Drinking more than two alcoholic beverages daily in middle-age may raise your stroke risk more than traditional factors such as high blood pressure and diabetes, according to new research in the American Heart Association journal Stroke.

In a study of 11,644 middle-aged Swedish twins who were followed for 43 years, researchers compared the effects of an average of more than two drinks daily ("heavy ") to less than half a drink daily ("light drinking").

The study showed that:

  • Heavy drinkers had about a 34 percent higher risk of stroke compared to light drinkers.
  • Mid-life heavy drinkers (in their 50s and 60s) were likely to have a stroke five years earlier in life irrespective of genetic and early-life factors.
  • Heavy drinkers had increased in their mid-life compared to well-known risk factors like and diabetes.
  • At around age 75, blood pressure and diabetes appeared to take over as one of the main influences on having a stroke.

Past studies have shown that alcohol affects stroke risk, but this is the first study to pinpoint differences with age.

"We now have a clearer picture about these risk factors, how they change with age and how the influence of drinking alcohol shifts as we get older," said Pavla Kadlecová, M.Sc., a statistician at St. Anne's University Hospital's International Clinical Research Center in the Czech Republic.

Researchers analyzed results from the Swedish Twin Registry of same-sex twins who answered questionnaires in 1967-70. All twins were under age 60 at the start. By 2010, the registry yielded 43 years of follow-up, including hospital discharge and cause of death data.

Researchers then sorted the data based on stroke, high blood pressure, diabetes and other cardiovascular incidences.

Almost 30 percent of participants had a stroke. They were categorized as light, moderate, heavy or non-drinkers based on the questionnaires. Researchers compared the risk from alcohol and health risks like high blood pressure, diabetes and smoking.

Among identical twin pairs, siblings who had a stroke drank more than their siblings who hadn't had a stroke, suggesting that mid-life drinking raises stroke risks regardless of genetics and early lifestyle.

The study is consistent with the American Heart Association's recommended limit of two drinks a day for men and one for women. That's about 8 ounces of wine (two drinks) for a man and 4 ounces (one drink) for a woman.

Regular of any kind of alcohol can raise and cause heart failure or irregular heartbeats over time with repeated drinking, in addition to stroke and other risks.

"For mid-aged adults, avoiding more than two drinks a day could be a way to prevent in later productive age (about 60s)," Kadlecová said.

Journal information: Stroke

Provided by American Heart Association