A new study published last week in the journal Lancet Public Health found that “excessive alcohol use could increase the risk of all types of dementia, particularly early-onset dementia.”1 Those with Parkinson’s and Huntington’s were excluded from the study.

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Looking at over 1 million adults released from French hospitals between 2008 and 2013,  who had been diagnosed with dementia, the researchers found that “alcohol-use disorders were diagnosed in 16.5% of the men with dementia and 4% of the women with dementia — over twice as much as in those without dementia for both sexes.”2 (Researchers defined “alcohol-use disorders” as chronic use or alcohol dependence.)

Lead author of the study, Dr. Michael Schwarzinger, said, “The most novel result is the large contribution of alcohol-use disorders to the burden of dementia over the lifespan. Given the strength of the association, what is the most surprising to me is that alcohol-use disorders had received so little interest in dementia research and public health policies.”3

How alcohol might damage the brain

There are a couple ways that heavy alcohol use could cause dementia:4
  • ethanol and its byproduct acetaldehyde are known to have a toxic effect on the brain that can lead to long-term structural and functional brain damage
  • heavy alcohol use can lead to a condition called hepatic encephalopathy, characterized by a loss in brain function due to increases of ammonia in the blood caused by liver damage
  • heavy drinkers are often people with less education, smoking habits, and/or depression, all of which are risk factors for dementia onset
“Though heavy alcohol use increased the risk of dementia in general, the association was shown to be stronger in men. When other factors were not controlled for, heavy drinking was associated with a higher risk of dementia among both men and women. In men, the risk was increased by a factor of 4.7, while in women, it increased by a factor of 4.3.
But even when the researchers controlled for factors like high blood pressure, obesity and tobacco smoking, heavy alcohol use was still associated with a more than threefold increase in dementia among both sexes. The study also showed that the average age of dementia onset differed between men and women. Men were more likely to develop it a younger age and women at an older age.”5
There are some cautions though. Dr. Kostas Lyketsos, a neuropsychiatry professor and director of the Johns Hopkins Memory and Alzheimer’s Treatment Center who was not involved in the study warns that while the study was among the largest of its kind that fact alone could leave it open to selection bias. He also cautioned that this was a sample of hospitalized individuals and it’s very unusual for people with dementia, at least in the milder stages, to be hospitalized.

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Another issue, according to Schwarzinger, is that alcohol use wasn’t “objectively measured in the participants.” He says, “We have no idea what is the level of drinks they were actually drinking. That kind of information you can only get in a cohort study with a questionnaire.”6
Lastly, although the study had a very large sample size, it looked at individuals in only one country (making it problematic- selection bias). However, just because people in France drink more than say, people in the US, excessive drinking is still a substantial enough risk for dementia, meaning people need to be aware and take adequate precautions.
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Sources and References

  1. CNN, February 21, 2018.
  2. CNN, February 21, 2018.
  3. CNN, February 21, 2018.
  4. CNN, February 21, 2018.
  5. CNN, February 21, 2018.
  6. CNN, February 21, 2018.