The Not-So-Happy Hour

The risk of stroke is approximately double in the hour after consumption of an alcoholic drink, according a study reported online in the journal Stroke.  It’s long been known that heavy alcohol user increases the risk for ischemic stroke, while daily small quantities (less than 2 drinks) may decrease the risk.  This study, from Harvard Medical School, was designed to see whether alcohol increases the acute risk of stroke, i.e. the time between drink and first symptoms.

A total of 390 patients (209 men, 181 women) at 3 stroke centers were interviewed within an average of 3 days after their stroke.  Overall, 64% had consumed alcohol in the previous year – 12% drank at least once a day and 10% at least once a week.

When asked about their recent stroke and alcohol, the patients’ responses showed that 104 had a drink in the 24 hours before their stroke, and 14 had a drink within one hour of their stroke onset.  The likelihood of stroke was compared in each of these groups of patients.  Compared with times when no alcohol was being consumed, the risk of stroke was 2.3 times higher in the first hour, 1.6 times higher in the second hour, and 30% lower than baseline after 24 hours. 

These results were roughly the same, whether the drinks consumed were beer, wine, or liquor.  They were also unchanged when patients who’d been exposed to other possible risk factors for acute stroke (exercise, caffeine) had been eliminated. 

The findings suggest that the risk of stroke onset is increased in the hour after alcohol consumption.  It may possibly be related to short-term blood pressure increases and increased stickiness of blood platelets.  However, there has been some criticism of the study design and the conclusions drawn.  First, it was clearly a high-risk population (i.e. everyone had a stroke), so the risks are not applicable to the ‘general population’ – drinkers or not.  Then, the study was small, and depended on the subjects’ recall, which is often unreliable.  And, as one of the researchers pointed out, the risk of stroke for the average person in any given hour is extremely small, so even a doubling of the risk might only raise it to a 2-in-a-million chance.  I think I’m safe in having my evening gin-and-tonic.