Does Moderate Alcohol Drinking Permanently Harm Our Brains?

Does Moderate Alcohol Drinking Permanently Harm Our Brains?

We know that alcohol consumption can impair brain function. It’s the reason why many governments penalize drunk driving. We might assume, however, that brain function impairment from alcohol consumption is temporary, at least for moderate drinkers of alcohol. A new study published in January 2020 now refutes that assumption.1

Previous studies have established that loss of brain gray and white matter volume accelerates with aging in chronic alcoholics, particularly in the medial-prefrontal and orbitofrontal cortices.2 Another previous study based on only eight adults aged 61 and older found a tentative link between habitual daily consumption of alcohol—not at the level of chronic alcoholics—and brain impairment.3

The latest research study is the first on a large sample of people with accompanying MRI brain scans. A team of five neuroscientists and computational biologists at the University of Southern California (USC) analyzed the brain imaging data collected on 17,308 UK Biobank subjects aged 45 to 81 years. This sample of 17,308 individuals included ethnic diversity and had roughly equal numbers of men and women.

The USC team first developed a metric for relative brain age (RBA). This RBA describes a subject’s brain age relative to his or her peers of the same chronological age, based on whole-brain anatomical measurements from the subject’s MRI brain scans. A positive RBA means that the subject’s MRI brain scan shows that his or her brain has aged more than the average of other people of the same chronological age in the 17,308 UK Biobank sample. The team then “showed that subjects with positive RBA performed worse in various cognitive functions while subjects with negative RBA performed better.”4 Finally, the team looked for correlations of RBA with tobacco smoking, alcohol consumption, and genetic variants.

RBA Correlations
The researchers found that “daily or almost daily consumption of tobacco and alcohol were both significantly associated with increased RBA.”5 Neither of these associations were impacted by age or lifestyle since at all age ranges for the 17,308 subjects, about half had a positive RBA and half had a negative RBA.

Additionally, the paper reports an especially strong correlation with smoking tobacco. Each pack-year of smoking tobacco produces 0.03 years of increased RBA. (A pack-year = smoking the equivalent of one pack of cigarettes per day for a whole year. Two packs a day for a five-year period produced 0.3 years of increased RBA. Half a pack a day for 20 years also produced 0.3 years of increased RBA.)

Unfortunately, the researchers were unable to develop reliable data for alcohol consumption over the subjects’ lifetimes. Nevertheless, they found that for every gram of alcohol consumed a day, the brain aged 0.02 years. The average can of beer or small glass of wine contains 14 grams of alcohol. Therefore, subjects who drank the equivalent of two small glasses of wine per day suffered additional brain aging of 0.56 years or 205 days. The team’s analysis of the 17,308 British subjects showed that quitting smoking or quitting daily alcohol consumption did not reverse the brain damage. Evidently, the induced brain damage is permanent.

The team also found that:

“Pairwise comparisons among groups with different alcohol consumption frequencies showed that the strongest difference was between the group who drank alcohol on most or all days (with an RBA of 0.4 years) and the rest of the alcohol drinking frequency categories (i.e., those who abstained from drinking, drank at special occasions only, 1~3 times a month, 1~2 times a week, or 3~4 times a week), while the difference among groups who didn’t drink on most or all days was insignificant.”6

In other words, drinking the equivalent of three small glasses of wine per week or less showed no significantly measured increased RBA but drinking alcohol daily, or almost daily, did.

Researchers also observed a genetic factor associated with structured brain aging. Increased RBA correlates with mutations in the MAPT gene. MAPT codes for tau protein. Previous studies showed that mutations in the MAPT gene are associated with the onset of dementia and Parkinson’s disease.7 The researchers concluded that it is highly likely that the MAPT gene is a functional gene for restraining the aging of the human brain.

The paper closes with recommendations for further study. They encourage studies on other large population samples (10,000+ individuals) using different ethnic groups, different age ranges, and different lifestyle practices. They especially called for studies to determine whether the brain aging induced by alcohol consumption is accumulative like it is for smoking tobacco—that is, whether or not the total amount of alcohol consumed in one’s lifetime is a strong factor for increased RBA.

How Should We Then Live?
The USC team’s analysis affirms that any amount of tobacco smoking harms the brain, not to mention the lungs and other body organs. Hence, we would all be wise to avoid smoking tobacco.

Moreover, the research provides some support for the Bible’s teachings on and depictions of alcohol consumption. Many Bible passages strongly prohibit drunkenness, inebriation, and habitual drinking of alcoholic beverages (e.g., Proverbs 23:20, 31, Proverbs 31:4–7, Isaiah 5:11, Galatians 5:19–20, and Ephesians 5:18). On the other hand, several scriptural texts condone occasional drinking of wine (e.g., Psalm 104:14–15, Ecclesiastes 9:7, Matthew 15:11, and 1 Timothy 5:23). Most notably, Jesus includes wine in the sacrament of communion and in his first miracle of changing water to wine for a wedding.

Certainly, the analysis demonstrates that using wine in contemporary communion practice is almost always as safe as using grape juice. Drinking a thimble full of wine once or twice a week has no measurable scientific difference over drinking the same quantity of grape juice. Hence, for such communion practices there is no scientific basis for believers to allow one drink choice and not the other.

I used the qualification “almost always” for a reason. I know of a few churches where the priest drinks a five-ounce cup of wine at every communion service he officiates. With more than one such communion service per day that priest is experiencing substantially increased RBA. During the American prohibition era (1920–1933) many churches took advantage of the communion exception in the law to evolve their communion cups from thimble-sized to large cups and to inaugurate daily communion services. At a home Bible study I taught decades ago, a young man consistently arrived inebriated. When I questioned him, he told me he never drank more than two glasses of wine per day and only for communion purposes. When I asked him about the size of his communion glasses, he admitted that the glasses held in excess of 12 ounces of wine.

The team’s analysis implies that redefinitions of “drinking in moderation” or “drink alcohol only in moderation” are in order. My Healthfinder, a US government website, defines a moderate amount of alcohol consumption as “up to 1 drink in a day for women” and “up to 2 drinks in a day for men” where 1 drink is defined as (1) a 12-ounce bottle of regular beer, (2) a 5-ounce glass of wine, or (3) a 1.5-ounce shot of hard liquor.8 The research findings of the USC scientists show that these standards for “drinking in moderation” need to be reduced by at least a factor of three. Their results seem consistent with what the Bible teaches about a lifestyle of wisdom, moderation, and care for other human beings.

  1. Kaieda Ning et al., “Association of Relative Brain Age with Tobacco Smoking, Alcohol Consumption, and Genetic Variants,” Nature Scientific Reports 10 (January 30, 2020): id. 10, doi: 10.1038/s41598-019-56089-4.
  2. Adolf Pfefferbaum et al., “Brain Grey and White Matter Volume Loss Accelerates with Aging in Chronic Alcoholics: A Quantitative MRI Study,” Alcoholism: Clinical and Experimental Research 16, no. 6 (December 1992): 1078–89, doi: 10.1111/j.1530-0277.1992.tb00702.x; Samuel Asensio et al., “Magnetic Resonance Imaging Structural Alterations in Brain of Alcohol Abusers and Its Association with Impulsivity,” Addiction Biology 21, no. 4 (July 2016): 962–71, doi: 10.1111/adb.12257.
  3. Mohit Rana et al., “Real-Time fMRI in Neuroscience Research and Its Use in Studying the Aging Brain,” Frontiers in Aging Neuroscience 8 (October 18, 2016): id. 239, doi: 10.3389/fnagi.2016.00239.
  4. Ning et al., “Association of Relative Brain Age,” 5.
  5. Ning et al., 1.
  6. Ning et al., 3–4.
  7. Michel Goedert, “Alzheimer’s and Parkinson’s Diseases: The Prion Concept in Relation to Assembled Aβ, Tau, and α-Synuclein,” Science 349, no. 6248 (August 7, 2015): id. 1255555, doi:10.1126/science.1255555.
  8. “Drink Alcohol Only in Moderation,” MyHealthfinder (website), US Department of Health and Human Services, last visited May 21, 2019, Their latest website update is to commended, however, for pointing out that the consumption of too much alcohol, just like the consumption of too many refined sugars, contributes to unhealthful weight gains.