Seizures in Alzheimer Disease

Abstract

Background: Transient symptoms in Alzheimer dis- ease (AD) are frequent and include seizures, syncope, and episodes of inattention or confusion. The incidence of seizures inADand predictors of which patients withAD might be more predisposed to them is based primarily on retrospective studies and is not well established. Objective: To determine the incidence and predictors of new-onset unprovoked seizures. Design: Prospective cohort study. Setting: Three academic centers. Patients: Four hundred fifty-three patients with prob- ableADobserved prospectively from mild disease stages since 1992. Main Outcome Measure: Informant interviews ev- ery 6 months included questions about whether the pa- tient had a seizure (convulsion, fainting, or “funny” spell) and whether diagnosis or treatment for epilepsy or sei- zure was made. Two epileptologists independently ret- rospectively reviewed all available medical records for 52 patients with positive responses to either of these ques- tions, and using a specific checklist form, events were di- agnosed as to whether they were unprovoked seizures Author Affiliations are listed at the end of this article. zures are common in various brain dis- eases; however, differentiation between nonepileptic and epileptic events may be challenging. Patients with dementia may experience nonepileptic episodes of inat- tention or confusion as well as syncope or near-syncope and seizures. Hospitaliza- tionsmayensue, and anticonvulsant agents are often prescribed. The relationship of epileptic activity to AD is of clinical im- portance. In addition, it has been pro- posed to relate to the pathogenesis of AD. B (intrarater concordance, =0.67). Diagnosis of unpro- voked seizures constituted the event in survival analy- ses. Potential predictors included sex, age, race/ ethnicity, educational achievement, duration of illness, baseline cognition and function, depression, medical co- morbidities, and time-dependent use of cholinesterase in- hibitors and neuroleptic agents, apolipoprotein E geno- type, and previous electroencephalographic findings. Results: Over the course of 3518 visit-assessments (per patient: mean, 7.8; maximum, 27), 7 patients (1.5%) de- veloped seizures. Younger age was associated with higher risk (hazard ratio, 1.23; 95% confidence interval, 1.08- 1.41; P=.003 for each additional year of age) of seizure incidence. No other predictor was significant. The over- all incidence of seizures was low (418 per 100 000 person- years of observation) although significantly higher than expected for idiopathic unprovoked seizures in similar age ranges of the general population (hazard ratio, 8.06; 95% confidence interval, 3.23-16.61). Conclusions: Unprovoked seizures are uncommon in AD, but they do occur more frequently than in the gen- eral population. Younger age is a risk factor for seizures in AD.