Psychiatric practice for intellectual disability in the USA: challenges and advances.

Individuals with intellectual disability are thought to make up at least 1% of the population, and it is estimated that approximately one-third of them have a comorbid psychiatric disorder (Harris, 2006). These 'dually diagnosed' individuals present a particular diagnostic and therapeutic challenge. A difficulty facing psychiatry in the USA over the past several decades has been to interest and educate a sufficient number of psychiatrists to meet the mental health needs of this group of patients (Department of Health and Human Services, 2002).