Epilepsy in individuals with a history of Asperger's syndrome: a Danish nationwide register-based cohort study.

We performed a nationwide, register-based retrospective follow-up study of epilepsy in all people who were born between January 1, 1980 and June 29, 2006 and registered in the Danish Psychiatric Central Register with Asperger's syndrome on February 7, 2011. All 4,180 identified cases with AS (3,431 males and 749 females) were screened through the nationwide Danish National Hospital Register (DNHR) with respect to epilepsy. Mean age at follow-up was 18.1 years (range 4-31 years). Of the 4,180 individuals with AS, 164 (3.9%) were registered with at least one epilepsy diagnosis in the DNHR, which is significantly increased (p < 0.0001) relative to the same age group in the general population, where an estimate is about 2.0%.