- Pervasive developmental disorder (PDD) is underrecognized because of lack of awareness of the wide range of severity and differing manifestations of the disorder. A survey of psychiatrically hospitalized children and adolescents was conducted. 3.2% of the sample of boys was found to have PDD. Underappreciation of the presence of PDD characterized the patients. Family members experienced a wide array of psychiatric symptoms and showed evidence for the presence of familial Tourette syndrome.