Drinking Too Much Alcohol (And Too Little) Is Linked to Dementia

To drink or not to drink when it comes to your health really depends on a few important factors, including how much you imbibe and what health issues you’re concerned about. Alcohol in moderation can lower the risk of heart disease for some people, as well as reduce the risk of type 2 diabetes and gallstones. But excessive drinking — more than about a drink a day for women and two drinks a day for men — is also linked to several types of cancer, including breast, colon, pharynx, larynx and esophageal. Too much alcohol can also take a toll on the liver.

Some studies have also suggested that moderate drinking may be good for the brain, but most of these focused on elderly people and their recent drinking habits, making it hard to draw any conclusions about the effect of lifetime drinking patterns. So Severine Sabia, a researcher at Inserm, and her colleagues analyzed data from a large UK database to track alcohol consumption from middle age and its effect on dementia in later life. In the study published in BMJ, among more than 9,000 middle-aged people ages 35 to 55, who were followed for about 23 years, those with drinking habits at the two extremes — people who abstained from drinking, as well as those who drank more than around 14 glasses of wine a week — showed higher risk of dementia than those who drank one to 14 glasses of wine a week.

Before you decide whether your own drinking habits put you at increased or decreased risk of dementia, there are a couple of things to remember. First, dementia was evaluated by medical records and death certificates; variations in how people categorized dementia could affect the results. And Sabia notes that the threshold of 14 glasses of wine (about 112g of alcohol) identified in the study is lower than what some countries recommend as healthy levels of alcohol. In the U.S., the standard alcoholic beverage contains about 14g of alcohol (almost twice that in the standard alcoholic drink in the U.K., for example), and the Centers for Disease Control and Prevention recommends women drink up to a drink a day, and men consume no more than two drinks a day.

In the study, people who drank more than 14 units of alcohol a week on average from midlife to older age had a 40% increased risk of developing dementia compared to people who drank less. For people drinking more than 14 units a week, for every seven unit increase (about half an alcoholic beverage) that they consumed, their risk of developing dementia increased by 17%.

“Excessive alcohol consumption is not included in the current dementia prevention guidelines,” says Sabia about many countries. “Our results show it to be a risk factor for dementia.”

Alcohol in moderation may be beneficial in improving blood circulation by influencing blood-clotting factors that can cause blockages in the heart as well as the brain; good blood flow can keep neurons healthy and able to communicate in their complex networks.

Excessive alcohol, however, can start to negatively affect healthy tissues, building up in toxic amounts that can compromise nerve function, for example.

But that doesn’t mean that abstaining will necessarily protect you from dementia. The study also found higher risk for people who abstained from alcohol; their risk of dementia from midlife to their later years was 74% compared to people who drank moderately. For them, Sabia believes a different mechanism may be at work. They may not be benefitting from the heart-related benefits linked to alcohol, including higher levels of good cholesterol and a healthier blood-clotting profile.

While the findings represent an association between alcohol consumption and dementia, and not a cause-and-effect relationship, Sabia believes they are enough for doctors to start a conversation with their patients about their drinking habits. “As far as the research in the risk factors for dementia, we are still at the beginning,” says Sabia. “There are several risk factors that are likely to be important in midlife a long time before the early stages of dementia appear later in life. I think alcohol should now be added to this list.”