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Heavy drinking is the single most modifiable risk factor for dementia. Here are five things everyone needs to know about the effects of excessive alcohol on the brain.

Heavy drinking is a risk factor for every form of dementia, but especially for early-onset dementia. A study of 30 million people in France found that alcohol abuse causes a three-fold greater risk of dementia  Half of the cases of dementia related to alcohol abuse produce symptoms before the age of 65. In the words of Dr. Michaël Schwarzinger, lead scientist for the French study, cited in Medscape News: 

"If people are consuming more than a couple of alcoholic drinks a day, they could be putting themselves at increased risk of dementia. Our results suggest that one of the best things you can do for your brain health is to cut down your alcohol intake."

There are at least four ways excessive consumption of alcohol increases the risk of dementia. First, alcohol is directly toxic to brain tissue. Both alcohol and the byproduct acetaldehyde damage the structure and function of brain tissue. Secondly, heavy drinking is associated with deficiencies of vitamin B1, which can lead to Wernicke–Korsakoff syndrome. Thirdly, alcohol intoxication is a risk factor for events that can damage the brain, including traumatic brain injury and encephalopathy associated with liver failure. Finally, alcohol abuse is associated with depression, lower educational attainment, and smoking tobacco, other known risk factors for dementia.

Here are five things to consider about alcohol abuse and the brain:

1. Drinking excessively increases the risk of early-onset dementia for both men and women

In the French study, men who drink more than two drinks a day were 3.36 times more likely than expected to develop dementia before the age of 65. Women who drank excessively were 3.34 times more likely to develop early-onset dementia. "Dementia" encompassed all forms of the disease, including Alzheimer's.

2. Alcohol-related dementia can occur as early as age 27

Alcoholic dementia due to alcohol-related brain damage is most common at ages 57 through 62, but there are a significant number of cases that begin after the age of 50. The average age of onset of other forms of dementia is 82. Twenty-five years of life can be lost to alcohol abuse.

3. The effects of excessive drinking are additive to other risk factors for dementia

Drinking too much adds to the risk of dementia posed by smoking tobacco, uncontrolled high blood pressure, uncontrolled diabetes, a history of hemorrhagic or ischemic stroke,  peripheral artery disease, atrial fibrillation, heart failure, less education, depression, hearing loss, chronic kidney failure, hypothyroidism, and infectious disease of the central nervous system.

4. Complete abstinence from alcohol does not offer maximum protection against dementia

A meta-analysis of studies of alcoholic dementia found that the optimal level of consumption of alcohol is:

  • No binge drinking, ever.
  • An average alcohol consumption of six grams per day. 

That is about one beer or one glass of wine or one shot of liquor every other day.  The risk of alcoholic dementia is significantly raised at 23 drinks a week, or about three drinks a day. Total abstainers have slightly higher rates of dementia than light to moderate drinkers. Moderate drinkers (more than zero drinks a week but no more than seven drinks a week for women or 14 drinks a week for men) have slightly reduced risk of developing dementia of any kind. But heavy drinkers have greatly increased risk of developing dementia, both alcoholic dementia and Alzheimer's and other forms of dementia. 

5. The risk of alcoholic dementia may be offset by getting enough of the B vitamins

Heavy drinkers tend to be deficient in the B vitamins. Vitamin B6, vitamin B12, and folate are critical to reducing the production of an inflammatory and brain-toxic compound called homocysteine. This compound can oxidize and damage the fatty linings of neurons. Scientists don't really know whether supplementing with vitamins B6 and B12 reduces the risk of dementia, but one French study suggests that making sure to get enough folic acid reduces the risk of alcoholic dementia and other forms of dementia by 50 percent. An inexpensive B vitamin supplement might wipe out half the increased risk of alcoholic dementia.

It isn't necessary to megadose. In many countries in the European Union, it is not even possible to buy B vitamins that contain more than the recommended daily intake (RDI). However, making sure to get the recommended daily dose, and making sure to get it every day, is enough to make a difference.

Some people need a special form of folate known as methylfolate. That is because they lack one or more of the genes the body needs to make the enzyme methylene tetrahydrofolate reductase (MTHFR), which activates the form of the B vitamin found in food into a form that cells can use to make enzymes for energy production. North Americans who are constantly exposed to the "wrong" form of folic acid in fortified flour, rice, and cereals who have variations of the MTHFR genes may especially benefit from methyfolate supplements. They are inexpensive and available in health food stores and online.

  • Gupta S Warner J Alcohol-related dementia: a 21st-century silent epidemic?. Br J Psychiatry. 2008. 193: 351-353.
  • Schwarzinger M, Pollock BG, Hasan OSM, Dufouil C, Rehm J
  • QalyDays Study Group. Contribution of alcohol use disorders to the burden of dementia in France 2008-13: a nationwide retrospective cohort study. Lancet Public Health. 2018 Mar.3(3):e124-e132. doi: 10.1016/S2468-2667(18)30022-7. Epub 2018 Feb 21. Verbaten MN Chronic effects of low to moderate alcohol consumption on structural and functional properties of the brain: beneficial or not?. Hum Psychopharmacol. 2009. 24: 199-205 PMID: 29475810.
  • Photo courtesy of SteadyHealth

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