It's hardly a surprise that too much alcohol is bad for the body, including the brain. But a new study published this week in The Lancet suggests that even doctors are underestimating its impact on our risk of developing dementia.
The researchers looked at a nationwide, anonymous database of more than 30 million adult French hospital patients who were discharged sometime between 2008 to 2013. They excluded those at risk of developing rare forms of dementia, such as those brought on by infectious diseases like HIV or other neurological disorders.
Narrowing in on the over one million patients newly diagnosed with dementia during that time, the researchers found that heavy alcohol use was a substantial risk factor for every common type of dementia, particularly early-onset cases caught before the age of 65. More than half of the 57,000 patients diagnosed with early-onset dementia - 57 per cent - showed signs of alcohol-related brain damage or were diagnosed with an alcohol use disorder at the same time.
All told, they estimated that people with diagnosed alcohol problems were more than three times likely to develop any kind of dementia earlier, and over twice as likely to develop forms of dementia not typically associated with alcohol, such as Alzheimer's.
Doctors have long known that heavy alcohol use can affect our brain health negatively, while the occasional drink seems to boost it (how occasional depends on who you're asking this week). But the researchers believe that alcohol still hasn't gotten its proper due when it comes to dementia. They note that alcohol wasn't even included as a preventable risk factor in a comprehensive report on dementia published by The Lancet last year. And rather than just being one of many things that can affect a person's dementia risk, they think alcohol use might actually represent the single largest preventable factor, topping smoking, depression and hypertension.
"The findings indicate that heavy drinking and alcohol use disorders are the most important risk factors for dementia, and especially important for those types of dementia which start before age 65, and which lead to premature deaths," said study co-author Dr Jürgen Rehm of the Center for Addiction and Mental Health (CAMH), a teaching mental health hospital in Toronto, Canada, in a statement. Rehm is the director of the CAMH's Institute Institute for Mental Health Policy Research.
Men were much more likely to suffer alcohol use disorder or alcohol-related brain damage as well as early-onset dementia - they represented two-thirds of either diagnosis among those under the age of 65. But the overall risk caused by alcohol seemed to be the same for both men and women. And former heavy drinkers who reported quitting drinking were less likely to die than current heavy drinkers, but their risk of early-onset dementia remained the same.
It isn't just the toxic effects of alcohol that seem to raise our risk of dementia. The researchers found that alcohol use was linked to other risk factors too - heavy drinkers were also more likely to smoke and to be depressed. That ideally means that taking care of someone's problems with alcohol can also help them in other ways. But that also means it's harder to pinpoint the direct role it's playing on the brain.
Still, Rehm and his team hope their findings galvanise doctors and policymakers to become more gung-ho about keeping people's alcohol consumption in check. Not only through more dedicated efforts to get people into treatment programs, but also through policies such as increased alcohol taxes and advertising bans.
"If all these measures are implemented widely, they could not only reduce dementia incidence or delay dementia onset, but also reduce all alcohol-attributable morbidity and mortality," they wrote.