Early epileptic seizures after stroke are associated with increased risk of new-onset dementia

Abstract

Background: Subclinical vascular or degenerative lesions occur in the brain before the clinical expression of dementia. Those lesions in a brain that just experienced a stroke may have lower thresholds for early epileptic seizures. Therefore, epileptic seizures may be a marker of subclinical brain lesions, which may lead to dementia. Objective: To test the hypothesis that patients with stroke who have epileptic seizures without dementia have an increased risk of new-onset dementia. Methods: 169 consecutive patients with stroke without pre-existing dementia recruited in the Lille Stroke/Dementia Study were investigated (90 men; 150 ischaemic strokes; median age 73 years). Pre-stroke cognitive functions were evaluated with the Informant Questionnaire on Cognitive Decline in the Elderly (IQCODE), with a cut-off of 104 for the diagnosis of dementia. The patients were followed up over a 3-year period. Dementia was diagnosed with International Classification of Diseases, 10th revision criteria in survivors who underwent neurological visits, and with the IQCODE score in those who could not. The relationship between epileptic seizures and new-onset dementia was studied within 3 years, using life-table methods. Results: 9 patients (5.3%; 95% CI 2.9 to 8.7%) had early seizures. Epileptic seizures were independent predictors of new-onset dementia within 3 years after stroke (HR 3.81; 95% CI 1.13 to 12.82), with increasing age (HR 1.04; 95% CI 1.01 to 1.08), IQCODE scores at admission (HR 1.08; 95% CI 1.02 to 1.13) and diabetes mellitus (HR 3.52; 95% CI 1.46 to 8.47). Conclusion: Patients with stroke who have epileptic seizures may be at increased risk of dementia. Whether cognitive follow-up should be systematically performed in those patients remains to be validated.