Epilepsy and antiepileptic drug use in elderly people as risk factors for dementia

To assess the role of epilepsy and antiepileptic drugs (AEDs) as risk factors for probable Alzheimer's disease (AD) and for all dementias in the Canadian Study of Health and Aging (CSHA). A secondary objective was to isolate the effect of the AED phenytoin on the development of dementia and AD.

The cohort consists of 5376 participants aged 65 years or older with no evidence of dementia, defined as Modified Mini-Mental State (3MS) score > or =78. Primary exposure was self-report or clinical diagnosis of epilepsy at baseline (n=39), or self-report of AED therapy (n=67). Primary outcomes were development of dementia, defined as 3MS<78, or AD, determined by clinical examination using standard criteria, during a 5-year follow-up period. People whose 3MS score remained > or =78 served as the comparison group.

People reporting AED use at baseline had an age, sex and baseline 3MS adjusted odds ratio (OR) of 2.11 (95% CI 1.11 to 4.01) for developing dementia compared to those not taking AEDs at baseline. The association remained significant using only phenytoin as the exposure. No significant association was found between AED use and development of AD, nor between epilepsy and development of either AD or dementia.

Older adults taking AEDs are at a significantly higher relative risk of developing dementia than those not taking AEDs. Further investigation of this finding is warranted.