Increased risk for current and former smokers, and those who started smoking at an earlier age
Thursday, February 17, 2011 (Last Updated: 02/18/2011)
THURSDAY, Feb. 17 (HealthDay News) -- Cigarette smoking is associated with an increased risk of amyotrophic lateral sclerosis (ALS), with an increased risk for those who started smoking at a younger age, according to a study published in the February issue of Archives of Neurology.
Hao Wang, M.D., Ph.D., from the Harvard School of Public Health in Boston, and colleagues examined the association between smoking and ALS in five large cohorts. Death from ALS was identified using the National Death Index, and, in two of the cohorts, non-fatal ALS was also included.
The investigators identified 832 cases of ALS in the cohorts. There was an increased risk of ALS in smokers compared to those who had never smoked; the relative risk after adjusting for age and sex was 1.44 for former smokers and 1.42 for current smokers. The risk of ALS was associated with pack-years smoked, smoking duration, and number of cigarettes smoked per day only when those who had never smoked were included in the analysis. Among those who had smoked, those who started smoking at a younger age had an increased risk of ALS.
"Among smokers, the risk of ALS increased with decreasing age at smoking initiation but was unrelated to smoking duration or intensity. Better understanding of the relation between smoking and ALS may further the discovery of other risk factors and help elucidate the nature of the disease," the authors write.
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