Pervasive Developmental Disorders is a DSM-IV category of childhood disorders characterized by severe deﬁcits in communication, impaired social skills, repetitive, stereotyped movements, and unusual preoccupations and interests. These are also known as the autism spectrum disorders, and they occur in ten to twenty children per 10,000 births. Of those, about half have autistic disorder (autism), which is the most severe form of the disorder. These disorders usually manifest during the ﬁrst several years of life, and are often associated with some degree of mental retardation.
In addition to autism and Asperger syndrome, this category also includes Rett’s disorder (also known as Rett’s syndrome), which is usually comorbid with severe or profound mental retardation. Rett’s disorder is characterized by the development of multiple deﬁcits by a child who was previously functioning normally since birth. Psychological and motor development are normal for at least the ﬁrst ﬁve months, but between that age and thirty months, there is a loss of previously acquired hand skills, accompanied by stereotyped hand-wringing movements. In the ﬁrst few years, interest in the social environment will also decrease steadily, and this is usually accompanied by a severe impairment in language development and motor coordination. Unlike other developmental disorders, this one occurs only in females. This may be for genetic reasons— a large proportion of girls with this syndrome have a mutation in the X chromosome.
Also in the Pervasive Developmental Disorder category is childhood disintegrative disorder, so called because the affected child begins life with at least two years of apparently normal development, including verbal and nonverbal communication, social and adaptive skills, and play habits. Before the age of ten, however, the child experiences a signiﬁcant loss of skills in at least two areas, including language, social skills, adaptive behavior, bowel/bladder control, play, or motor skills, with the result that the child appears to be autistic. When a child has a severe, pervasive impairment in social interaction, verbal/nonverbal communication, or shows stereotyped behavior, but doesn’t meet the diagnostic criteria for any of the other disorders in this category, the diagnosis given is “pervasive developmental disorder not otherwise speciﬁed.”
- American Psychiatric Association. DSM-IV-TR: Diagnostic and Statistical Manual of Mental Disorders. 4th ed. Text revision. Washington, DC: American Psychiatric Association, 2000.