Autism Spectrum Disorders

Autism is a neurological disorder that affects the ability of an individual to communicate, form relationships, and respond to the surrounding environment. Autism [Page 1150]was first identified in 1943 by Leo Kanner. Kanner described a group of young children in his care who shared certain behaviors very different from typical children. He described the children as isolated and aloof, with odd language patterns, engaging in seemingly meaningless repetitive behavior, and maintaining a strong desire for sameness in their environment.

Today, clinicians and physicians rely on the Diagnostic and Statistical Manual of Mental Disorders (4th edition; DSM-IV) when diagnosing students with autism. The DSM-IV identifies three essential areas of disturbance that lead to a diagnosis of autism: (1) disturbances in social interaction, (2) disturbances in communication, and (3) the presence of odd and persistent behaviors. Autism is defined within the DSM-IV as one of the pervasive developmental disorders. In addition to autistic disorder, often described as Kanner's autism or classic autism, four other disorders are grouped under pervasive developmental disorders: Rett's disorder, childhood disintegrative disorder, Asperger's disorder, and pervasive developmental disorder–not otherwise specified (PDD-NOS). All of the pervasive developmental disorders share a number of symptoms, which makes differential diagnosis extremely difficult. Rett's disorder is unique in that it affects only girls. Autism, on the other hand, affects predominantly boys, with a ratio of 4:1. Rett's disorder also differs from autism in that it is progressive and degenerative. Students with Rett's disorder demonstrate many of the same classic symptoms of autism across the social, communicative, and behavioral domains. However, they also display symptoms very specific to Rett's, including deceleration in head growth, severe seizure disorder, profound mental retardation, and awkward and clumsy gait.

Individuals diagnosed with childhood disintegrative disorder (CDD) demonstrate normal development for the first 2 to 4 years of life. This is then followed by a loss of skills across most areas of development, including language, social skills, and self-help skills. CDD is differentiated from the more classic autistic disorder by the age of onset and course of development. Prognosis for children diagnosed with CDD is believed to be less positive than for autism. CDD is considered quite rare, occurring much less frequently than autism.

Asperger's disorder is sometimes referred to as high-functioning autism. Students with Asperger's disorder demonstrate deficits in nonverbal aspects of communication, such as comprehending gestures or facial expressions, as well as significant deficits in social interaction. Other characteristics include a restricted range of interests and lack of motor coordination. Cognition and language abilities for students with Asperger's disorder typically test within normal limits.

PDD-NOS is the category within pervasive developmental disorders that identifies students with autistic symptoms who do not meet all criteria for any of the other categories. It is often viewed as the default diagnosis and may change as more information about a student becomes available. In most cases, students with PDD-NOS demonstrate a milder version of the classic autism symptoms.

Autistic disorder is diagnosed when the symptoms appear prior to the age of 3 years. Deficits in each of three key areas (social, communication, and behavior) must be evident. Approximately 50% to 60% of students with autism function within the range of mental retardation. Almost 40% of students with autism do not develop functional speech. Those who do develop speech often demonstrate echolalia (the repetition, either immediately or later in time, of what another person has said) and deficits in the spontaneous use of language.

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