A study by researchers at Oxford and Cardiff found drinking just three and a half glasses of wine a week is enough to raise the risk of dementia.
A study of more than 13,000 adults is the largest of its kind to show the link between even low levels of alcohol intake and damage to the brain.
Both men and women who drank just over one unit of alcohol a day suffered a decline in brain function over four years.
One unit of alcohol equates to one measure of spirits, half a small glass of wine or half a pint of beer.
Now researchers are calling for a “discussion” over whether Government guidelines of 14 unites a week should be lowered for older adults.
The Royal College of Psychiatrists are set to publish a review into the harm drinking causes to over-60s. It will be released next Wednesday.
Authors believe 14 units a week is an “unsafe” level for many older adults because of the increased risk of dementia and other illnesses, according to the Daily Mail.
Professor Simon Moore of Cardiff University said: “We’re drinking ourselves to stupidity. If you want to remain healthy in your later years you should really minimise how much you drink.
“If you’re planning on drinking more than ten grams a day (1.25 units) you’re increasing your risk of dementia. If, for example, last week you were drinking on average ten grams of alcohol a day, about a bottle of prosecco that week, but then next week you increase that to two bottles of prosecco, you’re putting yourself at significant risk.”
There are 61,000 new cases of dementia every year, and no cure. Study authors claim alcohol is contributing to the skyrocketing rates of new cases.
The study, which was published in the Journal of Public Health, followed 13,342 adults aged 40 to 73.
Participants took computer tests four and a half years apart that measured their brains’ ability to function. These tests are useful in predicting whether someone will develop dementia in later life.
Men and women who drank more than ten grams of alcohol a day performed significantly worse in the tests four years later than those who drank less often. The difference was even larger in those over 60.
There are two ways in which low-level drinking harms the brain. Firstly, as we get older, the brain loses its ability to generate new nerve cells, so damage is irreparable.
Secondly, doctors think alcohol prevents the brain from absorbing vitamin B1, which is crucial in helping the brain work.