The study found alcohol consumption is associated with an increased risk of adverse brain outcomes and steeper decline in cognitive abilities.
Experts from the University of Oxford and University College London studied 550 people over a 30-year period, repeatedly assessing their alcohol consumption and cognition.
The experts examined images of the participants’ brains – which enabled them to explore linked between average alcohol use, cognition and brain structure.
They found that alcohol use was associated with reduced right hippocampal volume – oart of the brain.
Researchers said the more a person drank, the more likely they were to have hippocampal atrophy – a form of brain damage that affects memory and spatial navigation, which is regarded as an early marker for Alzheimer’s disease.
Even moderate drinkers – classed for the study’s purposes as drinking between 14 and 21 units a week – were three times more likely to have hippocampal atrophy than abstainers.
“Our findings support the recent reduction in UK safe limits and call into question the current US guidelines, which suggest that up to 24.5 units a week is safe for men, as we found increased odds of hippocampal atrophy at just 14-21 units a week, and we found no support for a protective effect of light consumption on brain structure,” the authors of the study wrote.
“Alcohol might represent a modifiable risk factor for cognitive impairment, and primary prevention interventions targeted to later life could be too late.
Current alcohol guidelines in the UK state people should consume no more than 14 units each week – the equivalent of six pints of average strength beer.
Previously it was recommended that men should consume no more than 21 units and women should not drink more than 14 units each week.
The decision to hone in the recommended limits was made due to links made between alcohol consumption and cancer. But the authors of the latest study, published in The British Medical Journal, said their findings support the reduction in recommended weekly limits for brain health as well.
They also found that very light drinking – classed as drinking between one and six units a week – had no protective effect compared to abstinence.
The brain images, taken using MRI scanners, also showed that those who consumed high amounts of alcohol were also more likely to have reduced white matter integrity.
These drinkers also showed a faster decline in language fluency – tested by how many words beginning with a specific letter can be generated in one minute.
Dr Jennifer Wild, senior research fellow in clinical psychology, University of Oxford said the study reveals a ‘robust link’ between what most people would consider normal levels of alcohol consumption and later degeneration of core brain regions linked to memory function.
“The results are encouraging since they suggest that reducing alcohol consumption today could prevent or delay the onset of diseases linked to hippocampal atrophy, such as Alzheimer’s. But the study needs to be replicated and, importantly, with women. Most of the sample in this study were men.”
Dr Doug Brown, director of research and development at the Alzheimer’s Society, added: “There’s no need to fret about whether to abstain from alcohol altogether as long as you stay within the new (2016) recommended guidelines.
“Further research is needed to better understand whether there is any relationship between light or moderate alcohol consumption, damage to the brain and a person’s risk of developing dementia. If you are worried about you or someone else, speak to your GP.”
Dr David Reynolds, Chief Scientific Officer, Alzheimer’s Research UK, warned people against exceeding the recommended alcohol levels.
“Studies like this, which monitor lifestyle and health over many years, are extremely useful for unpicking factors that could influence the long-term functioning of the brain, but they cannot prove cause and effect.
“More research is vital if we are to more fully understand the effects drinking alcohol can have on the brain and how it might affect the risk of diseases like Alzheimer’s.”