Seizures in patients with Alzheimer's disease or vascular dementia: A population-based nested casecontrol analysis

Purpose: Patients with Alzheimer's disease (AD) have an increased risk of developing seizures or epilepsy. Little is known about the role of risk factors and about the risk of developing seizures/epilepsy in patients with vascular dementia (VD). The aim of this study was to assess incidence rates (IRs) of seizures/epilepsy in patients with AD, VD, or without dementia, and to identify potential risk factors of seizures or epilepsy. Methods: We conducted a follow-up study with a nested casecontrol analysis using the United Kingdombased General Practice Research Database (GPRD). We identified patients aged 65years with an incident diagnosis of AD or VD between 1998 and 2008 and a matched comparison group of dementia-free patients. Conditional logistic regression was used to estimate the odds ratio (OR) with a 95% confidence interval (CI) of developing seizures/epilepsy in patients with AD or VD, stratified by age at onset and duration of dementia as well as by use of antidementia drugs. Key Findings: Among 7,086 cases with AD, 4,438 with VD, and 11,524 matched dementia-free patients, we identified 180 cases with an incident diagnosis of seizures/epilepsy. The IRs of epilepsy/seizures for patients with AD or VD were 5.6/1,000person-years (py) (95% CI 4.66.9) and 7.5/1,000py (95% CI 5.79.7), respectively, and 0.8/1,000py (95% CI 0.61.1) in the dementia-free group. In the nested casecontrol analysis, patients with longer standing (3years) AD had a slightly higher risk of developing seizures or epilepsy than those with a shorter disease duration, whereas in patients with VD the contrary was observed. Significance: Seizures or epilepsy were substantially more common in patients with AD and VD than in dementia-free patients. The role of disease duration as a risk factor for seizures/epilepsy seems to differ between AD and VD.