Drinking more than the recommended weekly limits can harm a person's brain health, a new study has found.
The study found that alcohol consumption is associated with an increased risk of adverse brain outcomes and a steeper decline in cognitive abilities.
Experts from the University of Oxford and University College London studied 550 civil servants over a 30-year period, repeatedly assessing their alcohol consumption and cognition.
At the most recent review, the researchers examined images of the participants' brains - which enabled them to explore correlations between average alcohol use, cognition and brain structure.
They found that alcohol use was associated with reduced right hippocampal volume.
And 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.
Last year, the Government changed its guidance on drinking and urged both men and women to drink 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.
The authors wrote: "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.
"Alcohol might represent a modifiable risk factor for cognitive impairment, and primary prevention interventions targeted to later life could be too late."
In a linked editorial, Killian Welch, consultant neuropsychiatrist at the Royal Edinburgh Hospital, wrote: "(The) findings strengthen the argument that drinking habits many regard as normal have adverse consequences for health.
"This is important. We all use rationalisations to justify persistence with behaviours not in our long term interest. With publication of this paper, justification of 'moderate' drinking on the grounds of brain health becomes a little harder."
Commenting on the study, Dr Jennifer Wild, senior research fellow in clinical psychology, University of Oxford, said: "Medical science is under pressure to find modifiable risk factors for cognitive decline since dementia will be a global epidemic by 2050. Here the authors have discovered 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."