A new study led by the University of Oxford, Yale University, and the University of Cambridge has found that any level of alcohol consumption increases the risk of developing dementia. The research, published in BMJ Evidence-Based Medicine, challenges earlier suggestions that light-to-moderate drinking might protect against dementia.
The study analyzed data from over half a million participants in two large population studies: the US Million Veteran Program and UK Biobank. Researchers examined whether self-reported alcohol use was linked to a higher risk of various types of dementia. In addition, they used genetic analyses involving more than 2.4 million participants across 45 individual studies to help distinguish correlation from causation.
Initial observational analyses appeared to support previous findings that low and moderate drinking was associated with lower dementia risk compared to non-drinking or heavy drinking. However, the researchers noted that some current non-drinkers had previously been heavy drinkers, which could explain their increased risk compared to those who consistently drank at low levels.
Genetic analyses showed a different pattern. They revealed a continuous increase in dementia risk with greater alcohol intake, suggesting there is no safe level of alcohol consumption for brain health. A doubled increase in genetically-predicted risk for alcohol use disorder was linked to a 16% higher risk of dementia. Similarly, tripling the number of alcoholic drinks per week raised dementia risk by 15%. The study also found that people who later developed dementia tended to reduce their alcohol intake before diagnosis, which may have contributed to earlier beliefs about protective effects.
Dr Anya Topiwala, Senior Clinical Researcher at Oxford Population Health and lead author of the study, said: “Our findings challenge the common belief that low levels of alcohol are beneficial for brain health. 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 Stephen Burgess, Statistician at the University of Cambridge, added: “The random nature of genetic inheritance allows us to compare groups with higher and lower levels of alcohol drinking in a way that allows us to make conclusions that untangle the confusion between correlation and causation. 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.”
Dr Joel Gelernter, Professor at Yale University and senior author on the study, stated: “These results, which add to our understanding of the relationship between alcohol and dementia, have clinical implications - 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.”
The authors say these results reinforce growing evidence suggesting there may be no safe threshold for alcohol use when it comes to brain health and highlight the importance of strategies aimed at reducing overall alcohol consumption.
The full study is available in BMJ Evidence-Based Medicine under the title 'Alcohol use and risk of dementia in diverse populations: evidence from cohort, case–control and Mendelian randomisation approaches'.