Page last updated: Tuesday, May 13, 2008
Alcohol and stroke
by Elizabeth Holmgren
Stroke is one of the leading causes of death and disability in the developed world. Because full recovery of speech, thought and motor function is uncertain, prevention is of utmost importance.

While heavy alcohol consumption appears to increase risk of all types of strokes, scientists have begun to acknowledge the potentially protective effect of moderate alcohol consumption. Recent months have seen the publication of many new studies. Results have been consistent enough for at least one organization, the National Stroke Association (NSA), to include some favorable information about alcohol and stroke in its prevention guidelines.

One of the difficulties in advising about alcohol and stroke is that different types of stroke have slightly different relationships with alcohol intake. While the evidence on moderate intake and the most common form of stroke, ischemic stroke, has been almost entirely favorable, some studies have found an increased risk for the less common hemorrhagic stroke.

In a "Multidisciplinary Consensus Statement" from the NSA published this year in JAMA, researchers describe some of these differences, noting that "there is evidence that light to moderate drinking may have beneficial effects by increasing high-density lipoprotein cholesterol levels and decreasing platelet aggregation and fibrinogen levels. They advise, "Since some ingestion of alcohol, perhaps up to 2 drinks per day, may actually help reduce the risk of stroke, drinking in moderation should be recommended for those who drink alcohol and have no health contraindications to alcohol use. However, those who do not customarily drink should not be encouraged to do so."

In 1998, NSA’s Prevention Advisory Board stated, "Studies now show that drinking up to two drinks per day can reduce your risk for stroke by about half. More alcohol than this each day can increase your risk for stroke by as much as three times and also can lead to liver disease, accidents and more... if you don’t drink, don’t start!" The acknowledgment of recent scientific developments by organizations such as the NSA reflect considerable changes in public health attitudes toward alcohol.

In the past year, new studies from Spain, Australia, United States and Denmark have reported a favorable association between low-to-moderate drinking and a reduced risk of stroke. In the Journal of Clinical Epidemiology,Spanish re-searchers investigated the relationship between alcohol consumption and stroke in a case-control study. They found a J-shaped relation between alcohol and all stroke combined, writing, "We found that consumption of less than 30 g/day of alcohol was protective against all stroke types combined." Specifically moderate intake was most protective against cerebral infarction and cortical infarction, and heavy consumption of over 140 g/day increased risk of all types of stroke.

Despite past evidence that has been contradictory, the Spanish researchers found no increased risk for hemorrhagic stroke among moderate drinkers. Interestingly, an Australian study published this year in Epidemiology investigated hemorrhagic stroke directly, with researchers analyzing the relation between levels of all alcohol types and risk of intracerebral hemorrhage (ICH), stroke caused by bleeding in the brain. When compared to non-drinkers, moderate drinkers of all alcohol beverages had a 40 percent reduction in risk of ICH, though heavy drinkers had a substantial increase in risk. The researchers noted a 70 per-cent reduction for male wine drinkers and a 50 percent reduction for female wine drinkers, as compared to "never drinkers."

In a well-publicized study by Sacco et al published in JAMA in 1999, light or occasional alcohol consumption was associated with lowered ischemic stroke (responsible for 80 percent of all strokes) risk by up to 62 percent compared to non-drinkers in a multi-ethnic New York City population. For people who consumed up to two alcoholic drinks per day, stroke risk was 45 percent lower compared to non-drinkers. But people who had at least five drinks daily tripled their stroke risk.

Finally, Danish researchers reported a U-shaped relation between alcohol intake and risk of stroke, based on the Copenhagen City Heart Study. "In analyses adjusted for age, sex, and smoking," wrote Truelsen, M.D.et al in Epidemiology, "intake of wine on a monthly, weekly, or daily basis was associated with a lower risk of stroke compared with no wine intake." Furthermore, the relation could be explained as a linear relationship, indicating a dose-response effect.

Conclusion

These four studies, all published in 1999, contribute to the evidence demonstrating a protective effect for moderate consumption on the risk of stroke, particularly for ischemic stroke. Never the less, contra-dictory results, particularly in the area of hemorrhagic stroke, continue, as a recent Scottish study published in the British Medical Journal showed:These researchers found a clear increased risk of stroke mortality for heavier drinkers (over 22 units–nearly four bottles of wine–per week), but did not find a protective effect at lower levels of consumption.

Although some controversy in this area of study will inevitably remain for some time, it can safely be said that the balance of studies now point to a favorable asso-ciation between moderate alcohol consumption and reduced risk of stroke. As the New York researchers explained in their JAMA article, "While no study has shown benefit in recommending alcohol consumption to those who do not drink, our data support the view, endorsed by the NAS in its Stroke Prevention Guidelines, that among those who are moderate drinkers, continued consumption may provide a reduction of ischemic stroke risk." The continuing threat and devastating effect of stroke – as well as the unanswered scientific questions–assure us that there will be many more studies on this important topic as we move into the next century.

This scientific summary is for educational purposes only. For more information or a list of references, please contact Elisabeth Holmgren.

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