Seizures in Patients with Alzheimer’s Disease or Vascular Dementia

In the early view access of Epilepsia from December 6, 2012, Drs. Imfeld and colleagues from the Division of Clinical Pharmacy and Epidemiology and the University Hospital in Basel, Switzerland and the Boston Collaborative Drug Surveillance Program present an important study assessing risk factors for developing seizures in association with Alzheimer’s or vascular dementia. Although several previous studies have shown that Alzheimer’s increases the risk for developing epilepsy, very little is known as to which factors in patients with dementia leads to seizures and epilepsy and what happens to these individuals.

To answer that question, researchers utilizing the United Kingdom-based General Practice Research Database identified patients over the age of 65 years with a diagnosis of either vascular dementia or Alzheimer’s disease between the years 1998 and 2008 and a matched comparison group of patients who did not have dementia. Utilizing specialized statistical techniques, they estimated an odds ratio of developing seizures in patients with Alzheimer’s and vascular dementia looking at age of onset and the duration of dementia as well as the use of anti-dementia drugs.

7,086 cases with Alzheimer’s disease, 4,438 with vascular dementia (Total n=11,524) were matched to dementia-free patients. Of these, 180 cases with an incident diagnosis of epilepsy were found. The incident rate of seizures for patients with Alzheimer’s disease and vascular dementia was 5.6 per 1,000 person years and 7.5 per 1,000 person years respectively; and it was 0.8 in the dementia free group. They also noted that patients with longer standing Alzheimer’s disease, more than three years, had a higher risk of developing seizures and epilepsy than those with a shorter disease duration whereas patients with vascular dementia, the opposite was observed. The authors concluded that seizures and epilepsy are substantially more common in patients with Alzheimer’s disease and vascular dementia than in patients who do not have dementia. The role of disease duration as a risk factor for seizures and epilepsy seems to differ between Alzheimer’s disease and vascular dementia.

This study helps to delineate the unique aspects of Alzheimer’s disease especially in terms of its increased risk for seizures as compared to other dementias which may have a different mechanism by which the risk factor for epilepsy may occur. Obviously, more work is needed in this area to understand why there is an increased risk of epilepsy associated with two of the most common forms of dementia – Alzheimer’s disease and vascular dementia.