Controversies in autism
Controversies in autism encompass the disagreement over the exact nature of autism, its causes and manifestations; however it is generally considered to be a neurodevelopmental condition which manifests itself in markedly abnormal social interaction, communication ability, patterns of interests,lack of imagination, particularly evident in pretend play and other patterns of behavior.
The diagnostic criteria for autism differs from that of Asperger syndrome (AS).   The diagnostic process in either case is usually assessed through psychiatric and cognitive evaluation methods with IQ score indicating particular patterns of abilities (common to those with autism and generally infrequent in the non-autistic population) and to distinguish autism from psychiatric conditions. In the case of classical autism this assessment usually also involves an interview of carers and the client or, where interview is not possible, observation of the client. In the case of adults suspected of having classical autism, carers, where their report would be deemed feasible and reliable, would usually be interviewed about the person's early infancy. By contrast, AS is often not diagnosed until mid-childhood and even into adulthood, so interview about early infancy may not be necessary to a diagnosis.
The cause(s) of autism and the spectrum of pervasive developmental disorders (PDDs) are as yet either unknown or unclear in all cases, as are the prognoses, or best treatment options. There is, however, widespread agreement that early diagnosis and intervention can often make a significant difference for the long-term prospects of a person with autism because the human mind and nervous system are more plastic at a younger age; therefore, research for possible therapies and treatments is often focused toward children who have been diagnosed early with a spectrum disorder.

# Usefulness and accuracy of autism diagnosis
The 1994 DSM-IV criteria for the diagnosis of autism are the result of several revisions, and consequently the psychiatric community is divided as to whether the condition should be ordered by severity along a spectrum or categorised into multiple distinct disorders that have similar symptoms. This division is exacerbated by the wide range of co-morbid conditions effecting a significant proportion of those with autism spectrum disorders. Research and clinical experience suggests however, that while autism can appear to manifest as a psychiatric disorder, psychiatric co-morbidities aside, its underlying causes are largely neurological.
A diagnosis of autism is complicated by the fact that there is no definitive test for autism due to the significant variance of symptoms among people with autistic traits, as well as a lack of knowledge about the etiology of the condition. Whilst a majority of those with Asperger syndrome may be highly functional cognitively but lack 'social' skills, a majority of those with so-called "profound autism" may be non-verbal and deficient in elementary skills. Some autistic people are considered mentally retarded, having low IQs (Intelligence Quotients). Others have been ultimately found to have average or above average intelligence. To complicate this some with high IQs have had severe functioning challenges whilst some with low IQs (under 70) have had significant skills and a minority of people with autism have narrow, but exceptional savant abilities.
Treatment strategies and choices are based on definitions of what is perceived as needing to be changed. Different treatment approaches have had widely divergent outcomes for different individuals. As a result, some parents claim their children recovered with only behavioral approaches, some credit biomedical intervention as the best method for improvement, others claim success with interventions for sensory-perceptual disorders or augmented communication technique (or combinations). Others report little or no progress after trying many different approaches. Occasionally, parents claim their autistic children have simply "grown out of it."
There are also those (primarily those on the autistic spectrum themselves) who reject the premise that autism is necessarily a disorder that should be cured. In their view, a diagnosis can sometimes result from a judgment of non-conformity that is followed by efforts to correct what are essentially personality traits.

## Asperger syndrome and autism
Currently, Asperger's syndrome is classified as a separate diagnosis from autism in the DSM-IV, but it is still considered an autism spectrum disorder. The primary distinction between the definitions of autism and Asperger's Syndrome in the DSM-IV is that autism involves a significant speech delay by the age 3-4 and is less common in those with Asperger's. Some people believe autism and Asperger's syndrome should not be given separate labels in the DSM-IV because they believe that differences in language acquisition are not significant enough to separate the disorders or that autism and Asperger's have few definitive differences. It is also unclear whether a child with high-functioning autism who learns to speak should have their diagnosis changed to that of Asperger's Syndrome, though it should be noted that late speech does occur in a minority of neurotypical children and, in itself, need not be indicative of autism in a child with Asperger's Syndrome who goes on to develop good functional language.

# 'Autistic' vs. 'has autism'
Some people diagnosed on the autism spectrum have a preference for the word autistic to be used as both an adjective and a noun; they dislike the politically correct person-first terminology, person with autism. Person-first terminology remains the preferred form in most clinical literature about autism.

# Epidemiology of autism
There is uncertainty and controversy over whether the incidence of autism is actually increasing or if there simply is an increase in the number of reported cases and better diagnosis. Some argue that if the incidence is rising, then environmental factors play a greater role; if it is simply being reported more often, genetics deserves more attention. One theory, particularly associated with Simon Baron-Cohen, suggests that increased social mobility and assortative mating may lead to the genetic amplification of autistic traits.
Anecdotal reports from school districts and physicians lend support to the impression that the incidence is rising, and some studies appear to support this as well. Some believe the incidence has risen markedly in the last few years, from about one in 5000 to estimates ranging between one in 400 or even as high as one in 166, which may indicate a major societal problem. In the United States, Centers for Disease Control (CDC) have vacillated between the latter two figures. In January of 2004 the CDC sent out an autism alarm to all pediatricians stating that they believed that 1 in 166 children had an autism spectrum disorder and as common as one in six now suffered from a neurodevelopmental or behavioral disorder. (Others have quoted these figures as high as 1 in 40 for autism and one in three for the neurodevelopmental or behavioral disorders.)
Among the factors cited likely to cause increased reporting are the broadening definition of autism, which began most markedly with revised classifications in DSM-III-R in 1987 and the greater availability of services for autistic individuals creating an incentive to be inclusive in the diagnosis. Secondly, the last few decades have seen a greater awareness of autistic traits among pediatricians and other medical specialists. It is surmised that the types of children diagnosed as infants prior to the 1970s as retarded, emotionally disturbed or psychotic are now diagnosed as autistic or having PDD. Today Childhood Schizophrenia is distinguished from autism by later age of onset and the presence or absence of persistent hallucinations, between 1800-1938, Autism was believed to be related to childhood schizophrenia.

# Genetics and autism
There is evidence that autism has a genetic component, and ongoing research focuses on finding the biomarkers that determine autistic phenotypes. One, as yet unproven theory is that there may be genes which contribute to a vulnerability to environmental triggers or have another role in the etiology of autism.
There is a trend in research towards viewing genetics as an underlying factor. However, whilst some parents of those with autism are progressively also being diagnosed on the autism spectrum, at least some autistic children have apparently neurotypical parents. This suggests that genetics are either not a necessary cause or that they don't play a part in all cases of ASD. The spectrum of autistic disorders is notable for its significant gender disparity, with the incidence of autism in males greatly exceeding the incidence in females. Whilst this could argue against a genetic theory, it has also been argued that male brains may be more vulnerable during early development.  Conversely, some studies have suggested that testosterone potentiates the toxic effects of mercury, and this has also been cited by some interest groups to account for the gender difference along non-genetic lines.
Scientists have recently (July 2005) shown that variations in the gene for protein kinase C beta 1 (PRKCB1), a protein with an important role in brain function, are strongly associated with autism.  This find may suggest some answers to a number of previous, but unexplained, observations about autism and provides the potential for a mechanistic explanation for some of the characteristics of the condition.
A book by Jay Joseph released in 2006 denies the genetic evidence:

## Implications of genetic testing
If and when genetic testing for autism becomes available, it is anticipated that many women pregnant with an autistic child will decide to abort the pregnancy.

# Vaccines and autism
Several controversial claims have been made with regard to autism and vaccinations.None of these claims have been verified to date.

## Thimerosal

## MMR triple vaccine

# Intelligence and autism
The determination of 'mental retardation' is based on IQ testing, which has its own set of controversies and detractors.  Whilst a majority of children diagnosed with autism before the increased incidence of 'high-functioning' autism and the recognition of Asperger syndrome may have been assessed with low IQ scores associated with presumed mental retardation, this correlation is questionable when applied to those across the entire diversity of the autism spectrum.
Verbal IQ is sometimes used to distinguish between autism and Asperger syndrome. In addition, autistic individuals who score over 70 on an IQ test are sometimes labeled as "high functioning."  IQ score is sometimes used to determine an autistic person's eligibility for services. The use of IQ as a criterion can be problematic because some autistic people might be considered "high functioning" overall while still needing help with specific tasks.
It has been suggested in recent scientific literature that mainstream intelligence tests do not accurately measure the cognitive abilities of autistics because autistic cognition differs from typical human cognition. According to the Association for Psychological Science, a 2007 study by Dawson et al. suggested that Raven's Progressive Matrices, a test of abstract reasoning, may be a better indicator of intelligence for autistic children than the more commonly used Wechsler Intelligence Scale for Children.  Researchers suspected that the WISC relied too heavily on language to be an accurate measure of intelligence for autistics.  They administered both tests to neurotypical and autistic children.  The neurotypical children scored similarly on both tests, but the autistic children fared far better on the RPM than on the WISC.
This study contradicts the widely held but never proven assumption that autistics suffer from cognitive deficits in high-level abstract thinking.  The RPM is considered a "paradigmatic measure" of abstract, general and fluid reasoning, which is precisely the ability autistics have been presumed to lack. This theory would predict that autistics fare dramatically worse on the RPM than on other measures of intelligence, whereas Dawson et al. showed that the opposite is true.
An alternative view is that autism and intelligence are unrelated; all levels of intelligence have been observed in those with autism. According to this view, those with autism and low intelligence would be more likely to be recognized and diagnosed, and those with normal to high intelligence might be better able to articulate their experiences (either verbally or through writing) and would be labeled as high-functioning regardless of their other neurological deficits. Many autism rights activists oppose the use of intelligence testing altogether, as they believe too much emphasis is placed on IQ within autism.
A recent review questioned the validity of IQ testing of autistic people. As those with normal or high intelligence are less likely to be diagnosed with autism, the average IQ of the autistic community as a whole may not be able to be reliably determined. Furthermore, anecdotal accounts of autistic children whose IQ scores have increased dozens of points over a relatively short period of time are not uncommon. Some of these cases, however, may not correspond to an increase in actual intelligence, however; perhaps, as with neurotypical children, children with autism may simply get better at taking IQ tests (the so-called practice effect).
In the early 1990s, autism was still largely synonymous with the concept of a singular 'low functioning' disorder. The progressive publication of autistic individuals' autobiographical works caused public perceptions to change. The increased prevalence of  personal accounts of autism coincided with a greater interest in Hans Asperger's publications about Asperger's Syndrome which were only translated into English by Lorna Wing in 1981 and became popularised by her in 1992. As autism became recognized as a spectrum disorder, it lead to the recognition of 'high functioning' autistics. Presumably highly intelligent people with autism may have been more common than once imagined.
There is considerable anecdotal evidence that autistic individuals once thought to be mentally retarded have later been identified as very intelligent. Sue Rubin, writer of the film Autism Is a World was believed to be mentally retarded until age 13, after which she was tested to have an IQ of 131.
Characteristics observed by some studies as being associated with gifted children at least appear to be analogous to those of autistic children:
- Some studies suggest that gifted children are more than twice as introverted as their peers.
- Gifted children have been characterized as having obsessive interests, preferring to play alone, and enjoying solitude. They are also said to have prodigious memories and show intense reactions to noise, pain and frustration.
- According to some reports, gifted children have a higher-than-average propensity to allergies.

# Prognosis for autistic children
Children who are diagnosed with autism face a great range of outcomes. Some have appeared to 'outgrow' much of the extremity of their autism spontaneously by mid childhood. Others have appeared to become significantly less autistic after one or a range of different mainstream and non-mainstream interventions. Many become mainstreamed and achieve employment skills and some level of independent living after years of hard work and intensive training and others remain in special education and later move into residential care facilities. Some develop slowly, but never lose their diagnoses. Some may appear less autistic during childhood and report becoming "more autistic" or 'regressing' in adulthood. Some, for any variety of reasons, may fail to develop many more skills than they had in infancy.
While some people see early intervention as crucial for autism, the prognosis is also less certain the younger the child is meaning it may be impossible to clearly attribute improvement to the intervention itself. An idiosyncratic development path may also be confused with a more severe disorder, and the child may 'catch up' on his/her own. Those with a range of untreated co-morbid conditions may be presumed more 'severely autistic' and either dramatically change once these are addressed or fail to progress if they are overlooked as part and parcel of 'untreatable autism'. Research indicates that the human mind and nervous system remains plastic for longer than originally thought, and people with autism, like those with learning disabilities, have been known to cognitively develop throughout their lives.
There is broad consensus in the medical community to the effect that autistic behaviors can be improved through training and through medical or educational interventions, though there is apparently no consensus on treatment regimes and objectives.

# Disorder vs. neurodiversity models
There is some controversy about which model of autism is correct: the model that autism is a disorder or the model that autism is a natural, even healthy, variation in neurological hardwiring.