Psychiatric disorders in persons with Down syndrome.

This study was designed to provide information on the prevalence and nature of psychiatric disorders in 497 individuals with Down syndrome. There were 261 patients under 20 years of age and 164 patients 20 years and older, with both groups followed as outpatients, and 72 residents from a state school. The overall frequency of psychiatric disorders in our study population was 22.1%. Patients under 20 years of age often displayed disruptive behaviors, anxiety disorders, and repetitive behaviors. Individuals with Down syndrome 20 years and older who were followed as outpatients more often exhibited major depressive disorders and state school residents were found to have an increased prevalence of dementia.