Seizures and epilepsy in a mentally retarded population over the first 22 years of life

The paper examines seizure histories in a 5-year cohort, age 22, who had been classified as mentally retarded during the school years in a British city. Results are examined in relation to matched comparisons, a borderline mentally retarded group, and other studies. Twenty-seven percent of the mentally retarded experienced one or more seizures. Equivalent figures for the borderline and comparison groups are 11% and 4% respectively. Within the mentally retarded population, the more severely mentally retarded more often had seizures, had them earlier and over a longer time span than the mildly retarded. Seizures are described on a year-by-year basis using both longitudinal and cross-sectional views. Prevalence studies of epilepsy in mentally retarded populations are reviewed, and problems of definition and method are discussed.