A prospective case control study of psychiatric disorders in adults with epilepsy and intellectual disability

Purpose: No study to date has prospectively investigated the impact of epilepsy on psychiatric disorders among adults with an intellectual disability (ID). This study aimed to determine prospectively the influence of epilepsy on the development of psychiatric disorders in adults with ID. Method: Psychiatric symptoms were measured prospectively over a 1‐year period among 45 adults with ID and active epilepsy and 45 adults with ID without epilepsy, matched on level of ID. The 1‐year incidence rate (IR) of commonly occurring Axis 1 psychiatric disorders was compared with and without controlling for possible confounding factors. Total psychiatric symptom scores over the period were compared between the two groups using repeated‐measures analysis of covariance. Key Findings: Adults with epilepsy and ID had a more than seven times increased risk for developing psychiatric disorders, particularly depression and unspecified disorders of presumed organic origin, including dementia, over a 1‐year period compared to those with ID only. Comparison of the psychiatric scores showed the epilepsy group to have significantly higher unspecified disorder and depression symptom scores. Significance: The findings point to an increased risk of depression and unspecified disorders, including dementia, among adults with ID and epilepsy. Further exploration of the nature and treatment of these unspecified disorders may help the care of people with epilepsy and ID.