A Prevalence Study of Pervasive Developmental Disorders in North Dakota

To determine prevalence rates for the pervasive developmental disorders (PDD) in North Dakota, all relevant health and service providers were asked to provide names and records of all patients who had autistic symptoms. All identified patients were seen by the authors for a comprehensive evaluation. Of North Dakota's 180,986 children, ages 2 through 18, 21 met DSM-III criteria for infantile autism (IA), two met criteria for childhood onset pervasive developmental disorder (COPDD), and 36 were diagnosed as having atypical pervasive developmental disorder (APDD) because they met behavioral criteria for COPDD before age 30 months but never met criteria for IA. The prevalence rates were estimated at 1.16 per 10,000 for IA, 0.11 per 10,000 for COPDD, and 1.99 per 10,000 for APDD. The combined rate for all PDD was 3.26 per 10,000 with a male to female ratio of 2.7 to 1. Results are discussed in relation to previous prevalence studies using other diagnostic criteria.