Alcohol is one of the most widely used and abused drugs on the planet. It’s important for us to understand how it is, or is not, affecting our bodies and our health. There are countless studies linking alcohol and health – from how a small amount of red wine may be good for your heart, to how moderate drinking may help protect against dementia – but the problem is that correlation doesn’t always imply causation.
As a PhD student, I wondered, could I test the popular claim that moderate alcohol use shrinks people’s brains?
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First, my colleagues and I examined a group of over 1,300 college-aged adults and found several parts of the brain that were smaller in people who drank more. I then conducted an analysis on a second data set with adult twins and their siblings (over 800 of them), looking at alcohol consumption and brain volume, and did not find any evidence of a causal effect.
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This, and some other analyses, suggested that there are separate genetic factors that drive both reduced brain volume and increased alcohol consumption.
Moderate alcohol consumption, it turns out, doesn’t shrink people’s brains. Instead, people with brains that are a little smaller than average in a couple places are likely to drink slightly more than people with average sized-brains.
