Mental disorder in adults with mental retardation and epilepsy

The controversy regarding the exact nature of the relationship between psychopathology and epilepsy continues. We studied the rate of mental disorder in 150 adults with mental retardation and epilepsy among the residents of a health district of the United Kingdom who lived either in institutions or in the community, and compared them with an age-, sex-, and IQ-matched nonepileptic adult mentally retarded population from the same institution and community. Mental disorder was assessed under three headings, namely severe maladaptive behavior, psychiatric illness according to ICD-9 criteria, and personality disorder. Sixty-five percent of the whole cohort had a diagnosis of mental disorder, and 55% showed severe maladaptive behavior. No significant difference in the rate of mental disorder emerged between the epileptic and nonepileptic groups, although the institutionalized subjects as opposed to the community-based subjects and severely mentally retarded adults compared with the mild to moderately mentally retarded adults showed a significantly higher rate of mental disorder in general and severe maladaptive behavior in particular. We hypothesized that underlying brain damage rather than epilepsy per se is a stronger determinant of psychopathology in the studied patient group.