The Impact of Alcohol and Hypertension on Stroke Incidence in a General Japanese Population

Background and Purpose The relationship between alcohol intake and stroke has been inconsistent in previous studies. We examined the separate and combined effects of drinking habits and hypertension on stroke incidence in a prospective survey of a general Japanese population. Methods A total of 1621 stroke-free Hisayama residents aged 40 years or older were classified by their alcohol intake into nondrinkers, light drinkers (<34 g of ethanol per day), and heavy drinkers (≥34 g of ethanol per day) and followed up prospectively for 26 years from 1961. Results During the follow-up period, cerebral infarction developed in 244 subjects and cerebral hemorrhage in 60. For men, the incidence of cerebral hemorrhage increased significantly with rising alcohol consumption. In contrast, the incidence of cerebral infarction was slightly lower in light drinkers than in nondrinkers, while it increased significantly in heavy drinkers compared with light drinkers. Female drinkers had a lower incidence of cerebral infarction but a slightly higher incidence of cerebral hemorrhage than nondrinkers, as did male light drinkers. Among the hypertensive subjects, the age- and sex-adjusted relative risk of cerebral hemorrhage was significantly elevated in heavy drinkers versus abstainers (3.13; 95% confidence interval [CI], 1.08 to 9.10), but the increase was not significant for light drinkers. In contrast, the relative risk did not significantly increase for normotensive light and heavy drinkers. Compared with hypertensive light drinkers, the relative risk of cerebral infarction significantly increased in hypertensive heavy drinkers (1.96; 95% CI, 1.08 to 3.57) but remained unchanged in normotensive heavy drinkers. Significant associations between alcohol intake and stroke were substantially the same even after controlling for other risk factors in multivariate analysis. Conclusions Among hypertensive individuals, heavy alcohol consumption leads to a significant increase in the risk of cerebral hemorrhage, suggesting a synergistic effect of alcohol and hypertension, while light alcohol consumption significantly reduces the risk of cerebral infarction.