Autistic spectrum

Overview
The autism spectrum, also called autism spectrum disorders (ASD) or autism spectrum conditions (ASC), with the word autistic sometimes replacing autism, is a spectrum of psychological conditions characterized by widespread abnormalities of social interactions and communication, as well as severely restricted interests and highly repetitive behavior. A 2005 review estimated a prevalence of 6.0–6.5 per 1,000 for ASD. Of the various forms of ASD, pervasive developmental disorder not otherwise specified (PDD-NOS) was the vast majority, autism was at least 1.3 per 1,000, and Asperger syndrome was about 0.3 per 1,000; the atypical forms childhood disintegrative disorder and Rett syndrome were much rarer.

Classification
The three main forms of ASD are autism, Asperger syndrome, and PDD-NOS. Autism forms the core of the autism spectrum disorders. Asperger syndrome is closest to autism in signs and likely causes; unlike autism, Asperger's has no significant delay in language development. Pervasive developmental disorder not otherwise specified (PDD-NOS) is diagnosed when the criteria are not met for a more specific disorder. Some sources also include Rett syndrome and childhood disintegrative disorder, which share several signs with autism but may have unrelated causes; other sources combine ASD with these two conditions into the pervasive developmental disorders.

The terminology of autism can be bewildering. Autism, Asperger's and PDD-NOS are sometimes called the autistic disorders instead of ASD, whereas autism itself is often called autistic disorder, childhood autism, or infantile autism. Although the older term pervasive developmental disorder and the newer term autism spectrum disorder largely or entirely overlap, the former was intended to describe a specific set of diagnostic labels, whereas the latter refers to a postulated spectrum disorder linking various conditions. ASD, in turn, is a subset of the broader autism phenotype (BAP), which describes individuals who may not have ASD but do have autistic-like traits, such as avoiding eye contact.

Characteristics
The defining characteristics of autism spectrum disorders are qualitative impairments of social communication and interaction, along with restricted and repetitive activities and interests. Individual symptoms occur in the general population and appear not to associate highly, without a sharp line separating pathological severity from common traits. Other aspects of ASD, such as atypical eating, are also common but are not essential for diagnosis; they can affect the individual or the family.

An estimated 0.5% to 10% of individuals with ASD show unusual abilities, ranging from splinter skills such as the memorization of trivia to the extraordinarily rare talents of prodigious autistic savants.

Contrary to common belief, children with autism do not prefer to be alone. Making and maintaining friendships often proves to be difficult for those with autism. For them, the quality of friendships, not the number of friends, predicts how lonely they are. Being on the autism spectrum does not keep children from understanding race and gender stereotypes in a society; like normal children they learn stereotypes by observing their parents' actions, such as locking car doors when in certain neighborhoods.

Management
The main goals of treatment are to lessen associated deficits and family distress, and to increase quality of life and functional independence. No single treatment is best and treatment is typically tailored to the child's needs. Intensive, sustained special education programs and behavior therapy early in life can help children acquire self-care, social, and job skills. Available approaches include applied behavior analysis (ABA), developmental models, structured teaching, speech and language therapy, social skills therapy, and occupational therapy.

Epidemiology
Most recent reviews tend to estimate a prevalence of 1–2 per 1,000 for autism and close to 6 per 1,000 for ASD; because of inadequate data, these numbers may underestimate ASD's true prevalence. PDD-NOS is the vast majority of ASD, Asperger's is about 0.3 per 1,000 and the remaining ASD forms are much rarer. The number of reported cases of autism increased dramatically in the 1990s and early 2000s. This increase is largely attributable to changes in diagnostic practices, referral patterns, availability of services, age at diagnosis, and public awareness, though as-yet-unidentified contributing environmental risk factors cannot be ruled out.