As part of the study, researchers conducted a prospective cohort study of 64,338 men who participated in the 1991 China National Hypertension Survey. At baseline, all of the men were over 40 years old and free of stroke. They provided information about their demographic characteristics, medical history and lifestyle risk factors, including alcohol consumption.
Those who said they consumed more than 12 drinks per year were defined as drinkers, and then quantified the number of drinks they had each month.
Between 1999 and 2000, the researchers followed up with the study participants and determined all incidents of stroke. For every such incident and for each death, medical records and death certificates were obtained to verify the diagnosis. The researchers then analyzed the data to assess any relationship between alcohol consumption and stroke.
The study found that after adjusting for factors such as age, body mass index and geographic variation, the risk of stroke was higher among those who drank more alcohol.
For participants who had 1 to 6 drinks per week, the relative stroke risk was .92. It was 1.02 for those who consumed 7 to 20 drinks per week, and 1.22 for those consuming more than 21 drinks per week. Heavier drinking also correlated to higher risk of death by stroke.
"Alcohol consumption was significantly related to increased stroke incidence and mortality. At the top level of alcohol consumption (at least 35 drinks per week), risk of stroke incidence was 22 percent higher and risk of mortality was 30 percent higher than among non-drinkers," the authors reported.
The findings of the study were published online in the Annals of Neurology.