
in study methodology, or a true increase in  the frequency of autism spectrum disorder.
Development and Course
The age and pattern of onset also should be noted for autism spectr um disorder. Symptoms
are typically recognized during th e second year of life (12–24 months of age) but may be seen
earlier than 12 months if developmental delays  are severe, or noted later than 24 months if
symptoms are more subtle. The pattern of onset description might include information
about early developmental delays or any losses of social or language skills. In cases where
skills have been lost, parents or caregivers may give a history of a gradual or relatively
rapid deterioration in social behaviors or lang uage skills. Typically, this would occur be-
tween 12 and 24 months of age and is distinguished from the rare instances of developmen-
tal regression occurring after at least 2 years of normal development (previously described
as childhood disintegrative disorder).
The behavioral features of autism spectrum  disorder first become evident in early
childhood, with some cases presenting a lack of  interest in social interaction in the first
year of life. Some children with autism spectrum disorder experience developmental pla-


year of life. Some children with autism spectrum disorder experience developmental pla-
teaus or regression, with a gradual or relatively rapid deterioration in social behaviors or
use of language, often du ring the first 2 years of life. Such losses are rare in other disor-
ders and may be a useful “red flag” for autism spectrum disorder. Much more unusual


use of language, often du ring the first 2 years of life. Such losses are rare in other disor-
ders and may be a useful “red flag” for autism spectrum disorder. Much more unusual
and warranting more extensive medical invest igation are losses of skills beyond social
communication (e.g., loss of se lf-care, toileting, motor skills) or those occurring after the


56 Neurodevelopmental Disorders
second birthday (see also Rett syndrome in  the section “Differential Diagnosis” for this
disorder).
First symptoms of autism spectrum disorder frequently involve delayed language de-
velopment, often accompanied by lack of social interest or unusual social interactions (e.g.,
pulling individuals by the hand without any a ttempt to look at them ), odd play patterns
(e.g., carrying toys around but never pl aying with them), and unusual communication
patterns (e.g., knowing the alphabet but not responding to own name). Deafness may be
suspected but is typically ruled out. During the second year, odd and repetitive behaviors
and the absence of typical play become more apparent. Since many typically developing
young children have strong preferences and en joy repetition (e.g., eating the same foods,
watching the same vide o multiple times), dist inguishing restricted and repetitive behav-
iors that are diagnostic of autism spectrum disorder can be difficult in preschoolers. The
clinical distinction is based on the type, freq uency, and intensity of the behavior (e.g., a
child who daily lines up objects for hours an d is very distressed if any item is moved).
Autism spectrum disorder is not a degenera tive disorder, and it is typical for learning
and compensation to continue throughout life.  Symptoms are often most marked in early
childhood and early school years, with deve lopmental gains typical in later childhood in
at least some areas (e.g., increa sed interest in social interact ion). A small proportion of in-
dividuals deteriorate behaviorally during adolescence, whereas most others improve.
Only a minority of individuals with autism  spectrum disorder live and work indepen-
dently in adulthood; those who do  tend to have superior lang uage and intellectual abilities


dently in adulthood; those who do  tend to have superior lang uage and intellectual abilities
and are able to find a niche that matches thei r special interests and skills. In general, indi-
viduals with lower levels of impairment may be better able to function independently.
However, even these individuals may remain socially naive and vulnerable, have difficul-
ties organizing practical dema nds without aid, and are pron e to anxiety and depression.
Many adults report using compensation strate gies and coping mechanisms to mask their
difficulties in public but suffer from the stress  and effort of maintaining a socially accept-
able facade. Scarcely anything is known ab out old age in autism  spectrum disorder.
Some individuals come for first diagnosis in  adulthood, perhaps prompted by the diagno-
sis of autism in a child in the family or a breakdown of relations at work or home. Obtaining de-
tailed developmental history in such  cases may be difficult, and it  is important to consider self-
reported difficulties. Where clinical observat ion suggests criteria are currently met, autism
spectrum disorder may be diagno sed, provided there is no evidence of good social and com-
munication skills in childhood. For example, the re port (by parents or another relative) that the
individual had ordinary and sustained recipr ocal friendships and good nonverbal communi-
cation skills throughout childhood would rule out a diagnosis of autism spectrum disorder;
however, the absence of de velopmental information in itself should not do so.
Manifestations of the social and communication impairments and restricted/repeti-
tive behaviors that define autism spectrum d isorder are clear in th e developmental period.
In later life, intervention or compensation, as well as current supports, may mask these dif-


In later life, intervention or compensation, as well as current supports, may mask these dif-
ficulties in at least some co ntexts. However, symptoms remain sufficient to cause current
impairment in social, occupational, or  other important areas of functioning.
Risk and Prognostic Factors
The best established prognostic factors for individual outcome wi thin autism spectrum
disorder are presence or absence of associa ted intellectual disability and language impair-


The best established prognostic factors for individual outcome wi thin autism spectrum
disorder are presence or absence of associa ted intellectual disability and language impair-
ment (e.g., functional language by age 5 years is a good prognostic sign) and additional
mental health problems. Epilepsy, as a comorb id diagnosis, is associated with greater in-
tellectual disability and lower verbal ability.
Environmental. A variety of nonspecific risk factors, such as advanced parental age, low
birth weight, or fetal exposure to valproate, may contribute to risk of autism spectrum dis-
order.


Autism Spectrum Disorder 57
Genetic and physiological. Heritability estimates for au tism spectrum disorder have
ranged from 37% to higher than 90%, based on  twin concordance rates. Currently, as many
as 15% of cases of autism spec trum disorder appear  to be associated with a known genetic
mutation, with different  de novo copy number variants or de novo mutations in specific
genes associated with the disorder in differ ent families. However, even when an autism
spectrum disorder is associated with a know n genetic mutation, it does not appear to be
fully penetrant. Risk for the remainder of case s appears to be polygenic, with perhaps hun-
dreds of genetic loci making relatively small contributions.
Culture-Related Diagnostic Issues
Cultural differences will exist in norms for social interaction, no nverbal communication,
and relationships, but individuals with auti sm spectrum disorder are markedly impaired
against the norms for their cultural context. Cultural and socioeconomic factors may affect
age at recognition or diagnosis; for example, in the United Stat es, late or underdiagnosis of
autism spectrum disorder among Af rican American children may occur.
Gender-Related Diagnostic Issues
Autism spectrum disorder is di agnosed four times more often in males than in females. In
clinic samples, females tend to be more li kely to show accompanying intellectual disabil-
ity, suggesting that girls without accompan ying intellectual impairments or language
delays may go unrecognized, perhaps because of subtler manifestatio n of social and com-
munication difficulties.
Functional Consequences of  Autism Spectrum Disorder
In young children with autism spectrum diso rder, lack of social and communication abil-
ities may hamper learning, especially learning through social interaction or in settings


ities may hamper learning, especially learning through social interaction or in settings
with peers. In the home, insistence on rout ines and aversion to change, as well as sensory
sensitivities, may interfere with eating and sleeping and make routine care (e.g., haircuts,
dental work) extremely difficult. Adaptive skills are typically below measured IQ. Ex-
treme difficulties in planning, organization , and coping with change negatively impact
academic achievement, even fo r students with above-average intelligence. During adult-
hood, these indivi duals may have difficulties establishing independence because of con-
tinued rigidity and difficulty with novelty.
Many individuals with autism spectrum d isorder, even without intellectual disability,
have poor adult psychosocial functioning as indexed by measures such as independent
living and gainful employment. Functional cons equences in old age are unknown, but so-
cial isolation and communication problems (e .g., reduced help-seeking) are likely to have
consequences for health in older adulthood.
Differential Diagnosis
Rett syndrome. Disruption of social interaction ma y be observed during the regressive
phase of Rett syndrome (typic ally between 1–4 years of age); thus, a substantial proportion
of affected young girls may ha ve a presentation that meets diagnostic criteria for autism
spectrum disorder. Howe ver, after this period, most individuals with Rett syndrome im-
prove their social communication skills, and auti stic features are no longer a major area of
concern. Consequently, autism spectrum disorder should be considered only when all di-
agnostic criteria are met.
Selective mutism. In selective mutism, early develo pment is not typically disturbed.
The affected child usually exhibits appropriate communication skills in certain contexts
and settings. Even in settings where the child is mute, social reciprocity is not impaired,


and settings. Even in settings where the child is mute, social reciprocity is not impaired,
nor are restricted or repetitive patterns of behavior present.


58 Neurodevelopmental Disorders
Language disorders and social (p ragmatic) communi cation disorder. In some forms
of language disorder, there may be problems  of communication an d some secondary so-
cial difficulties. However, specific language disorder is not usually associated with abnor-
mal nonverbal communication, no r with the presence of restricted, repetitive patterns of
behavior, interests, or activities.
When an individual shows impairment in social communication and social interactions
but does not show restricted and repetitive beha vior or interests, criteria for social (prag-
matic) communication disorder, instead of autism spectrum disorder, may be met. The di-
agnosis of autism spectrum disorder supersedes that of so cial (pragmatic) communication
disorder whenever the criteria for autism spectrum disorder  are met, and care should be
taken to enquire carefully regarding past or current restricted/repetitive behavior.
Intellectual disability (intellectual developmental disorder) wit hout autism spectrum
disorder. Intellectual disability without autism spectrum disorder may be difficult to
differentiate from autism spectrum disorder in very young children. Individuals with in-
tellectual disability who have not developed language or symbolic skills also present a
challenge for differential diagnos is, since repetitive behavior often occurs in such individ-
uals as well. A diagnosis of autism spectrum disorder in an indivi dual with intellectual
disability is appropriate when social communi cation and interaction are significantly im-
paired relative to the developmental level of the individual’s nonverbal skills (e.g., fine
motor skills, nonverbal problem solving). In cont rast, intellectual  disability is the appropri-
ate diagnosis when there is no apparent di screpancy between the le vel of social-commu-
nicative skills and other intellectual skills.
Stereotypic movement disorder. Motor stereotypies are among the diagnostic charac-


Stereotypic movement disorder. Motor stereotypies are among the diagnostic charac-
teristics of autism spectrum disorder, so an additional diagnosis of stereotypic movement
disorder is not given when such repetitive be haviors are better explained by the presence
of autism spectrum disorder. However, when stereotypies cause self-injury and become a
focus of treatment, both diagnoses may be appropriate.
Attention-deficit/hyperactivity disorder. Abnormalities of attention (overly focused or
easily distracted) are common in individuals with autism spectrum disorder, as is hy-
peractivity. A diagnosi s of attention-deficit/hyperactivity disord er (ADHD) should be
considered when attentional difficulties or hyperactivity exceeds that typically seen in in-
dividuals of comparable mental age.
Schizophrenia. Schizophrenia with childhood onset usually develops after a period of
normal, or near normal, development. A prod romal state has been described in which so-
cial impairment and atypical interests and belie fs occur, which could be confused with the
social deficits seen in autism spectrum d isorder. Hallucinations and delusions, which are
defining features of schizophrenia, are not features of autism spectrum disorder. How-
ever, clinicians must take into account the potential for individual s with autism spectrum
disorder to be concrete in their interpretati on of questions regarding the key features of
schizophrenia (e.g., “Do you he ar voices when no one is th ere?” ”Yes [on the radio]”).
Comorbidity
Autism spectrum disorder is frequently assoc iated with intellectual impairment and struc-
tural language disorder (i.e., an inability to  comprehend and construc t sentences with proper
grammar), which should be noted under the relevant specifiers when applicable. Many in-


grammar), which should be noted under the relevant specifiers when applicable. Many in-
dividuals with autism spectrum disorder have psychiatric sympto ms that do not form part of
the diagnostic criteria for the disorder (about 70% of individuals with autism spectrum dis-
order may have one comorbid mental disord er, and 40% may have two or more comorbid


the diagnostic criteria for the disorder (about 70% of individuals with autism spectrum dis-
order may have one comorbid mental disord er, and 40% may have two or more comorbid
mental disorders). When criteria for both ADHD and autism spectrum disorder are met, both
diagnoses should be given. This same principle applies to concurrent diagnoses of autism
spectrum disorder and developmental coordina tion disorder, anxiety disorders, depressive


Attention-Deficit/Hyperactivity Disorder 59
disorders, and other comorbid diagnoses. Among individuals who are nonverbal or have
language deficits, observable si gns such as changes in sleep or  eating and increases in chal-
lenging behavior should trigger an evaluation fo r anxiety or depression. Specific learning dif-
ficulties (literacy and numeracy ) are common, as is developm ental coordination disorder.
Medical conditions commonly associated with autism spectrum disorder should be noted
under the “associated with a known medical/ge netic or environmental/acquired condition”
specifier. Such medical conditions include epilepsy, sleep proble ms, and constipation.
Avoidant-restrictive food intake disorder is a fairly frequent presenting feature of autism
spectrum disorder, and extreme and na rrow food preferences may persist.
Attention-Deficit/Hyperactivity
Disorder
Attention-Deficit/Hyperactivity Disorder
Diagnostic Criteria
A. A persistent pattern of inattention and/or hyperactivity-impulsivity that interferes with
functioning or development, as characterized by (1) and/or (2):
1.Inattention:  Six (or more) of the following symptoms have persisted for at least
6 months to a degree that is inconsistent with developmental level and that nega-
tively impacts directly on social and academic/occupational activities:
Note:  The symptoms are not solely a manifestation of oppositional behavior, defi-
ance, hostility, or failure to understand tasks or instructions. For older adolescents
and adults (age 17 and older), at least five symptoms are required.
a. Often fails to give close attention to details or makes careless mistakes in
schoolwork, at work, or during other activities (e.g., overlooks or misses details,
work is inaccurate).


work is inaccurate).
b. Often has difficulty sustaining attention in tasks or play activities (e.g., has diffi-
culty remaining focused during lectures, conversations, or lengthy reading).
c. Often does not seem to listen when spoken to directly (e.g., mind seems else-
where, even in the absence of any obvious distraction).
d. Often does not follow through on instructions and fails to finish schoolwork,
chores, or duties in the workplace (e.g., starts tasks but quickly loses focus and
is easily sidetracked).
e. Often has difficulty organizing tasks and activities (e.g., difficulty managing se-
quential tasks; difficulty keeping materials and belongings in order; messy, dis-
organized work; has poor time management; fails to meet deadlines).
f. Often avoids, dislikes, or is reluctant to engage in tasks that require sustained
mental effort (e.g., schoolwork or hom ework; for older adolescents and adults,
preparing reports, completing form s, reviewing lengthy papers).
g. Often loses things necessary for tasks or activities (e.g., school materials, pen-
cils, books, tools, wallets, keys, paperwork, eyeglasses, mobile telephones).
h. Is often easily distracted by extraneous stimuli (for older adolescents and
adults, may include unrelated thoughts).
i. Is often forgetful in daily activities (e.g., doing chores, running errands; for older
adolescents and adults, returning calls, paying bills, keeping appointments).


60 Neurodevelopmental Disorders
2.Hyperactivity and impulsivity:  Six (or more) of the following symptoms have per-
sisted for at least 6 months to a degree that is inconsistent with developmental level
and that negatively impacts directly on social and academic/occupational activities:
Note:  The symptoms are not solely a manifestation of opposition al behavior, defi-
ance, hostility, or a failure to understand tasks or instructions. For older adolescents
and adults (age 17 and older), at least five symptoms are required.
a. Often fidgets with or taps hands or feet or squirms in seat.
b. Often leaves seat in situations when remaining seated is expected (e.g., leaves
his or her place in the classroom, in the office or other workplace, or in other
situations that require remaining in place).
c. Often runs about or climbs in situations where it is inappropriate. ( Note:  In ad-
olescents or adults, may be limited to feeling restless.)
d. Often unable to play or engage in leisure activities quietly.
e. Is often “on the go,” acting as if “driven by a motor” (e.g., is unable to be or un-
comfortable being still for extended time, as in restaurants, meetings; may be
experienced by others as being restless or difficult to keep up with).
f. Often talks excessively.
g. Often blurts out an answer before a question has been completed (e.g., com-
pletes people’s sentences; cannot wait for turn in conversation).
h. Often has difficulty waiting his or her turn (e.g., while waiting in line).
i. Often interrupts or intrudes on others (e.g., butts into conversations, games, or
activities; may start using other people’s things without asking or receiving per-


activities; may start using other people’s things without asking or receiving per-
mission; for adolescents and adults, may intrude into or take over what others
are doing).
B. Several inattentive or hyperactive-impulsive symptoms were present prior to age
12 years.
C. Several inattentive or hyperactive-impulsive symptoms are present in two or more set-
tings (e.g., at home, school, or work; with friends or relatives; in other activities).
D. There is clear evidence that the symptoms interfere with, or reduce the quality of, so-
cial, academic, or occupational functioning.
E. The symptoms do not occur exclusively during the course of schizophrenia or another
psychotic disorder and are not better explai ned by another mental disorder (e.g., mood
disorder, anxiety disorder, dissociative diso rder, personality disorder, substance intox-
ication or withdrawal).
Specify whether:
314.01 (F90.2) Combined presentation:  If both Criterion A1 (inattention) and Crite-
rion A2 (hyperactivity-impulsivity) are met for the past 6 months.
314.00 (F90.0) Predominantly inattentive presentation:  If Criterion A1 (inattention)
is met but Criterion A2 (hyperactivity-impulsivity) is not met for the past 6 months.
314.01 (F90.1) Predominantly hyperactive/impulsive presentation:  If Criterion A2 (hy-
peractivity-impulsivity) is met and Criterion A1 (inattention) is not met for the past 6 months.
Specify if:
In partial remission:  When full criteria were previously met, fewer than the full criteria


In partial remission:  When full criteria were previously met, fewer than the full criteria
have been met for the past 6 months, and the symptoms still result in impairment in
social, academic, or occupational functioning.
Specify current severity:
Mild:  Few, if any, symptoms in excess of those required to make the diagnosis are
present, and symptoms result in no more than minor impairments in social or occupa-
tional functioning.
Moderate: Symptoms or functional impairment between “mild” and “severe” are present.


Attention-Deficit/Hyperactivity Disorder 61
Severe:  Many symptoms in excess of those required to make the diagnosis, or several
symptoms that are particularly severe, are present, or the symptoms result in marked
impairment in social or occupational functioning.
Diagnostic Features
The essential feature of attent ion-deficit/hyperactivity disorder (ADHD) is a persistent
pattern of inattention and/or hyperactivity-impulsivity that interferes with functioning or
development. Inattention  manifests behaviorally in ADHD as wandering off task, lacking
persistence, having difficulty sustaining focus, and being disorganized and is not due to
defiance or lack of comprehension. Hyperactivity  refers to excessive motor activity (such as
a child running about) when it is not appropriat e, or excessive fidgeting, tapping, or talk-
ativeness. In adults, hyperactivity may manife st as extreme restlessness or wearing others
out with their activity. Impulsivity  refers to hasty actions that  occur in the moment without
forethought and that have high potential for harm to the individual (e.g., darting into the
street without looking). Impulsivity may reflec t a desire for immediate rewards or an in-
ability to delay gratification.  Impulsive behaviors may manifest as social intrusiveness
(e.g., interrupting others excessively) and/ or as making important decisions without con-
sideration of long-term consequences (e.g., taking a job without ad equate information).
ADHD begins in childhood. The requirement that several symptoms  be present before
age 12 years conveys the importance of a substantial clinical presentation during child-
hood. At the same time, an earlier age at onset is not specified because of difficulties in es-
tablishing precise childhood onset retrospectively. Adult recall of childhood symptoms


tablishing precise childhood onset retrospectively. Adult recall of childhood symptoms
tends to be unreliable, and it is bene ficial to obtain ancillary information.
Manifestations of the disorder must be presen t in more than one setting (e.g., home and
school, work). Confirmation of substantial symptoms across settings typically cannot be
done accurately without consulting informants who have seen the individual in those set-
tings. Typically, symptoms vary depending on context within a given setting. Signs of the
disorder may be minimal or absent when the individual is receiving frequent rewards for
appropriate behavior, is under close supervision,  is in a novel setting, is engaged in espe-
cially interesting activities, has consistent exte rnal stimulation (e.g., via electronic screens),
or is interacting in one-on-one situa tions (e.g., the clinician's office).
Associated Features Supporting Diagnosis
Mild delays in language, motor,  or social development are not specific to ADHD but often co-
occur. Associated features may in clude low frustration tolerance, irritability, or mood lability.
Even in the absence of a specific learning disorder, academic or work performance is often im-
paired. Inattentive behavior is associated with various underlying cognit ive processes, and in-
dividuals with ADHD may exhibit cognitive pr oblems on tests of attention, executive
function, or memory, although these tests are not suff iciently sensitive or specific to serve as di-
agnostic indices. By early adulthood, ADHD is a ssociated with an increased risk of suicide at-
tempt, primarily when comorbid with mood, conduct, or substance use disorders.
No biological marker is diagnostic for AD HD. As a group, compared with peers, chil-
dren with ADHD display incr eased slow wave electroenc ephalograms, reduced total


dren with ADHD display incr eased slow wave electroenc ephalograms, reduced total
brain volume on magnetic resonance imaging, and possibly a delay in posterior to anterior
cortical maturation, but thes e findings are not diagnostic . In the uncommon cases where
there is a known genetic cause (e.g., Fragile  X syndrome, 22q11 deletion syndrome), the
ADHD presentation should still be diagnosed.
Prevalence
Population surveys sugge st that ADHD occurs in most cultures in about 5% of children


ADHD presentation should still be diagnosed.
Prevalence
Population surveys sugge st that ADHD occurs in most cultures in about 5% of children
and about 2.5% of adults.


62 Neurodevelopmental Disorders
Development and Course
Many parents first observe excessive motor activity when the child is a toddler, but symp-
toms are difficult to distinguish from highly  variable normative be haviors before age 4
years. ADHD is most often identified during elementary school years, and inattention be-
comes more prominent and impairing. The disord er is relatively stable through early ad-
olescence, but some individuals have a worsened course wi th development of antisocial
behaviors. In most individuals with ADHD , symptoms of motoric hyperactivity become
less obvious in adolescence and adulthood, bu t difficulties with restlessness, inattention,
poor planning, and impulsivity persist. A subs tantial proportion of children with ADHD
remain relatively impa ired into adulthood.
In preschool, the main manifestation is hyperactivity. Inattentio n becomes more prom-
inent during elementary school. During adoles cence, signs of hypera ctivity (e.g., running
and climbing) are less common and may be conf ined to fidgetiness or an inner feeling of
jitteriness, restlessness, or im patience. In adulthood, along wi th inattention and restless-
ness, impulsivity may remain problematic ev en when hyperactivity has diminished.
Risk and Prognostic Factors
Temperamental. ADHD is associated with reduced be havioral inhibition, effortful con-
trol, or constraint; negative emotionality; an d/or elevated novelty seeking. These traits
may predispose some children to ADHD bu t are not specific to the disorder.
Environmental. Very low birth weight (less than 1,500 grams) conveys a two- to three-
fold risk for ADHD, but most children with low birth weig ht do not develop ADHD. Al-
though ADHD is correlated with smoking du ring pregnancy, some of this association


though ADHD is correlated with smoking du ring pregnancy, some of this association
reflects common genetic risk. A minority of c ases may be related to reactions to aspects of
diet. There may be a history of child abuse, neglect, multiple  foster placements, neurotoxin
exposure (e.g., lead), infectio ns (e.g., encephalitis), or alcohol exposure in utero. Exposure
to environmental toxicants has been correlat ed with subsequent ADHD, but it is not
known whether these associations are causal.
Genetic and physiological. ADHD is elevated in the firs t-degree biological relatives of
individuals with ADHD. The heritability of AD HD is substantial. While specific genes
have been correlated with ADHD, they are ne ither necessary nor sufficient causal factors.
Visual and hearing impairments, metabolic abnormalities, sleep  disorders, nutritional de-
ficiencies, and epilepsy should be considered as possible influences on ADHD symptoms.
ADHD is not associated with specific physic al features, although  rates of minor phys-
ical anomalies (e.g., hypertelorism, highly arched palate, low-set ears) may be relatively
elevated. Subtle motor delays and other neur ological soft signs may occur. (Note that
marked co-occurring clumsiness and motor delays should be coded separately [e.g., de-
velopmental coordina tion disorder].)
Course modifiers. Family interaction patterns in ea rly childhood are unlikely to cause
ADHD but may influence its course or contri bute to secondary development of conduct
problems.
Culture-Related Diagnostic Issues
Differences in ADHD prevalence rates across re gions appear attributable mainly to differ-
ent diagnostic and methodological practices. However, there also may be cultural varia-
tion in attitudes toward or interpretations of children’s behaviors. Clinical identification


tion in attitudes toward or interpretations of children’s behaviors. Clinical identification
rates in the United States for African Americ an and Latino populations tend to be lower
than for Caucasian populations. Informant symptom ratings may be influenced by cul-
tural group of the child and the informant, su ggesting that culturally appropriate practices
are relevant in assessing ADHD.


Attention-Deficit/Hyperactivity Disorder 63
Gender-Related Diagnostic Issues
ADHD is more frequent in males than in fema les in the general population, with a ratio of
approximately 2:1 in children and 1.6:1 in ad ults. Females are more likely than males to
present primarily with inattentive features.
Functional Consequences of
Attention-Deficit/Hy peractivity Disorder
ADHD is associated with reduced school performance and academic attainment, social re-
jection, and, in adults, poorer occupation al performance, attainment, attendance, and
higher probability of unemployment as well as elevated interpersonal conflict. Children
with ADHD are significantly more likely than  their peers without ADHD to develop con-
duct disorder in adolescence and antisocial  personality disorder in adulthood, conse-
quently increasing the likelihood for substance use disorders and incarceration. The risk of
subsequent substance use disorders is elevated, especially when conduct disorder or an-
tisocial personality disorder develops. Individuals with ADHD are more likely than peers
to be injured. Traffic accidents and violatio ns are more frequent in drivers with ADHD.
There may be an elevated likelihood of  obesity among individuals with ADHD.
Inadequate or variable self-app lication to tasks that require sustained effort is often in-
terpreted by others as laziness , irresponsibility, or failure to  cooperate. Family relation-
ships may be characterized by discord and ne gative interactions. Peer relationships are
often disrupted by peer rejection, neglect, or  teasing of the individual with ADHD. On av-
erage, individuals with ADHD obtain less schooling, have poorer vocational achievement,
and have reduced intellectual scores than their peers, although there is great variability. In
its severe form, the disorder is markedly impairing, affecting social, familial, and scholas-
tic/occupational adjustment.


tic/occupational adjustment.
Academic deficits, school-relat ed problems, and peer neglect tend to be most associ-
ated with elevated symptoms of  inattention, whereas peer reje ction and, to a lesser extent,
accidental injury are most salient with mark ed symptoms of hyperactivity or impulsivity.
Differential Diagnosis
Oppositional defiant disorder. Individuals with oppositional defiant disorder may re-
sist work or school tasks that require self-application because they resist conforming to
others' demands. Their behavior is characte rized by negativity, hostility, and defiance.
These symptoms must be differentiated from aversion to school or mentally demanding
tasks due to difficulty in sustaining mental effort, forgetting instructions, and impulsivity
in individuals with ADHD. Complicating the di fferential diagnosis is the fact that some
individuals with ADHD may develop secondary oppositional attitudes toward such tasks
and devalue their importance.
Intermittent explosive disorder. ADHD and intermittent expl osive disorder share high
levels of impulsive behavior. However, indi viduals with intermitte nt explosive disorder
show serious aggression toward others, which is not characteristic of ADHD, and they do
not experience problems with sustaining atte ntion as seen in ADHD. In addition, intermit-
tent explosive disorder is rare in childhood. Intermittent explosive disorder may be diag-
nosed in the presence of ADHD.
Other neurodevelopmental disorders. The increased motoric acti vity that may occur in
ADHD must be distinguished from the repetiti ve motor behavior that  characterizes stereo-
typic movement disorder and some cases of autism spectr um disorder. In stereotypic
movement disorder, the motoric be havior is generally fixed and repetitive (e.g., body rock-
ing, self-biting), whereas the fidgetiness and restlessness in ADHD are typically general-


ized and not characterized by repetitive ster eotypic movements. In Tourette’s disorder,


64 Neurodevelopmental Disorders
frequent multiple tics can be mistaken for the generalized fidgetiness of ADHD. Prolonged
observation may be needed to differentiate fidgetiness from bouts of multiple tics.
Specific learning disorder. Children with specific learning disorder may appear inat-
tentive because of frustration, lack of interest, or limited ab ility. However, inattention in
individuals with a specific learning disorder  who do not have ADHD is not impairing out-
side of academic work.
Intellectual disability (intell ectual developmental disorder). Symptoms of ADHD are
common among children placed in academic sett ings that are inappropriate to their intel-
lectual ability. In such cases, the symptoms are not evident during non-academic tasks. A
diagnosis of ADHD in intellectual disability requires that inattention or hyperactivity be
excessive for mental age.
Autism spectrum disorder. Individuals with ADHD and those with autism spectrum
disorder exhibit inattention, social dysfunction, and difficult-to-manage behavior. The so-
cial dysfunction and peer rejection seen in individuals with ADHD must be distinguished
from the social disengagement, isolation, an d indifference to facial and tonal communica-
tion cues seen in individuals with autism sp ectrum disorder. Childr en with autism spec-
trum disorder may display tantru ms because of an inability to tolerate a change from their
expected course of events. In contrast, child ren with ADHD may misbehave or have a tan-
trum during a major transition because of impulsivity or poor self-control.
Reactive attachment disorder. Children with reactive attachment disorder may show
social disinhibition, but not the full ADHD symptom cluster, and display other features
such as a lack of enduring relationship s that are not characteristic of ADHD.
Anxiety disorders. ADHD shares symptoms of inattent ion with anxiety disorders. Indi-


Anxiety disorders. ADHD shares symptoms of inattent ion with anxiety disorders. Indi-
viduals with ADHD are inattentive because of their attraction to external stimuli, new
activities, or preoccupation with  enjoyable activities. This is distinguished from the inat-
tention due to worry and rumination seen in anxiety disorders. Restlessness might be seen
in anxiety disorders. Howeve r, in ADHD, the symptom is not associated with worry and
rumination.
Depressive disorders. Individuals with depressive diso rders may present with inabil-
ity to concentrate. However,  poor concentration in mood disorders becomes prominent
only during a depressive episode.
Bipolar disorder. Individuals with bipola r disorder may have increased activity, poor
concentration, and increased impulsivity, bu t these features are episodic, occurring sev-
eral days at a time. In bipolar disorder, increased impulsivity or inattention is accompa-
nied by elevated mood, grandiosity, and ot her specific bipolar features. Children with
ADHD may show significant changes in mood within the same day; such lability is dis-
tinct from a manic episode, which must last 4 or more days to be a clinical indicator of bi-
polar disorder, even in childre n. Bipolar disorder is rare in preadolescents, even when
severe irritability and anger are prominent,  whereas ADHD is common among children
and adolescents who display excessive anger and irritability.
Disruptive mood dysregulation disorder. Disruptive mood dysregulation disorder is
characterized by pervasive irritability, and intolerance of frustratio n, but impulsiveness
and disorganized attention are not essential features. However, most  children and adoles-
cents with the disorder have symptoms that also meet crit eria for ADHD, which is diag-
nosed separately.


nosed separately.
Substance use disorders. Differentiating ADHD from su bstance use disorders may be
problematic if the first presentation of ADHD symptoms follows the onset of abuse or fre-
quent use. Clear evidence of ADHD before su bstance misuse from informants or previous
records may be essential for differential diagnosis.