Drinking Alcohol Temporarily Heightens Stroke Risk

Allison Gandey

July 22, 2010

July 22, 2010 — Drinking even small amounts of alcohol increases the risk for ischemic stroke, a controversial new study suggests. Results from the Stroke Onset Study show double the risk for stroke an hour after consuming as little as a single serving of wine, beer, or hard liquor.

Previous research has suggested that regular heavy drinking increases the risk for ischemic stroke, but other studies have linked light to moderate alcohol intake to a decreased risk.

Alcohol recommendations

"The evidence on heavy drinking is consistent," senior investigator Murray Mittleman, MD, from Harvard Medical School in Boston, Massachusetts, said in a news release. "Both in the long and short term it raises stroke risk, but we're finding it's more complicated with light to moderate drinking," he said.

The preliminary findings are published online July 15 in Stroke.

In this multicenter study, investigators interviewed 390 stroke patients about 3 days after hospitalization. The researchers used a case-crossover approach to compare alcohol consumption in the hour before stroke symptoms with the frequency of use during the past year.

They found that 64% of patients drank alcohol the year before their stroke. Some of these patients (27%) drank within 24 hours of their symptoms, and some patients (3.6%) had had a drink within 1 hour of stroke.

The researchers, led by Elizabeth Mostofsky, MPH, also at Harvard, report that the relative risk for stroke in the hour after drinking was 2.3 (95% confidence interval, 1.4 - 4.0; P = .002). They report that the relative risks were similar for different types of alcoholic beverages.

Small Study, Preliminary Findings

Asked by Medscape Medical News to comment, Markku Kaste, MD, from the Department of Neurology at Helsinki University Central Hospital in Finland, recommended that clinicians continue following American Heart Association guidelines, which suggest that alcohol may be consumed in moderation.

Why did this new study find even a single glass could increase the risk for stroke? Dr. Kaste said it could be a chance finding from such a small study, or the participants may have had other unrecognized risk factors. Dr. Kaste says he thinks it is unlikely that 1 drink could trigger stroke.

During an interview, William Weiner, MD, from the University of Maryland Medical Center in Baltimore, said he is concerned about the high number of preliminary association studies he is seeing lately.

"It seems like every time I turn around, I'm reading another association study in the field of neurology," Dr. Weiner said. "We're being told we need more of this or less of something else. Patients tend to get excited about these findings, but we need to be very cautious, because most will not turn out."

Dr. Weiner said he agrees such studies should be conducted and published, but he says the caveats must be emphasized. "It's important we let people know how early these investigations are."

The researchers acknowledge that many questions remain. Although this study suggested that even small amounts of alcohol may be problematic, Dr. Mittleman said this temporary increased risk may eventually be outweighed by the longer-term health benefits of moderate alcohol consumption. "The impact of alcohol on your risk of ischemic stroke appears to depend on how much and how often you drink," he said.

This study was supported by the American Heart Association in Dallas, Texas. The researchers have disclosed no relevant financial relationships.

Stroke. Published online July 15, 2010.

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