Alcohol and the Risk of Ischemic and Hemorrhagic Stroke

Alcohol consumption has been linked to increased risk of hemorrhagic stroke and decreased risk of ischemic stroke. This study examined these associations in 19,544 Japanese men, aged 40–59 years, who were followed for 11 years. Results from analyses adjusted for potential confounders (e.g., age, smoking, diabetes, hypertension) include the following:

• Of 694 incident strokes, approximately one half were hemorrhagic (compared with <20% in the United States).
• Compared with occasional drinking (1–3 days per month), consuming up to about 12 drinks (<150 g of alcohol) per week was associated with a significant decrease in risk (41%) of ischemic stroke, a borderline significant increase in risk (73%) of hemorrhagic stroke, and no excess risk of total stroke.
• Those who consumed greater amounts of alcohol experienced significant increases in risk of hemorrhagic stroke (approximately 2-fold) at all drinking levels, but no significant differences in risk of ischemic stroke.

Comments:

This study confirms findings from previous research—moderate alcohol consumption reduces risk of ischemic stroke. However, it found an increased risk of hemorrhagic stroke at amounts lower than previously reported in the United States (where increases are usually seen at >3–5 drinks per day). Because the greater prevalence of hemorrhagic stroke in Asia has a number of possible etiologies, it is unclear whether alcohol's impact on stroke will be the same in the United States as in Japan. Nonetheless, this study challenges the belief that only heavy drinking increases the risk of hemorrhagic stroke.

R. Curtis Ellison, MD

Reference:

Iso H, Baba S, Mannami T, et al. Alcohol consumption and risk of stroke among middle-aged men: the JPHC Study Cohort I.Stroke. 2004;35(5):1124–1129.
(view abstract)