Drinking more than two alcoholic beverages daily in middle age may raise a person’s stroke risk more than traditional factors such as high blood pressure and diabetes, according to new research published online ahead of print January 29 in Stroke. “Alcohol consumption should be considered an age-varying risk factor for stroke,” reported the study authors.
In a study of 11,644 middle-aged Swedish twins who were followed for 43 years, researchers compared the effects of heavy drinking, which they defined as an average of more than two drinks daily, to those of light drinking, defined as less than half a drink daily.
The study’s main findings included the following observations:
- Heavy drinkers had about a 34% higher risk of stroke, compared with light drinkers.
- Midlife heavy drinkers (ie, between ages 50 and 70) were likely to have a stroke five years earlier in life, irrespective of genetic and early-life factors.
- Heavy drinkers had increased stroke risk in midlife, compared with people with other well-known risk factors like high blood pressure and diabetes.
- At around age 75, blood pressure and diabetes appeared to become two of the main influences on having a stroke.
Past studies have shown that alcohol affects stroke risk, but this study is the first to pinpoint differences associated 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 lead author Pavla Kadlecová, MSc, a statistician at St. Anne’s University Hospital’s International Clinical Research Center in Brno, Czech Republic.
Researchers analyzed results from the Swedish Twin Registry of same-sex twins who answered questionnaires between 1967 and 1970. All twins were younger than 60 at the start of the study. By 2010, the registry yielded 43 years of follow-up, including data on hospital discharge and cause of death. Researchers then sorted the data based on occurrence of stroke and covariates such as baseline age, sex, cardiovascular diseases, diabetes mellitus, stress reactivity, depression, BMI, smoking, and exercise.
Almost 30% of participants had a stroke. Participants were categorized as nondrinkers or light, moderate, or heavy drinkers, based on the questionnaires. Among monozygotic twin pairs, siblings who had a stroke drank more than siblings who hadn’t had a stroke, suggesting that midlife drinking raises stroke risk regardless of genetics and early lifestyle.
The study findings provide evidence for the American Heart Association’s recommended limit of two drinks per day for men and one for women. That limit is equivalent to 8 oz of wine (ie, two drinks) for a man and 4 oz of wine (ie, one drink) for a woman. “For mid-aged adults, avoiding [consumption of] more than two drinks per day could be a way to prevent stroke in later productive age (about 60s),” Ms. Kadlecová said.