Even moderate drinking affects the brain
7th June 2017 – Heavy drinking is known to have an effect on the brain over time but now researchers say even moderate drinking can affect your thinking skills.
The new long-term study by researchers at the University of Oxford and University College London, supports the UK's new guidance on alcohol consumption introduced last year.
It says both men and women shouldn't drink more than 14 units of alcohol a week, that's equivalent to a bottle and a half of wine or 5 pints of export-type lager (5% abv).
Few studies have examined the effects of moderate drinking on the brain so the team of researchers set out to investigate if it had a harmful or beneficial association - or no association at all - with brain structure and function.
Moderate drinking for the purpose of the study was measured as 14-21 units per week, more than is now recommended.
The researchers used data on weekly alcohol intake and thinking skills measured over 30 years (1985-2015) on 527 mostly men, but also some women who were taking part in the Whitehall II study which looks at the impact of social and economic factors on long-term health.
Brain function tests were carried out regularly and at the end of the study (2012-15), participants underwent an MRI brain scan.
After adjusting for things that could have affected the results like, age, sex, smoking and medical history, the researchers found that higher alcohol consumption was associated with an increased risk of a form of brain damage that affects memory and spatial navigation - hippocampal atrophy which is also a marker of Alzheimer's disease.
While those consuming over 30 units a week were at the highest risk compared with abstainers, even those drinking moderately were 3 times more likely to have hippocampal atrophy compared with those who drank nothing.
The researchers also found there was no protective effect of light drinking (up to 7 units per week) over abstinence.
Higher consumption was also associated with a faster decline in language fluency - how many words beginning with a specific letter can be generated in 1 minute. However, no association was found with semantic fluency - how many words in a specific category can be named in 1 minute - or word recall.
The findings have been published in The BMJ (British Medical Journal).
Public health implications
Although this was an observational study, so no firm conclusions can be drawn about cause and effect, it has the advantage of having MRI scan images of the brain and being able to look at alcohol consumption over decades.
Consequently, the researchers say their findings have important public health implications for a large sector of the population.
In a linked editorial, Killian Welch, consultant neuropsychiatrist at the Royal Edinburgh Hospital, says the findings strengthen the argument that drinking habits many regard as normal have adverse consequences for health.