More than 1.5 million people were included in the study. A total of 3,153 had a stroke during the study.
People who were moderate to heavy drinkers for two or more years of the study were about 20% more likely to have a stroke than people who were light drinkers or did not drink alcohol. Light drinkers were those who drank less than 105 grams per week, or less than 15 ounces per day.
As the number of years of moderate to heavy drinking increased, so did the risk of stroke. People with two years of moderate to heavy drinking had a 19% increased risk, people with three years had a 22% increased risk and people with four years had a 23% increased risk. These results were after researchers accounted for other factors that could affect the risk of stroke, such as high blood pressure, smoking and body mass index.
The association was mainly due to an increased risk of hemorrhagic stroke, or stroke caused by bleeding in the brain.
For any type of stroke, people with four years of moderate to heavy drinking had a stroke rate of 0.51 per 1,000 person-years, compared to 0.48 for three years of drinking, 0.43 for two years, 0.37 for one year and 0.31 for none. Person-years represent both the number of people in the study and the amount of time each person spends in the study.
“Since more than 90% of the burden of stroke overall can be attributed to potentially modifiable risk factors, including alcohol consumption, and since stroke in young adults severely impacts both the individual and society by limiting their activities during their most productive years, reducing alcohol consumption should be emphasized in young adults with heavy drinking habits as part of any strategy to prevent stroke,” Choi said.
A limitation of the study was that only Korean people were included, so the results may not apply to people of other races and ethnicities. In addition, people filled out questionnaires about their alcohol consumption, so they may not have remembered correctly.