There are five disorders that fall under the term autistic spectrum disorders:
Autism is a disorder characterized by impairments in social interaction, communication & language development, stereotyped, consistent movements & insistence on sameness in routines. Autism typically manifests itself during the first three years of life & results in a regression of previously attained skills.
Asperger Syndrome Asperger Disorder is characterized by impairments in social interactions & non-verbal communication behaviors. People with Asperger Syndrome may exhibit tendencies toward stereotyped behaviors, preoccupation with unique interests or parts of objects, & a desire to follow inflexible routines & schedules. Generally, people with Asperger Syndrome test in the range of average to above average intelligence.
Rett Syndrome Rett’s Disorder is characterized by typical development & milestones during the first few months of life. Around five months there is a marked deceleration of head growth accompanied by a loss of previously acquired h& skills followed by the development of stereotyped h& movements. People with Rett’s Disorder also exhibit severe psychomotor retardation & impaired language development.
Childhood Disintegrative DisorderFor people with CDD, there is a period of normal development & then a loss of previously acquired skills in at least two of the following areas, expressive or receptive language, social skills or adaptive behavior, bowel or bladder control, play, &/or motor skills.
Pervasive Developmental Disorder-Not Otherwise Specified PDD-NOS is commonly referred to as atypical autism. A diagnosis of PDD-NOS may be made when a child does not meet the diagnostic criteria for other autistic spectrum disorders but exhibits severe & pervasive impairment in communication, social interaction, & stereotyped behaviors. (American Psychiatric Association & Autism Society of America)