Defining Autism Spectrum Disorders
Autism is a complex neurobehavioral disorder characterized by impairment in reciprocal social interaction, impairment in communication, and the presence of repetitive and stereotypic patterns of behaviors, interests, and activities. The onset of symptoms is typically before the age of 3 years. The severity of impairment in the given domains as well as the pattern of impairments varies from individual to individual; that is why diagnosticians refer to a “ spectrum ” of disability.
Impairment in social interaction range from difficulty initiating and maintaining interaction, impaired ability to recognize and experience emotions, and difficulty processing and appreciating the thoughts and feelings of others. Communication deficits range from no useful form of communication to very advanced language abilities, but little ability to use language in a social manner. Repetitive and stereotypic behaviors include perseverative behaviors such as complex rituals, extreme difficulty adapting to change and transition, and unusual movements such as hand flapping or whirling.
Autism is one diagnosis within the larger category of Pervasive Developmental Disorders described in the The Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition, Text Revision edition (DSM-IV, TR). Autism, along with related, but slightly different disorders of Aspergers Syndrome and Pervasive Developmental Disorder-Not Otherwise Specified, constitute the conditions commonly referred to as the Autism Spectrum Disorders. Two rare disorders, Rett Syndrome (a genetic disorder) and Disintegrative Disorder of Childhood are the other currently recognized pervasive developmental disorders.
Once thought to be very rare, autism spectrum disorders are estimated to occur in an many as 1: 88 (one in every 88 people).