Dementia as a major comorbidity in late-onset epilepsy

Epilepsy is more common in the elderly population, with a higher prevalence of epilepsy-related neurological diseases, such as stroke and traumatic brain injury. Although dementia is also known to be a potential cause of epilepsy in the elderly, estimating its accurate contribution is challenging because of its high prevalence in the general elderly population. To characterize the clinical features of patients with comorbid dementia, we compared the characteristics of these patients with those of elderly patients with post-stroke epilepsy and an unidentified etiology. Of the 494 patients who were first diagnosed with epilepsy after the age of 65 years, 194 were classified as having post-stroke epilepsy, 105 as having comorbid dementia, and 71 as having epilepsy of unidentified etiology. Patients with comorbid dementia were older at seizure onset (p < .001) and at the last treatment (p < .001) than those in the other groups. They were more likely to have depression (p = .04) and were more frequently treated with acetylcholine esterase inhibitors and memantine before the diagnosis of epilepsy (p < .001). In contrast, stroke-related risk factors, such as hypertension (p < .001) and dyslipidemia (p = .01), were more prevalent in patients with post-stroke epilepsy. Considering that stroke itself is a well-recognized risk factor for dementia and epilepsy in the elderly, our study suggests that dementia may be a major comorbidity and a risk factor for late-onset epilepsy.