Incident Epilepsy Risk among the Elderly

February 6, 2017
Veronica Hackethal, MD

Stroke is the most common cause of epilepsy in older adults, but there is limited information about rates and risk factors in this population.

Among older adults, black race, advanced age, and a history of stroke are associated with incident epilepsy, according to results from the Cardiovascular Health Study (CHS) published online in Neurology.1

Importantly, the study found that older blacks have about four times increased risk of incident epilepsy, compared to nonblacks.

“[W]e found that epilepsy in older adults was common, prevalent in 3.7% of individuals at baseline and affecting 5.7% of the cohort by the end of 14 years of follow-up… We confirmed that independent predictors of developing epilepsy after age 65 included advanced age, black race, and history of both prevalent and incident stroke,” wrote first author Hyunmi Choi, MD, MSc, of Columbia University (New York, NY), and colleagues.

Epilepsy is common among older adults. Though stroke is the most common cause of epilepsy in older adults, limited information exists about rates and risk factors in this population.

The study drew data from the CHS, a large population-based cohort study of 5888 older adults (42% men, 84% white) in North Carolina, California, Maryland, and Pennsylvania. To identify epilepsy cases, researchers merged data from the CHS with outpatient Medicare claims data. Information came from self-report data, receipt of antiepileptic medication according to Center for Medicaid Services claims, as well as hospitalization or outpatient ICD-9 codes. At enrollment, 3.7% of participants had epilepsy. 

Key results at 14 years of follow-up:

• 120 people were diagnosed with epilepsy

♦ Period prevalence: 5.7% over the entire study period

• Risk of incident epilepsy significantly higher among:

♦ Blacks vs nonblacks (HR 4.04, 95% CI 1.99–8.17)

♦ Participants aged 75-79 years vs 65-69 years (HR 2.07, 95% CI 1.21–3.55)

♦ Participants with history of stroke vs no stroke (HR 3.49, 95% CI 1.37–8.88)

♦ Multivariable analyses controlled for sex, race, marital status, education, occupation, body mass index, health status, and comorbidities

• Black race (HR 3.61, 95% CI 1.61–8.11) and incident stroke (HR 2.94, 95% CI 1.71– 5.06) were independently linked to incident epilepsy

• Risk of incident epilepsy was significantly lower with coronary heart disease (HR 0.26, 95% CI 0.08–0.85) and obesity (HR 0.2, 95% CI 0.04–0.95)

“Disparity in risk by race was the most salient finding in our study. Blacks had a greater likelihood of having prevalent epilepsy and increased risk of developing incident epilepsy after age 65,” the authors wrote.

Disparity in stroke risk may be involved, according to the authors. Blacks have more than twofold increased risk of stroke compared to whites, according to past studies cited by the authors. However, findings also suggested that black race was linked to increased risk of epilepsy, independent of stroke.  The authors provided several alternative explanations, including genetic causes. Though genetic epilepsy is unlikely to start in older age, some genetic mutations may increase susceptibility to epilepsy, they pointed out.

Blacks also have higher risk for other disorders which in turn increase the risk of epilepsy, such as Alzheimer disease. However, the study could not evaluate other risk factors for epilepsy, like brain tumor, traumatic brain injury, dementia, or psychiatric illness.

“Additional study is needed to determine neurologic or medical conditions raising the risk of epilepsy among older adults and to identify mechanisms by which race affects this risk,” the authors concluded.

Take-home Points

• A population-based cohort study confirmed incident epilepsy is common in older adults.

• Blacks had about four times increased risk of incident epilepsy.

• Participants of advanced aged (75-79 years) had double the risk of incident epilepsy, compared to 65- to 69-year-olds.

• History of stroke was linked to 3.5 times increased risk of incident epilepsy, compared to no stroke.

• Black race and incident stroke were independently linked to incident epilepsy.

• More research is needed to identify comorbidities that increase epilepsy risk in older adults, and how race affects risk.

The study was supported by the National Heart, Lung and Blood Institute and the National Institute of Neurological Diseases and Stroke.

One or more authors reports research support, royalties, consulting, board membership, and/or other compensation from one or more of the following: UCB-Pharma, Lundbeck, Eisai, Sunovion, UpToDate, Biotelemetry/Cardionet, BMS-Pfizer Partnership, Boehringer-Ingelheim, Sanofi-Regeneron, BMS-Sanofi (Plavix), Merck/Organon (Nuvaring), Hi-Tech Pharmaceuticals, National, Founders Affiliate and New York City chapter boards of the American Heart Association/American Stroke Association, and/or NIH.

Reference: Choi H, et al. Predictors of incident epilepsy in older adults: the Cardiovascular Health Study. Neurology. 2017 Jan 27.