PREVALENCE AND ASSOCIATED FEATURES OF EPILEPSY IN ADULTS WITH DOWNS-SYNDROME

The aim of this study was to establish the prevalence of epilepsy in p ersons with Down's syndrome aged 19 years and over. A total of 191 adu lts with Down's syndrome were identified, giving a prevalence of 0.76/ 1000 (95% Cl 0.75 to 0.77). Of these, 18 had epilepsy, giving a preval ence of 9.4% (95% Cl 5.3% to 13.5%). The prevalence of epilepsy increa sed with age, reaching 46% in those over 50. The neurophysiological (E EG) findings of the epilepsy group were compared with those of a contr ol group of Down's syndrome adults without epilepsy. Paroxysmal abnorm alities consistent with a diagnosis of epilepsy were found in 80% of t he epilepsy group, compared with only 13% of controls (P<0.001). Epile psy of late onset was associated with diffuse EEG abnormalities and cl inical evidence of dementia. The age distribution and EEG findings sug gest two independent processes in the causation of epilepsy: late-onse t epilepsy associated with clinical evidence of dementia, and early-on set epilepsy in the absence of dementia.