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© 2008 American Academy of Neurology Population-based prospective study of cigarette smoking and risk of incident essential tremorFrom the G.H. Sergievsky Center, Department of Neurology, and Taub Institute for Research on Alzheimer’s Disease and the Aging Brain, College of Physicians and Surgeons, Columbia University, and Mailman School of Public Health, Columbia University (E.D.L.), New York, NY; and Department of Neurology (J.B.-L., F.B.-P.), University Hospital "12 de Octubre," Madrid, Spain. Other members of the NEDICES Study Group are listed in the acknowledgment. Address correspondence and reprint requests to Dr. Elan D. Louis, Unit 198, Neurological Institute, 710 West 168th Street, New York, NY 10032 EDL2{at}columbia.edu Background: Smoking cigarettes is associated with lower risk of Parkinson disease (PD). Despite the clinical links between PD and essential tremor (ET), there are few data on smoking in ET. One study showed an association between smoking and lower ET prevalence. We now study whether baseline smoking is associated with lower risk of incident ET. Methods: Using a population-based, cohort design, baseline cigarette smoking habits were assessed in 3,348 participants in an epidemiologic study in Spain, among whom 77 developed incident ET. Results: There were 3,348 participants, among whom 397 (11.9%) were smokers at baseline. Five (6.5%) of 77 incident ET cases had been smokers at baseline, compared with 392 (12.0%) of 3,271 controls (p = 0.14). Baseline pack-years were lower in incident ET cases than in controls (9.2 ± 17.7 vs 15.7 ± 28.4, p = 0.002). Participants were stratified into baseline pack-year tertiles, and few incident ET cases were in the highest tertile (4 [5.2%] cases vs 431 [13.2%] controls, p = 0.039). In Cox proportional hazards models, the highest baseline pack-year tertile was associated with lower risk of incident ET; those in the highest pack-year tertile were one-third as likely to develop ET when compared with nonsmokers (relative risk [RR] 0.37, 95% CI 0.14–1.03, p = 0.057 [unadjusted model] and RR 0.29, 95% CI 0.09–0.90, p = 0.03 [adjusted model]). Conclusions: We demonstrated an association between baseline heavy cigarette smoking and lower risk of incident essential tremor. The biologic basis for this association requires future investigation.
Abbreviations: ET = essential tremor; MPTP = 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine; NEDICES = Neurological Disorders in Central Spain; OR = odds ratio; PD = Parkinson disease; RR = relative risk; UPDRS = Unified Parkinson’s Disease Rating Scale.
NEDICES was supported by the Spanish Health Research Agency and the Spanish Office of Science and Technology. E.D.L. is supported by R01 NS042859, R01 NS039422, and ES P03 09089 from the NIH, Bethesda, MD. Disclosure: The authors report no conflicts of interest. Received October 24, 2007. Accepted in final form February 1, 2008. This article has been cited by other articles:
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