Autism

Current Diagnostic Criteria

The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision (DSM-IV-TR), defines criteria for autistic disorder and PDD-not otherwise specified, as well as Rett's disorder, childhood disintegrative disorder, and Asperger's disorder. The diagnosis of autistic disorder in the DSM-IV-TR requires six symptoms, at least two of which are social, one communication, and one repetitive behavior/resistance to change. Rett's disorder is a severe disorder of early development, involving deterioration of motor and cognitive skills, occurring primarily in girls, and associated with a specific gene. Asperger's disorder shares the social and repetitive behaviors of autistic disorder but does not show early language delay or mental retardation. Childhood disintegrative disorder is a rare condition, in which severe autistic regression and poor outcome follows at least 2 years of normal development.

Diagnoses That Commonly Occur with Autism

Disorders that commonly occur with ASDs include mental retardation, anxiety, depression, tic disorders, and seizure disorders. Although the DSM-IV-TR does not allow for co-occurring diagnoses of autism and attention deficit hyperactivity disorder (ADHD), several recent studies demonstrate that ADHD symptoms are common in ASDs.

Characteristics

ASDs are characterized by an impaired ability to form normal relationships, deficits in the use of nonverbal forms of communication such as eye contact and gesture, lack of social reciprocity, poor awareness of others' reactions, and failure to share experiences with others. The back-and-forth of conversations appears to be an area of especially profound pragmatic language deficit. Social cognition (processing of social information), especially in the area of processing face identity and facially expressed emotion, is also consistently impaired.

Children with an ASD generally present with significant impairment in language functioning. Although some autistic children are mute, verbal autistic children are typically, though not always, able to acquire normal morphology, syntax, and phonology. However, development of language is usually delayed, and pragmatic, abstract, and inferential language is weak.

An overly narrow focus of attention characterizes ASDs; this narrow focus may contribute to the phenomenon of savant skills (exceptional ability in one area) and lead to extreme degrees of perseveration, routine-boundedness, resistance to changes in the environment, difficulty with divided attention tasks, and difficulty in shifting attention. Sustained attention, however, appears to be spared, at least under certain conditions. A theory of “weak central coherence,” in which top-down processing is impaired relative to bottom-up and perceptually dominated [Page 91]processing, has been proposed as an explanatory principle for the autism syndrome.

Executive functioning deficits (e.g., difficulties with organization, planning, flexibility, impulse control, working memory) are common in older children with an ASD. Younger children display such impairments less consistently. This suggests that such deficits do not explain core symptoms of ASDs, and are not universal in, or specific to, autism.

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