Modifiable risk factors for dementia such as heavy alcohol consumption, have been documented from previous research studies. However, the relationship between light to moderate drinking and dementia risk was not as well established until very recently, in a study by Zheng and colleagues set to be published in the Lancet in October 2024. A linear relationship between alcohol consumption and dementia was found among current drinkers; the findings suggest that there is no safe level of alcohol consumption.
Dementia contributes towards disease mortality and morbidity yearly. Leading data and analytics company GlobalData‘s epidemiologists predict that in the UK there will be just over 827,000 total prevalent cases of dementia in men and women aged 60 and above, and that number is predicted to increase to 995,000 cases by the end of 2032.
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Traditional epidemiology studies that have assessed the relationship between alcohol consumption and dementia have been subject to bias and confounding factors that are associated with observational studies. The study by Zheng and colleagues is unique in that it uses Mendelian randomisation as a method of analysis. This type of analysis gives a robust understanding of exposure on outcome of interest relationship; it can be best described as a genetic randomised controlled trial. In this study, data from 2006 to 2010 on 313,958 White British current drinkers in the UK was extracted from the UK Biobank. Participants were followed for an average of 13.2 years, until 2021. The baseline characteristics assessment found that 48.6% of current drinkers consumed more than the recommended amount of alcohol, 14 units per week. Additionally, men represented a higher proportion of the unsafe alcohol consumption group, whereas women represented a higher proportion of the safe alcohol consumption group. The median weekly alcohol consumption was 13.60 units for men and women. A significant causal and linear relationship between alcohol consumption among current drinkers and dementia risk was found. The lowest dementia risk was found for alcohol consumption of 11.9 units per week, which is lower than the recommended amount for safe consumption. The results from this study support findings from meta-analyses of systematic literature reviews, which have looked at alcohol consumption among current drinkers. As previously noted, conventional epidemiology studies are susceptible to bias and for this reason past studies have not recommended abstinence from alcohol for current drinkers as the causality of the relationship had not yet been established. Due to this, there could also be other unexplored lifestyle factors that contribute to greater dementia risk than light to moderate alcohol consumption. Findings should be interpreted with caution, taking bias and confounding factors into account, and considering that these findings can be generalised to current drinkers only. Regardless, the results offer new insight into the relationship between current drinkers and dementia risk, and can help to inform drinking guidelines in the UK.
