Cutting back on the final drink of the evening could substantially improve brain health, scientists have said. A major study of more than 36,000 adults suggests that the negative effects of alcohol consumption grow stronger with each additional drink. So those who drink several units each day potentially have the most to gain by reducing their drinking. “There is some evidence that the effect of drinking on the brain is exponential,” said Dr Remi Daviet, the study’s first author, who is based at the University of Wisconsin-Madison. “So, one additional drink in a day could have more of an impact than any of the previous drinks that day. That means that cutting back on that final drink of the night might have a big effect in terms of brain ageing.” The study found that the more a person drinks the smaller their brain and that there was less connectivity in the brain’s white matter. Even modest levels of drinking – a few glasses of wine a week – appeared to carry a risk. And the link between alcohol consumption and reductions in overall brain volume grew stronger the greater the level of alcohol consumption. The study follows previous work showing links between alcohol consumption and brain health. But it was unclear whether moderate levels of drinking had an impact – some had even suggested that light drinking could be beneficial. The NHS recommends not to drink more than 14 units a week on a regular basis, although states that there is no completely safe level of drinking. The latest study used a dataset of MRI scans from more than 36,000 adults in the UK Biobank and the sheer size of this cohort allowed the relationship between drinking and brain health to be examined in much greater detail. The research showed a negative association between even one drink a day and brain volume and the link grew stronger the greater the level of alcohol consumption. In 50-year-olds, increasing average drinking from one alcohol unit (half a pint of beer) a day to two units (a pint of beer or a glass of wine) was associated with changes in the brain equivalent to ageing two years. Going from two to three alcohol units at the same age was like ageing three and a half years. “It’s not linear,” said Daviet. “It gets worse the more you drink.” The study shows an association between drinking and brain volume, rather than proving that this was the underlying cause. “Our study does not randomly assign people to drink, this would not be ethical to do,” said Dr Reagan Wetherill, an assistant professor of psychiatry at the University of Pennsylvania Perelman School of Medicine and a co-author. However, there are plausible reasons for thinking that alcohol has a negative impact on the brain. Alcohol intoxication activates pro-inflammatory enzymes in the brain, Wetherill said, and this could lead to the loss of grey matter and the structure of white matter connection in the brain being impaired. In future, the authors hope to look in more detail at drinking patterns, including whether drinking one beer a day is better than drinking none during the week and then seven on the weekend. The findings are published in the journal Nature Communications.