Drinking one or two cocktails a day may protect against dementia, while having three or more could increase risk, new research suggests. Investigators assessed the risk of dementia using changes in alcohol consumption in nearly four million people in Korea and found that after about 7 years, dementia was 21% less likely in mild drinkers and 17% less likely in moderate drinkers. Heavy drinking was linked to an 8% increased risk of getting the disease.

The findings were published in JAMA Network Open on February 6. According to CNN, lead author Dr. Keun Hye Jeon, assistant professor at CHA Gumi Medical Center in Gumi, South Korea, said in an email:

“We found that maintaining mild to moderate alcohol consumption as well as reducing alcohol consumption from a heavy to a moderate level were associated with a decreased risk of dementia.”

The new study examined the health records of people covered by the Korean National Health Insurance Service (NHIS) who get free medical examinations twice a year if they are 40 years or older. The current study looked at data collected between 2009 and 2011 and categorized people by their self-reported drinking levels. If a person said they drank about 0.5 ounces daily, they were considered “mild” drinkers. If they consumed the equivalent of two standard drinks in the U.S. (a standard drink is 12 ounces of regular beer, 5 ounces of wine or 1.5 ounces of distilled spirits), they were considered to be “moderate” drinkers. If the participants said they drank more than that, researchers considered them “heavy” drinkers.

The investigators compared the data to medical reports seven or eight years later to find out if anyone had been diagnosed with dementia. After adjusting for age, sex, smoking and exercise and other demographic factors, the scientists found people who said they drink at a mild level were 21% less likely to develop dementia than people who never drank. People who said they continued to drink two drinks a day were 17% less likely to develop dementia, the study found. But people who drank heavily as defined by three or more drinks daily, were 8% more likely to be diagnosed with dementia.

The new study also noted that starting to drink at a mild level was associated with a decreased risk of all-cause dementia and Alzheimer’s, “which to our knowledge has never been reported in previous studies,’ the authors wrote, according to CNN.

“The study was well done and is extremely robust with 4 million subjects, but we should be cautious not to overinterpret the findings,” said Dr. Richard Isaacson, a preventive neurologist at the Institute for Neurodegenerative Diseases of Florida and an Alzheimer’s disease expert. Isaacson points out that research has shown that people with the APOE4 gene variant, which raises your risk of Alzheimer’s disease, should not drink.

According to News-Medical.net, there are other caveats to the study findings. While mild alcohol consumption may reduce neuroinflammation, improve platelet function and increase levels of “good” HDL cholesterol, excess alcohol is a nerve poison and causes a deficiency in many nutrients. High alcohol levels enhance the accumulation of the abnormal tau protein in the brain, along with the death of cholinergic neurons, leading to a loss of acetylcholine, an important neurotransmitter molecule.

Also, the study did not discuss disease and death from non-dementia-related causes linked to alcohol consumption. One study published in March 2022 found that just one pint of beer or glass of wine a day can shrink the overall volume of the brain, with damage increasing with the number of drinks daily. Alcohol consumption has been linked to breast and other cancers, and consuming too much can lead to digestive problems, heart and liver disease, hypertension, stroke and a weakened immune system, says the Centers for Disease Control and Prevention.

“I’ve never personally suggested someone to start drinking moderate amounts of alcohol if they were abstinent,” says Isaacson. “But there’s really not a one-size fits all approach towards counseling patients on alcohol consumption.”