Drinking any quantity of alcohol could increase the risk of developing dementia, new research has shown.
The study, led by researchers at the University of Oxford, Yale University and the University of Cambridge, analysed data from more than 559,000 people in the UK Biobank and the US Million Veteran Programme. Over the follow-up period, 14,540 participants developed dementia.
The results of the observational data were striking. Heavy drinkers, defined as consuming 40 or more drinks a week, as well as non-drinkers, had a 41 per cent higher risk of developing dementia compared with light drinkers, who had fewer than seven drinks a week. For those who were alcohol dependent, the risk rose to 51 per cent.
But the researchers also carried out genetic analysis, using genome-wide association studies (GWAS) of 2.4 million people to untangle correlation from causation. They assessed three measures: self-reported weekly drinks, risky drinking and alcohol dependency.
In each case, a higher genetic risk for alcohol consumption was associated with a higher risk of dementia. The authors said this evidence undermined the idea that low levels of alcohol can protect the brain.
Researchers have previously cast doubt on findings that groups who do not drink alcohol at all appear to have worse health outcomes in observational studies. This is due to the so-called “sick quitter” effect, where people who stop drinking due to illness are grouped with lifelong non-drinkers.
A 2016 analysis also found that once former drinkers were excluded, the apparent protective effect of light drinking largely disappeared.
Dr Anya Topiwala, senior clinical researcher at Oxford Population Health and consultant psychiatrist, said these latest findings “challenge the common belief that low levels of alcohol are beneficial for brain health”.
She said: “Genetic evidence offers no support for a protective effect, in fact, it suggests the opposite.
“Even light or moderate drinking may increase the risk of dementia, indicating that reducing alcohol consumption across the population could play a significant role in dementia prevention.”
Dr Joel Gelernter, professor at Yale University and senior author of the study, said: “There was a time when medical knowledge seemed to support that light drinking would be beneficial to brain health, and this work adds to the evidence that this is not correct.”
Dr Stephen Burgess, statistician at Cambridge, added: “Our findings do not only hold for those who have a particular genetic predisposition, but for anyone who chooses to drink, our study suggests that greater alcohol consumption leads to higher risk of dementia.”
Alzheimer’s Research UK said the work added to the evidence linking alcohol to dementia risk, though it stressed more research was needed.
According to the Alzheimer’s Society, around 982,000 people are currently living with dementia in the UK, a figure projected to rise to about 1.4 million by 2040.
