The results of the study - 'Moderate alcohol consumption as risk factor for adverse brain outcomes and cognitive decline: longitudinal cohort study' - support the recent reduction in alcohol guidance in the UK and raise questions about the current limits recommended in the US, say the authors.
Heavy drinking is known to be associated with poor brain health, but few studies have examined the effects of moderate drinking on the brain - and results are inconsistent.
So a team of researchers based at the University of Oxford and University College London set out to investigate whether moderate alcohol consumption has a beneficial or harmful association - or no association at all - with brain structure and function.
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.
- Dr Anya Topiwala
They used data on weekly alcohol intake and cognitive performance measured repeatedly over 30 years (1985-2015) for 550 healthy men and women who were taking part in the Whitehall II study.
This study is evaluating the impact of social and economic factors on the long term health of around 10,000 British adults.
Participants had an average age of 43 at the start of the study and none were alcohol dependent. Brain function tests were carried out at regular intervals and at the end of the study (2012-15), participants underwent an MRI brain scan.
Several factors that could have influenced the results (known as confounding) were taken into account, such as age, sex, education, social class, physical and social activity, smoking, stroke risk and medical history.
After adjusting for these confounders, the researchers found that higher alcohol consumption over the 30 year study period was associated with increased risk of hippocampal atrophy - a form of brain damage that affects memory and spatial navigation.
While those consuming over 30 units a week were at the highest risk compared with abstainers, even those drinking moderately (14-21 units per week) were three times more likely to have hippocampal atrophy compared with abstainers.
There was no protective effect of light drinking (up to 7 units per week) over abstinence.
Higher consumption was also associated with poorer white matter integrity (critical for efficient cognitive functioning) and faster decline in language fluency (how many words beginning with a specific letter can be generated in one minute).
But no association was found with semantic fluency (how many words in a specific category can be named in one minute) or word recall.
The authors point out that this is an observational study, so no firm conclusions can be drawn about cause and effect, and say some limitations could have introduced bias. However, key strengths include the information on long term alcohol consumption and the detailed available data on confounding factors.
As such, they say their findings have important potential public health implications for a large sector of the population.
“Alcohol might represent a modifiable risk factor for cognitive impairment, and primary prevention interventions targeted to later life could be too late,” they conclude.
In a linked editorial, Killian Welch, consultant neuropsychiatrist at the Royal Edinburgh Hospital, says these findings “strengthen the argument that drinking habits many regard as normal have adverse consequences for health.”
This is important, he adds. “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.”
Read more about Dr Anya Topiwala
Read the linked Editorial in BMJ
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The Guardian, 07/06/2017, Even moderate drinking can damage the brain over time, researchers claim
Drinking even moderate amounts of alcohol can damage the brain and impair cognitive function over time, researchers have claimed. While heavy drinking has previously been linked to memory problems and dementia, previous studies have suggested low levels of drinking could help protect the brain. But the new study pushes back against the notion of such benefits. ‘We knew that drinking heavily for long periods of time was bad for brain health, but we didn’t know at these levels,’ said Anya Topiwala, a clinical lecturer in old age psychiatry at the University of Oxford and co-author of the research.
Private Eye, 16/06/2017 1446, p.19, "Apparently, even droderate minking bamages the drain."
The Times, 07/06/2017, Two glasses of wine a night can damage brain
Daily Telegraph, 07/06/2016, Glass of wine a day can harm the brain
i, 07/06/2016, Six glasses of wine a week ‘increases brain damage risk’
Spiegel online, 07/06/2017, Schon kleine Alkoholmengen könnten Gehirn verändern
Daily Mail, 07/06/2017, How nightly tipple in middle-age can shrink your brain
CNN (USA), 06/06/2017, Moderate drinking may alter brain, study says
Reuters, 06/06/2017, Even moderate drinking linked to changes in brain structure, study finds
Newsweek (USA), 06/07/2017, ALCOHOL AND BRAIN DAMAGE: MODERATE DRINKING LINKED TO COGNITIVE DECLINE
The Sun, 07/06/2017, Dementia linked to 6 pints wk
Daily Express online, 07/07/2016, Dementia and alcohol link revealed: You should only be drinking THIS much
USA Today, 06/06/2017, Study: Even moderate drinking might be bad for aging brains
Japan Times, 07/07/2016, ‘Moderate’ drinking linked to brain damage: study
Hindustan Times (India), 07/06/2017, Moderate drinking linked to brain damage, decline in mental skills, finds study
Herald Sun (Australia), 06/06/2017, Moderate drinking linked to brain changes
NEWS.com.au (Australia), 06/06/2017, Moderate drinking linked to brain changes
New Straits Times (Malaysia), 07/06/2017, Even moderate drinking linked to changes in brain structure, study finds
Daily Telegraph Australia, 07/06/2017, Moderate drinking linked to brain changes
DNA India, 07/06/2017, Even moderate drinking linked to changes in brain structure, study finds
The Australian, 07/06/2017, Moderate drinking linked to brain changes
Brisbane Courier-Mail (Australia), 07/06/2017, Moderate drinking linked to brain changes
Deccan Chronicle (India), 07/06/2017, Moderate drinking leads to changes in brain structure
Business Standard India, 07/06/2017, Even moderate boozing can risk your mental health: Study
Economic Times (India), 07/06/2017, Even moderate drinking can cause brain damage and decline in mental skills
TV: ITV 1, Good Morning Britain, 07/06/2017, 06:10
Daily Express online, 07/06/2017, Dementia and alcohol link revealed: You should only be drinking THIS much
International Business Times UK online, 07/06/2017, Even moderate alcohol consumption affects your brain and increases risk of Alzheimer's disease
South China Morning Post online (Hong Kong), 07/06/2017, Even moderate drinking can damage the brain, researchers now say
DNA India online, 07/06/2017, Even moderate drinking may harm brain health: study
Business Standard India online, 07/06/2017, Even moderate drinking may harm brain health: study
Financial Express online (India), 07/06/2017, Even moderate drinking may harm brain health: Study
Japan Times online, 07/06/2017, 'Moderate' drinking linked to brain damage: study
International Business Times online, 07/06/2017, Social Drinking Might Cause Dementia, New Study Finds
CBS News online (US), 07/06/2017, Even moderate drinking could harm the brain
CBC online (Canada), 07/06/2017, Even moderate drinking linked to changes in brain structure
Huffington Post (US), 07/06/2017, Even Moderate Drinking Linked To Changes In Brain Structure
Globe & Mail online (Canada), 07/06/2017, Even moderate drinking linked to changes in brain structure, study finds
San Francisco Chronicle online (US), 07/06/2017, Moderate drinking can harm brain, study says
Radio: BBC Radio Oxford, Charles Nove, 08/06/2017, 06:03
TV: BBC 1 South, Breakfast, 08/06/2017, 06:57
Radio: BBC World Service, Newsday, 07/06/2017, 07:33, 07:51
PBS online, 08/06/2017, Even moderate drinking may expedite brain decline
The Independent, 08/06/2017, Moderate drinking linked to decline in brain health, finds study
Oxford Mail, 09/06/2017, p.20, Moderate levels of drinking ‘can damage brain
Scientific American, 11/06/2017, Even a Moderate Amount of Drinking Could Cause Brain Decline