Had Enough? How Moderate Drinking Is Bad For Brain

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It’s enough to leave you crying into your pint! Moderate drinking is not as harmless as it seems. In fact it impacts the structure of your brain in a very bad way indeed.

Your Brain On Alcohol

Killjoy researchers from the University of Oxford and University College London studied how alcohol levels affect brain health over a period of thirty years.  Five hundred and fifty people were recruited for the study, none of whom were deemed to be alcohol dependent.

The test subjects completed five cognitive tests over the thirty years. These tests included a lexical fluency test (how many words beginning with a specific letter can you think of in one minute), a semantic fluency test (how many words from a particular category can you think of in one minute) as well as a short term memory test (how many words can you remember from a list of twenty). At the end of the study the participants had MRI scans to see the structure of their brains.

The researchers found that alcohol consumption may cause brain damage at levels previously thought to be safe, or even beneficial. The MRI scans showed that grey matter levels were lower in those that drank, particularly in the right hand side of the hippocampus.This reduction in size, or atrophy, is not good news.

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The hippocampus is where we encode long-term memories and it also processes emotional responses. Worryingly, a damaged or shrunken hippocampus can be  seen in people with dementia and depression.

The Proof Is In The Shot Glass

At several points over the 30 years, participants self-reported how much they drank on average per week. They were then grouped into four categories:

  1. Abstainers – those drank at most one unit per week
  2. Light Drinkers – those that drank less than 7 units per week
  3. Moderate Drinkers – who drank between 14 and 21 units per week
  4. Heavy Drinkers – those that drank more than 30 units per week.

An alcoholic unit is the unit of measurement in the UK. It’s 7g of alcohol. This is equal to 35ml of spirits, a small glass of 12.5% wine or a half-pint of normal strength beer.To help visualize, 14 units per week would be roughly equal to 4 pints (568ml) of beer at 5.2 % strength or 5 large glasses (175ml) of 14% wine.

The good news is that total abstinence is not necessary, light drinkers share the same risk of atrophy in the right side of the hippocampus. Unfortunately, moderate drinkers have three times the risk of hippocampal atrophy. Predictably, heavy drinkers have an even greater risk, as well as greater risks of grey matter shrinkage in other areas.

The brain’s white matter, or communications network, also suffered. The more people drank, the worse the damage. Moderate drinkers also got worse at the lexical fluency test, they could think of 14% fewer words that began with a letter compared to light drinkers and abstainers.

“Higher alcohol use was associated with reduced grey matter density, hippocampal atrophy, and reduced white matter microstructural integrity,” Topiwala et al.

Do I Need To Go Teetotal?

Previous studies on alcohol and brain health yielded mixed results. However, there is a growing body of research that indicates that alcohol is worse for you than we thought. In 2012 a study in rats found that moderate drinking nearly halved the amount of new neurons that were created in the hippocampus.

In 2016 the UK’s guidance on alcohol consumption reduced from a maximum of 21 to 14 units per week for both men and women. In Ireland and the US alcohol are measured by the standard drink measure. A standard drink is 10 grams of alcohol. In Ireland the advice is for up to 11 standard drinks per week for women and 17 for men. The US advises a maximum of 7 standard drinks for women and 14 standard drinks for men. Both the Irish and US advice allow for more alcohol consumption in the moderate drinking range.

The authors of the study acknowledge that it has shortcomings. People tend to underestimate how much they drink, so maybe the effects on the brain happen at higher levels of alcohol consumption. But the reverse also applies; we’re as likely to think our drinking is light or moderate when it is not!

Also, the study was an observational one. This means that we can’t say for sure that it is the alcohol that is causing the effects even though the authors tried to account for every common factor.

But alcohol is a known carcinogen. It raises your lifetime risk of developing many types of cancer. So it’s probably a good thing to cut down.

What To Take Away

Here is a sobering thought. Normal aging decreases the size of your hippocampus by 0.02%. A weekly drink reduces it by 0.01%. So every additional habitual drink ages your brain by six months!

Try to aim for a maximum of seven units per week. Spread those units over a few days and leave some alcohol-free days too. That’s about two pints of craft beer or 2.5 glasses of wine a week, so savour it!

Further reading: Exercise boosts grey matter, reduces Alzheimer’s risk


  • theBMJ – Moderate alcohol consumption as risk factor for adverse brain outcomes and cognitive decline: longitudinal cohort study

  • STAT – Even moderate drinking may speed brain decline

  • DrinkAware -What is a standard drink?
  • Wikipedia – Standard Drink

Had Enough? How Moderate Drinking Is Bad For Brain
Article Name
Had Enough? How Moderate Drinking Is Bad For Brain
Well that sucks! New research shows that even moderate drinking can have negative effects on your brain. What does this mean and how much is too much?
Dermot Barry
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