The prevalence of psychiatric disorders among people with intellectual disabilities: An analysis of the literature

Background It has often been stated that the prevalence of psychiatric disorders in people with intellectual disabilities is greater than it is in the population as a whole. Method The epidemiological studies on psychiatric disorders in people with intellectual disabilities were reviewed. Results There is evidence that the prevalence of psychiatric disorder is greater in children with intellectual disabilities, compared with children with normal IQs, that it is higher in both adults and children with severe intellectual disabilities compared with people with mild or no intellectual disability and that the rate of problematic behaviour is higher in both adults and children having intellectual disabilities, than in their non-disabled peers. Conclusions There is no sound evidence that the prevalence of psychiatric disorders in adults with mild intellectual disability is greater than in the population as a whole.