Abstracts

Nicotine has been shown to cause convulsions at high doses. No prospective studies have directly related smoking to development of seizures or epilepsy, though it is a strong risk factor for stroke, which is a cause of late onset seizures/epilepsy. We investigated the relation between smoking and incidence of seizures/epilepsy among women prospectively followed in the Nurses[apos] Health Study II (NHSII). NHSII participants have been followed since 1989 with biennial questionnaires requesting lifestyle and health information. In 2001, participants were asked about occurrence and dates of seizures/epilepsy. For confirmation and classification of self-reports, we administered supplementary questionnaries to women reporting incident seizures/epilepsy occurring from 1995 to 2001. We compared rates of seizures/epilepsy across categories of smoking (never, past, current) among 70,000+ women, aged 30-52. We adjusted rates for age and other potential confounders such as alcohol, caffeine, diabetes, hypertension or high cholesterol using Cox proportional hazards models. In alternate analyses, rates were adjusted for stroke. From 1995 through 2001, during 413,497 person-years of follow-up, we identified 73 incident cases of seizures/epilepsy; the most frequent type was symptomatic partial epilepsy (37%). Preliminary medical record validation of self-reports confirmed epilepsy diagnosis. Compared to never smokers, age-adjusted relative risk (RR) of seizures/epilepsy for past smokers was 0.80 (95% CI= 0.42, 1.50) and for current smokers, 2.24 (95% CI= 1.22, 4.11); in multivariate analyses, for current smokers, the RR was 2.11 (95% CI= 1.13, 3.95). With further adjustment for strokes, we observed some attentuation in RR for current smokers: RR=1.77 (95% CI=0.91, 3.42). Trends were not detected with increasing smoking dose (p=0.22). In this population-based study, we found that cigarette smoking increases risk of seizures or epilepsy with a trend toward a relationship independent of stroke.
[table1] (Supported by CA50385, the main Nurses[apos] Health Study II grant.)