According to the A new genetic analysis has found that although the risk of dementia increases with increased alcohol intake, even low alcohol intake can increase a person’s risk of developing the condition. The study, published in BMJ Evidence-Based Medicine, used both observational and genetic analyses. While the observational analysis found that moderate drinkers had a lower dementia risk than abstainers, the genetic analysis found that any alcohol intake was linked to an increased risk. “This is a highly important and influential finding. It challenges decades of observational research suggesting that light-to-moderate alcohol consumption may protect against dementia. By incorporating genetic analyses, which are less susceptible to confounding and reverse causation, the study demonstrates a likely causal relationship between alcohol and increased dementia risk at all levels of intake. This has direct implications for public health messaging and dementia prevention strategies.” — Dr. Steve Allder, consultant neurologist at Re:Cognition Health, who wasn’t involved in the study The effects of heavy drinking on the brain are well known. According to the Allder explained how alcohol damages the brain: “Alcohol is neurotoxic: it damages neurons, promotes brain atrophy, disrupts neurotransmitter systems, and accelerates vascular injury. Chronic use can impair thiamine metabolism, leading to cognitive deficits, while even lower levels have been linked to adverse brain imaging findings such as reduced gray matter volume.” “Alcohol also increases systemic inflammation and oxidative stress, both of which are implicated in neurodegeneration,” he added. Using questionnaires and the Alcohol Use Disorders Identification Test (AUDIT-C) clinical screening tool, they assessed participants’ drinking. They then monitored participants for an average of 4 years, during which time, 14,540 people developed dementia. In the observational analysis, they found U-shaped associations between alcohol use and dementia risk. Non-drinkers and heavy drinkers both had a higher dementia risk than those who drank fewer than seven drinks a week. However, the genetic analysis gave different results. Şebnem Ünlüişler, genetic engineer and chief longevity officer at the London Regenerative Institute, who was also not involved in the study, explained why: “Studies looking at alcohol and dementia can sometimes give conflicting messages. Observational research often suggests that light drinking might protect the brain, showing a U-shaped pattern where moderate drinkers seem at lower risk than heavy drinkers or abstainers. But this can be misleading. People who drink lightly often lead healthier lives — they may exercise more, eat better, have higher education, or enjoy stronger social connections, all of which reduce dementia risk. At the same time, some people stop drinking because of early health problems or subtle cognitive changes, making abstainers appear at higher risk.” “Genetic studies offer a clearer picture,” she told Medical News Today. “By using inherited genetic markers linked to alcohol use, researchers can estimate lifetime exposure without the bias of lifestyle or health differences.” Lead author, Dr. Anya Topiwala, BM BCh, DPhil, Wellcome Trust Career Development Fellow, Honorary Consultant Psychiatrist, Nuffield Department of Population Health, University of Oxford, UK, explained to MNT how the genetic risk for alcohol consumption was actually worked out by another “It’s determined using a genome-wide association study (GWAS). They take a huge sample of individuals and ask them how much they drink. They then look across peoples’ genomes, and test [whether] each genetic variant is more or less common in people who drink more or not. For alcoholic drinks per week they found [d]ifferent genetic variants that were more or less common with higher alcohol intake. Each only contributes a small effect, but we used these genetic variants to ‘proxy’ alcohol intake.” They found that, in those of European ancestry, a higher genetic risk for alcohol consumption was associated with an increased risk of all-cause dementia. Is alcohol harmless? “These [genetic] analyses consistently show that any alcohol, even in small amounts, raises dementia risk, with no protective effect at low levels. While light drinking may look harmless in some studies, the safest choice for your brain is to minimise or avoid alcohol entirely.” — Şebnem Ünlüişler Contrary to the observational analysis, the genetic analysis found no U-shaped association between alcohol use and dementia. This analysis found that dementia risk increased steadily with greater predicted alcohol consumption, and that there was no protective effect from low alcohol intake. Read the full article here
