Alcohol and stroke: a community case-control study in Asturias, Spain.

The relationship between alcohol consumption and stroke is uncertain. Heavy alcohol consumption has been associated with an increased risk of stroke, while light drinking appears to be protective. However, the evidence is not uniform. We sought to examine the relationship between alcohol consumption and stroke, according to stroke type. We performed a population-based case-control study from September 1990 to December 1991. The study comprised 467 incident cases of stroke and 477 controls aged between 40 and 85. Case was defined following WHO criteria and control was randomly selected from the study base population. Alcohol exposure was obtained by medical interview. We found that consumption of less than 30 g/day of alcohol was protective against all stroke types combined, the multivariated adjusted odds ratio (OR) was 0.58 (95% confidence interval [CI], 0.41-0.83). Moderate alcohol drinking is also protective against all cerebral infarction combined (OR = 0.53; 95% CI, 0.35-0.80) and cortical infarction (OR = 0.40; 95% CI, 0.18-0.86). Drinking up to 30 g/day of alcohol has a borderline protective effect on deep cerebral infarction (OR = 0.40; 95% CI, 0.16-1.02) and has no effect on intracerebral hemorrhage (OR = 0.88; 95% CI, 0.44-1.74). Heavy alcohol drinking, over 140 g/day, is a risk factor for all stroke types combined (OR = 3.2; 95% CI, 1.1-9.7), all cerebral infarction combined (OR = 5.0; 95% CI, 1.5-16.3), small deep cerebral infarction (OR = 9.7; 95% CI, 2.6-36.7), intracerebral hemorrhage (OR = 6.2; 95% CI, 1.3-24.0), and is marginally associated with superficial cerebral infarction (OR = 4.6; 95% CI, 1.0-20.6). The relationship between alcohol and stroke depends on the alcohol dose and the pathology of the disease. Atherosclerosis of the large and medium cerebral arteries is found mainly in superficial cerebral infarction, and this type of stroke shows a J-shaped relationship with alcohol similar to that found in coronary heart disease, suggesting that they are similar diseases. On the other hand, arteriosclerosis of the penetrating arteries has been found in deep cerebral infarction and intracerebral hemorrhage, while atherosclerosis is not prominent. This may explain why alcohol does not have a protective effect on cerebral hemorrhage whereas heavy drinking is a strong risk factor in these two types of stroke.