A study of more than 30,000 people shows that one can of beer a day is enough to make your brain smaller!

Alcohol consumption is one of the leading causes of death, disability and disease burden worldwide. Long-term excessive drinking can cause liver damage, gout, colorectal cancer, breast cancer, and increased risk of cardiovascular disease. Its damage to the nervous system should not be underestimated, and is manifested in: memory loss, reduced executive control ability, decision-making disorders, cognitive impairment, etc.

"Excessive drinking is harmful to health" has become a consensus, however most people's views on moderate drinking are still ambiguous. The dietary guidelines of some countries, such as China and the United States, recommend avoiding drinking, or even drinking in moderation. However, in some Mediterranean countries, considering the protective effect of red wine on the cardiovascular system, the view that moderate drinking is good for health is proposed.

Recently, a large-scale population survey study from the University of Pennsylvania showed that even moderate drinking can make our brains smaller, and the more we drink, the more obvious the changes in brain volume are. The study was published in Nature Communications on March 4.

The study included a sample of 36,678 healthy people aged 40-69 years. Questionnaires recorded the participants' alcohol consumption and brain magnetic resonance imaging was collected to calculate the gray matter and white matter volume in different areas of the brain.

After controlling for a variety of variables, including participants' age, height, handedness, gender, smoking status, socioeconomic status, race, and where they lived, the researchers found that:

Consuming 0-1 unit of alcohol per day did not have much effect on brain volume; however, consuming 1-2 units of alcohol per day reduced the volume of gray matter and white matter by 0.127 and 0.074 standard deviations, respectively; and consuming 2-3 units of alcohol per day reduced the volume of gray matter and white matter by 0.223 and 1.28 standard deviations, respectively (compared to 1-2 units of alcohol, the reduction was 75% higher).

Note: 1 alcohol unit = 8g ethanol, which is equivalent to 312.5ml of beer with an alcohol content of 3.2%. Alcohol content ≠ malt juice content. The alcohol content of the more common beer on the market is 3.2%.

This also means that there is not a linear relationship between alcohol consumption and reduction in brain volume, but an exponential relationship. The more you drink, the greater the impact on the brain. Even after removing the highest drinking group in the population, the conclusion still holds true.

Moreover, the reduction in brain volume caused by drinking is not limited to a certain area of ​​the brain, but widely affects multiple brain regions, including the frontal lobe, parietal lobe, insula, temporal lobe and cingulate gyrus.

Figure 1: Relationship between daily alcohol consumption and standard gray matter volume and standard white matter volume

Under normal circumstances, brain volume decreases with age, but some patients with neurodegenerative diseases, such as Parkinson's disease and Alzheimer's disease, experience more severe brain atrophy. Diffuse brain atrophy is also associated with memory impairment, cognitive impairment, intellectual decline, and personality changes.

If the reduction in brain volume caused by drinking is compared with the brain atrophy caused by aging, compared with people who do not drink, those who consume 1 unit of alcohol per day will age their brain 0.5 years earlier; while those who consume 4 units of alcohol per day will age their brain a full 10 years earlier.

The number of years of premature brain aging is also exponentially related to the amount of alcohol consumed per day, meaning that the last drink may have a greater impact than any of the previous ones, so drinking one less drink is more meaningful for those who drink the most.

From this study, we can conclude that 8 grams of alcohol per day is enough to change our brains. A 330 ml can of beer can easily reach this critical point. If the average daily intake of drinkers in my country is 30 grams (3.75 alcohol units) for men and 12.3 grams (1.5375 alcohol units) for women, it can be said that for a person with a drinking habit to control daily alcohol intake below 8 grams is about the same difficulty as not drinking.

Therefore, there is no such thing as moderation when it comes to alcohol. For the sake of health, the best practice is not to drink at all.

References

[1] Daviet R, Aydogan G, Jagannathan K, Spilka N, Koellinger PD, Kranzler HR, Nave G, Wetherill RR. Associations between alcohol consumption and gray and white matter volumes in the UK Biobank. Nat Commun. 2022 Mar 4;13(1):1175. doi: 10.1038/s41467-022-28735-5. PMID: 35246521.

[2] Scientific Research Report on Dietary Guidelines for Chinese Residents (2021)