What raises dementia risk? A drink a day, even social drinking can affect brain, says new study

Why is this study significant?

“Previous studies have linked heavy drinking with increased dementia risk. Moderate drinking findings have been more mixed. Now the genetic analyses suggested that even low alcohol intakes (or “social drinking”) could potentially increase dementia risk (to a small degree),” Anya Topiwala, honorary consultant psychiatrist at the University of Oxford and lead researcher told The Indian Express.

For decades, heavy or excessive alcohol use has been associated with brain atrophy and increased dementia risk. “Past observational studies even suggested that light or moderate alcohol consumption might offer some protection or a lower dementia risk compared to abstainers, but these findings were controversial and possibly biased by confounding factors, such as including former drinkers who stopped due to health reasons,” says Dr Shiva Kumar R, Head and senior consultant, Neurology, Manipal Hospital, Bengaluru.

This new research provides the strongest evidence yet that any amount of alcohol increases dementia risk and refutes earlier claims of a “protective effect” from moderate drinking. “What stands out for me is that it is the most comprehensive to date in ruling out a safe threshold for alcohol. Besides, it combined genetic and observational data from more than half a million adults and included genetic analyses of 2.4 million individuals. Earlier research lacked genetic data and often relied on problematic self-reports or failed to account for reverse causation (people who develop dementia may reduce drinking as their cognition declines),” adds Dr Shiva Kumar.

What does alcohol do to your brain?

Alcohol penetrates the blood-brain barrier and then interferes with the brain’s signalling system by disrupting the balance of neurotransmitters, the chemicals that communicate messages between nerve cells. It can lead to atrophy and reduce brain volume, particularly the white matter, which is made up of nerve fibres. This disruption affects communication between different brain regions, including those related to emotions, memory, processing and coordination.

Topiwala and her colleagues found that moderate alcohol intake was associated with smaller grey matter and increased iron in the brain, the deposits of which have been linked to neurodegenerative diseases like Alzheimer’s and Parkinson’s.

Does the study mean that every kind of drinker can develop dementia?

“There are a multitude of factors that contribute to dementia risk (age, genetics, smoking etc). Alcohol intake is one of these and controllable,” says Topiwala.

“Not every person is uniformly exposed to the risk of dementia with social drinking — certain genetic and individual factors can modify vulnerability,” explains Dr Shiva Kumar. “There is no evidence that any demographic or genetic subgroup is immune to increased dementia risk from alcohol consumption, including those who only drink socially or in moderation,” he adds. In short, there is no group for whom drinking is completely “safe.”

How to manage alcohol intake?

Experts recommend integrating alcohol reduction into broader dementia prevention programmes and healthy lifestyle routines. “Practitioners are advised to give clear, evidence-based counseling. The study shifts both public health and individual guidance toward minimizing or abstaining from alcohol as an important strategy for dementia prevention,” says Dr Shiva Kumar.

Arguing why a generalized directive cannot work Dr Topiwala says, “This is a personal choice in terms of how much risk you are willing to take. Current alcohol guidelines differ around the world and most do not take account of brain harm.”

Have the researchers quantified the lower risk percentage of dementia when people stop drinking alcohol? “No, it’s very difficult to do this. There are some studies in heavy drinkers suggesting at least partial brain recovery is possible,” she says.