The Effects of Moderate Drinking on the Brain

Alcohol - Moderate Drinking

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For those of us who enjoy a glass of wine with dinner or a beer or two with friends after work on occasion, research over the last decade handed us a gift with multiple reports suggesting that moderate drinking may have some health benefits by lowering one’s risk of cardiovascular incidents and dementia. But a recent study by Anya Topawala and colleagues in London says not so fast. The rigorously designed longitudinal study, which tracked the alcohol intake and cognitive status of 550 participants over 30 years, found that even moderate drinking was associated with adverse brain outcomes.

Our new briefing paper, “Alcohol and the Brain: Emerging Science Raises Questions About Brain Benefits of Moderate Drinking,” takes note:

One of the most striking findings from the study was the linkage between alcohol use and hippocampal atrophy, a measure of how much shrinkage occurs in this deep-brain structure that is critical to memory functions. Decreased hippocampal volume, especially on the right side, has been identified as a possible preclinical marker of Alzheimer’s disease. In the Topawala study, hippocampal shrinkage in alcohol users was dose-dependent: the more alcohol one drank, the greater the atrophy. While heavy drinkers were at the highest risk compared with abstainers, even those drinking moderately had three times the odds of right-sided hippocampal atrophy. The researchers found no protective effect of light drinking over abstinence.

As with any research, it’s important to know the strengths and weaknesses of a particular type of study. The observational studies on alcohol intake, which include Topawala’s work, can draw between links between behavior and health, but can’t prove causation. From the paper:

Using abstainers as a comparator group raises issues as well, he said. “One of the findings that has been repeated in these kinds of observational studies is that people who drink moderately have better health outcomes than people who are abstinent,” [said Killian Welch, a consultant neuropsychiatrist with the Royal Edinburgh Hospital working for the National Health Service in the United Kingdom]. “That’s been interpreted to imply that alcohol is having some sort of health benefit. While that is one possible explanation, an alternative explanation is that teetotalers [non-drinkers] do worse than moderate drinkers because of other aspects that are likely to affect health outcomes.”

An obvious one, he said, is that abstainers may not drink because they have a history of alcohol dependence, or because they have health conditions or take medications that make them less likely to drink. Any of these could skew results in favor of moderate drinking. Cross-sectional studies that don’t probe life-long drinking habits are going to miss any history of heavy drinking.

So, given the new research, is there a safe amount of alcohol people can consume? Read the complete briefing paper to learn more about UK and US guidelines, and to hear from experts such as Welch and George Koob, director of the National Institute on Alcohol Abuse and Alcoholism.

-Ann L. Whitman

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