Chapter 7 Autism Spectrum Disorders
(Pervasive Developmental Disorders)
PATHOPHYSIOLOGY
Autism spectrum disorders (ASDs), also known as pervasive developmental disorders, comprise a group of neuropsychiatric disabilities involving varying degrees of restricted, repetitive, and stereotyped patterns of behavior as well as impairment in communication skills and social interaction. ASD diagnoses range from the milder Asperger’s disorder to the more severe autistic disorder. The Diagnostic and Statistical Manual of Mental Disorders, fourth edition, text revision (DSM-IV-TR) outlines specific observable behavioral components related to social interactions, communication, and repetitive and stereotypical behaviors and other indicators, presented for Asperger’s disorder in Box 7-1 and autistic disorder in Box 7-2. Intact language skills distinguish Asperger’s disorder from autism. Rare forms of ASD include Rett syndrome (Box 7-3) and childhood disintegrative disorder (CDD) (Box 7-4). In both disorders there is normal development followed by a profound regression of cognitive abilities. Rett syndrome occurs only in girls and is likely genetically based. The DSM criteria for pervasive developmental disorder, not otherwise specified, are presented in Box 7-5.
Box 7-1 Diagnostic Criteria for Asperger’s Disorder
A. Qualitative impairment in social interaction, as manifested by at least two of the following:
B. Restricted repetitive and stereotyped patterns of behavior, interests, and activities, as manifested by at least one of the following:
C. The disturbance causes clinically significant impairments in social, occupational, or other important areas of functioning
D. There is no clinically significant general delay in language (e.g., single words used by age 2 years, communicative phrases used by age 3 years)
E. There is no clinically significant delay in cognitive development or in the development of age-appropriate self-help skills, adaptive behavior (other than social interaction), and curiosity about the environment in childhood
F. Criteria are not met for another specific pervasive developmental disorder of schizophrenia
From American Psychiatric Association: Diagnostic and statistical manual of mental disorders, ed 4, text revision (DSM-IV-TR), Washington, DC, 2000, The Association.
Box 7-2 Diagnostic Criteria for Autistic Disorder
A. A total of six (or more) items from (1), (2), and (3), with at least two from (1), and one each from (2) and (3)
B. Delays or abnormal functioning in at least one of the following areas, with onset before age 3 years:
C. The disturbance is not better accounted for by Rett syndrome or Childhood Disintegrative Disorder.
From American Psychiatric Association: Diagnostic and statistical manual of mental disorders, ed 4, text revision (DSM-IV-TR), Washington, DC, 2000, The Association.
Box 7-3 Diagnostic Criteria for Rett Syndrome (Females Only)
B. Onset of all of the following after a period of normal development:
From American Psychiatric Association: Diagnostic and statistical manual of mental disorders, ed 4, text revision (DSM-IV-TR), Washington, DC, 2000, The Association.
Box 7-4 Diagnostic Criteria for Childhood Disintegrative Disorder*
A. Apparently normal development for at least the first 2 years after birth as manifested by the presence of age-appropriate verbal and nonverbal communication, social relationships, play, and adaptive behavior
B. Clinically significant loss of previously acquired skills (before age 10 years in at least two of the following areas):
C. Abnormalities of functioning in at least two of the following areas: