Drinking more than two alcoholic beverages a day in middle age could have an even greater impact on stroke risk than high blood pressure and diabetes.

Past studies have linked alcohol consumption and stroke risk, but this was the first to determine how this effect varies with age, a news release reported.  

"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, a statistician at St. Anne's University Hospital's International Clinical Research Center in the Czech Republic.

To make their findings researchers looked at data from the Swedish Twin Registry of same-sex twins who answered questionnaires between 1967 and 1970 and included a follow-up stretching all the way to 2010. The database included 11,644 middle-aged Swedish twins.  The participants were categorized as light, moderate, heavy or non-drinkers based on the questionnaires.

About 30 percent of the participants suffered a stroke, and among the identical twin pairs those who had a stroke tended to drink more than their sibling. These findings suggest heavy middle-age drinking has raises stroke risk by 34 percent compared to light drinking habits. At about the age of 75, blood pressure and diabetes became higher stroke risk factors than alcohol consumption.

The findings add support to the American Heart Association's recommendation of not more than two drinks a day for men and one for women. Regular heavy drinking is also known to raise blood pressure and cause irregular heartbeats and heart failure.

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

The findings were published in a recent edition of the American Heart Association journal Stroke.