Mental retardation and psychiatric illness.

Although traditional diagnostic criteria are accepted for use with mentally retarded persons, diagnosis of psychiatric disorders in this population is often complicated by clinicians' ignoring or underestimating such disorders and by patients' communication problems. The revision of DSM-III and changes in policies of third-party payers have sensitized clinicians to the presence of psychopathology among mentally retarded persons. The authors discuss the relationship between mental illness and mental retardation and review recent research on the diagnosis of specific psychiatric disorders in these patients. Some problems, such as behavioral disruptiveness, psychoses, and phobias, are more prevalent among mentally retarded persons than among other populations, whereas other problems, such as alcoholism and suicide, may be less common.