The average American has four alcoholic drinks each week. With research linking alcohol to brain damage and higher dementia risk, how much is OK to drink?
According to Homer Simpson, alcohol is “the cause of, and solution to, all of life’s problems.” While the patriarch of the Simpson family isn’t known for his intelligence, it turns out he was half right — alcohol may cause problems for the brain.
University of Oxford psychiatrist Anya Topiwala told Being Patient that drinking alcohol “can shrink the brain, worsen cognition, and increase the risk of dementia.” That’s bad news for the 65 percent of adults over 65 in the U.S. whose regular drinking habits exceed daily health guidelines. One in ten older Americans also report binge drinking — that’s downing five or more alcoholic drinks in one sitting for men, and four or more drinks for women.
What happens when you have a drink?
When people talk about drinking alcohol, they’re really referring to ethanol — the type of alcohol found in drinks. Other forms of alcohol, like methanol or isopropyl alcohol, are dangerous to consume.
When you drink alcohol, the ethanol is absorbed directly from the stomach into the blood vessels and reaches the brain within five minutes. From there, it only takes another five minutes for the alcohol to start affecting your reaction speed, judgment, and thinking.
Alcohol disrupts the communication of neuronal signals within the brain. In the short-term, it increases the activation of neurons that send signals to turn off other neurons or networks in the brain. Depending on how much alcohol you’ve drank, it can cause you to feel lightheaded, tipsy, confused, or nauseous. The liver only starts breaking down the alcohol in the bloodstream after twenty minutes, and it takes more than five hours for the alcohol to clear the body completely.
Drinking guidelines in the U.S.
The U.S. Dietary Guidelines lay out daily drinking limits which minimize the risks of alcohol.
Since beer, liquor, and other cocktails have varied amounts of alcohol, the U.S. and other countries have created a standard called an “alcoholic drink equivalent.” One drink equals about 14 grams or 0.6 fluid ounces of ethanol.
The daily limit for men is two drinks, while for women, it’s one.
Heavy drinking is another technical term that researchers use. For men, it refers to having five or more drinks in a single day, or 15 in a week. For women, the equivalent is four or more drinks in a day or eight in a week.
While it’s important to understand that even small amounts of alcohol are known to increase the risk of cancer, according to the National Institute on Alcohol Abuse and Alcoholism, people may want to avoid alcohol altogether if they have a medical condition that is worsened by drinking. Many of these conditions are also risk factors for dementia:
Long-term effects of alcohol on the brain and cognition
A 2022 study that examined 36,678 healthy middle-aged and older adults from the UK found that people who drank even one or two drinks a day had less overall brain volume. The participants showed shrinkage in the size of the gray matter — the neuronal signaling cells — as well as damage to the white matter — the tracts of nerve fibers that allow distant brain cells to communicate and exchange information.
Previous studies found that drinking leads to shrinkage of the hippocampus, which is instrumental in memory and learning but is also one of the first regions affected by Alzheimer’s and other forms of dementia.
Anya Topiwala said scientists don’t know why alcohol damages the brain, but there are many theories. Drinking could lead to a vitamin B1 deficiency, damage the brain cells directly, or increase inflammation.
Can alcohol cause cognitive impairment or dementia?
Alcohol use disorder is one of many conditions that can lead to mild cognitive impairment.
Researchers have found that people who have an alcohol use disorder show a broad range of deficits in executive function, memory, visuospatial reasoning, balance, and behavior in social situations.
Frequent drinking and alcohol addiction are linked to higher dementia risk. Topiwala said that researchers are currently conducting studies to figure out why that is, and testing whether alcohol affects Alzheimer’s pathology.
So far, some small studies find that alcohol doesn’t seem to affect the levels of Alzheimer’s biomarkers like beta-amyloid or tau but may increase the chances of developing Alzheimer’s and other dementias. A 2023 study found that around three percent of dementia cases in women and about eight percent of cases in men could be attributed to frequent drinking.
Alcohol-related dementias are directly caused by alcohol use and tend to have an earlier onset and slower progression than Alzheimer’s disease. Alcohol use disorder can also lead to a vitamin B1 deficiency, which can cause a rare neurodegenerative condition called Wernicke-Korsakoff syndrome; symptoms include amnesia, confusion, disorientation, and can lead to death.
“Alcohol also increases the risk of stroke, so vascular damage is another possible pathological process,” she said
Is moderate drinking protective of brain health?
Some studies suggest that drinking small amounts of alcohol is linked to a reduction in dementia compared to nondrinkers. Studies that looked at health records and surveyed people about their diet have found that people who drink moderate amounts of red wine might have a lower chance of developing dementia. So does that mean a little bit of alcohol may be good for the brain?
“This is the million dollar question,” Topiwala said. “I do not believe that [drinking small amounts of alcohol is protective] and think those were spurious findings resulting from the fact that people who drink small amounts of wine tend to be healthier and wealthier than those who don’t.”
Scientists have proposed other factors that might explain this paradox. Some people who report that they abstain from drinking may have been heavy drinkers early in life. Even though they don’t drink anymore, some of the damage caused by their past drinking could contribute to a higher risk of developing dementia. In other cases, the reason people aren’t drinking is because of underlying risk factors for dementia, like heart disease which predisposed people to a higher risk of dementia. In this case, the health condition and not the lack of drinking is the reason they’re at a higher risk.
If I quit drinking, does it reverse the effects on my brain?
Quitting alcohol can reverse some of the effects on the brain, but there aren’t very many studies, explained Topiwala.
“There are some studies in previously very heavy or dependent drinkers which show at least partial recovery,” she said.
Studies have found, for example, that cognitive function starts improving one year after you stop drinking. Parts of the brain important for cognitive function called the cortex, start to thicken and rebuild after just seven months of abstinence. More studies are needed to figure out why some people might recover faster than others, however, smokers don’t recover from alcohol-induced deficits as well as non smokers.
There’s an adage used in pharmacology: The dose makes the poison. Almost anything, including water, can be dangerous at high enough levels. But Topiwala said in her work she’s found no evidence any amount of alcohol is good for the brain. “Many now believe there is no ‘safe’ level of drinking.”
Thank you so much for this information.
Which will help me in my recovery from alcohol abuse
Hi Monica, we’re happy you found this article useful. Take care!
Grammar nerd here:
drink, drank, drunk
“No matter how much alcohol you have drunk” (is correct 🙂
I enjoy your column
Hi Connie, thank you for being here!