Stroke: Alcohol increases the risk

A stroke is a serious life-threatening medical condition that happens when the blood supply to part of the brain is cut off. Poor lifestyle decisions can trigger a stroke and a study published in the Stroke: Journal of the American Heart Association shows just how quickly these negative effects can kick in.

The risk of stroke appears to double in the hour after consuming just one drink – be it wine, beer or hard spirits.

“The impact of alcohol on your risk of ischaemic stroke appears to depend on how much and how often you drink,” said Murray A. Mittleman, M.D., Dr.P.H., senior author of the Stroke Onset Study (SOS) and director of the Cardiovascular Epidemiology Research Unit at Beth Israel Deaconess Medical Center in the Harvard Medical School in Boston, Mass.

Prior to the SOS, researchers didn’t know if alcohol consumption had an immediate impact on ischaemic stroke (caused by a blood clot in a vessel in or leading to the brain), although modest alcohol use (less than two drinks per day) may potentially lower risk in the long term.

Researchers interviewed 390 ischemic stroke patients (209 men, 181 women) about three days after their stroke regarding many aspects of their lives.

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The patterns remained the same whether participants had consumed wine, beer or distilled spirits. When the researchers eliminated patients who had been exposed to other potential triggers (such as exercising vigorously or drinking a caffeinated beverage) just prior to their strokes, the alcohol connection didn’t change.

Only one participant had consumed more than two drinks in the hour preceding the stroke, and removing that data didn’t alter the pattern.

“The evidence on heavy drinking is consistent: Both in the long and short term it raises stroke risk,” Mr Mittleman said.

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“But we’re finding it’s more complicated with light to moderate drinking. It is possible that the transiently increased stroke risk from moderate alcohol consumption may be outweighed by the longer term health benefits.”

Just after drinking, blood pressure rises and blood platelets become stickier, which may increase the possibility of a clot forming.

However, consistent use of small amounts of alcohol is associated with beneficial changes in blood lipids and more flexible blood vessels, which may reduce risk overall.

“At this point we don’t have enough evidence to say that people who don’t drink should start, or that people who drink small amounts – on the order of one drink a day – should stop,” Mr Mittleman said.

A more conclusive answer would require a controlled study in which some people are randomly selected to consume alcohol while others don’t, he said.

It’s important to note the findings may not apply to patients with severe stroke.

Unchangeable risk factors

It’s not possible to completely prevent strokes because some things that increase your risk of the condition cannot be changed.

According to the NHS, these include:

  • Age – you’re more likely to have a stroke if you’re over 55, although about one in four strokes happen to younger people
  • Family history – if a close relative (parent, grandparent, brother or sister) has had a stroke, your risk is likely to be higher
  • Ethnicity – if you’re south Asian, African or Caribbean, your risk of stroke is higher, partly because rates of diabetes and high blood pressure are higher in these groups
  • Your medical history – if you have previously had a stroke, transient ischaemic attack (TIA) or heart attack, your risk of stroke is higher.

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