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)