Autism Spectrum Disorders in Young Children

The focus of this review is on the early identification, assessment, and treatment of young children (0–5 years of age) with autism spectrum disorders (ASDs). ASDs are diagnosed in approximately 1 out of 150 children in the United States,1,2 and given the increasing evidence that early intervention improves outcomes for children with ASD, there is an urgent need to enhance early detection and intervention efforts.3 Retrospective parent reports,4,5 early home videotapes,6,7 and newer prospective studies of younger siblings of children with ASD who are at elevated risk 8,9 provide converging evidence that the age at onset for the majority of cases of ASD is the second year of life. We first review the early signs and symptoms of ASD, then describe some of the measures that can be employed for screening and diagnosis, discuss the family context with respect to both adaptation to diagnosis and treatment, and conclude with a brief review of interventions for young children with ASD. Traditionally, the term pervasive developmental disorders (PDDs) has been employed in the Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision (DSM-IV-TR), referring to autistic disorder, Asperger's disorder, PDD not otherwise specified (PDD-NOS), childhood disintegrative disorder, and Rett Disorder.10 In this article, we use the term ASDs to refer to the diagnostic category of PDDs. Specifically, we focus on the diagnosis of autistic disorder (AD) and PDDNOS, as the majority of research on young children has focused on these conditions. Our preference for the term ASD reflects recognition that along with restrictive interests and repetitive behaviors, the primary developmental perturbations that characterize ASDs are social and communicative in nature. Moreover, the term ASD reflects an understanding that symptoms and behaviors in these three domains are best quantified as continuous phenomena.11 Although these behaviors lie on a continuum in the general population, individuals with ASD are characterized by severe and pervasive impairments in reciprocal social interaction and communication and exhibit stereotyped behaviors, as well as restricted interests, and activities. To meet full criteria for a DSM-IV diagnosis of AD, a child must demonstrate the following symptoms (Table 1): Qualitative impairment in social interaction as manifested by two of the following: impairment in the use of multiple nonverbal behaviors (eg, eye gaze, facial expression, body postures), failure to develop peer relationships, lack of sharing of enjoyment, or lack of social or emotional reciprocity. Qualitative impairment in communication in at least one of the following areas: delay or total lack of spoken language, marked impairment in the ability to initiate or sustain a conversation with others, stereotyped or repetitive use of language, or lack of varied spontaneous play. Restricted repetitive and stereotyped patterns of behaviors, interests, and activities as manifested by preoccupation with one or more restricted patterns of interests, inflexible adherence to nonfunctional routines or rituals, repetitive motor mannerisms, or preoccupation with parts of objects. Table 1 Diagnostic criteria for autistic disorder A diagnosis of PDD-NOS is assigned when the child does not meet full criteria for AD or any other ASD but has marked severe and pervasive impairment in the development of reciprocal social interaction skills and in communication skills or exhibits stereotyped behaviors.10 Particularly before the age of 3 years, distinctions between AD and PDD-NOS may be less meaningful due to low stability across these two disorders.12,13 Thus, when children receive a diagnosis of PDD-NOS or AD prior to age 3 years, they are likely to remain on the spectrum (albeit less likely than older children), but there is little specificity across these 2 conditions. A study suggests that up to 50% of PDD-NOS cases could have been overdiagnosed, whereas around 22% of cases were underdiagnosed.12 By the age of 4 years, the stability of diagnostics has shown to improve significantly (80%–88% stability rate) and is comparable to that observed in older children and adolescents.14,15 Prior to evaluating a young child, it is essential to be knowledgeable about normative infant and toddler development as well as other early emerging psychopathological conditions. This is particularly important with children under the age of 2 years, as delays or losses of age-appropriate social and communicative skills are often central to making a differential diagnosis of ASD.16–18 In addition, young children with extreme temperamental inhibition, other regulatory challenges, or anxiety disorders or those who have been exposed to trauma may be socially reticent in a novel setting with a new evaluator. Thus, they may evidence unusual eye contact and restricted pretend play and may even engage in repetitive behaviors. Therefore, in addition to learning the signs of ASD in young children, a firm grounding in normative development and infant-toddler mental health is requisite to reliable differential diagnosis.