“These findings challenge the notion that low levels of alcohol are neuroprotective and suggest that public health efforts to reduce alcohol use disorder could significantly lower dementia incidence,” wrote the researchers in their study.
"Halving the population prevalence of alcohol use disorder may reduce dementia cases by up to 16%, highlighting alcohol reduction as a potential strategy in dementia prevention policies,” they added.
For the study, the researchers analyzed data from close to 600,000 adults aged between 56 and 72 years old from two large-scale population-based cohorts: one from the US and one from the UK. Participants in the US study were followed for an average of 4 years, and those in the UK: 12 years. Data included dementia diagnosis, genetic information, and alcohol consumption, which was gathered from questionnaires.
Over the follow-up period, 14,540 participants developed dementia, and 48,030 died. Whereas observational analyses found a higher risk among non-drinkers, heavy drinkers, and those with alcohol use disorder compared to non-drinkers, genetic analyses found a link between increased alcohol intake and higher risk for dementia without any protective effect at lower levels.
“While correlational observational data suggested a protective effect of light drinking, this could be in part attributable to reduced drinking seen in early dementia,” wrote the researchers, “Genetic analyses did not support any protective effect, suggesting that any level of alcohol consumption may contribute to dementia risk.”
In the genetic analysis, the researchers investigated genetic measures linked to three exposures: self-reported weekly drinks, problematic ‘risky’ drinking, and alcohol dependency. They found that higher genetic risk for all three exposures was linked to a higher risk of dementia, with dementia risk increasing alongside alcohol consumption. Each 1-3 more drinks per week was linked to a 15% higher dementia risk.
“Our findings highlight the importance of considering reverse causation and residual confounding in studies of alcohol and dementia, and they suggest that reducing alcohol consumption may be an important strategy for dementia prevention,” concluded the researchers.
Sources: EurekAlert, BMJ Evidence-Based Medicine
