Smoking Doesn't Just Hurt Your Body — It Also Hurts Your Brain

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Add this to the rap sheet of smoking cigarettes: The longtime foe of optimal health may not only be hurting our bodies, but going after our brains as well.

A new study published in the scientific journal Molecular Psychiatry suggests that smoking cigarettes physically taxes the brain by breaking down the cortex, its outer layer, over time. The cortex plays a role in how we think, solve mathematical problems, stay attentive, and even learn languages.

The science: Your brain's cortex naturally thins as you get older, but smoking may speed that process up. Though past studies have linked smoking to a loss of mental acuity, this is one of the first to delve into how it might change the actual structure of the brain.

"If you had a choice between affecting your cortex and not affecting your cortex, I would choose not affecting it," Dr. Sherif Karama, a psychiatrist at McGill University in Canada who led the observational study, told Mic.

The research indicates that even though the thinning effect may be reversible, it can take anywhere from a few weeks after a person quits smoking to 25 years, depending on how much a person has smoked over their lifetime.

"One of the surprises was how widespread the effect was," Karama said. The thinning affected large portions of the brain, he explained, not just isolated spots.

The yellow portions of the brain show the spots where people who never smoked had a thicker cortex than than people who were current smokers  Molecular Psychiatry/Karama et al.
The orange and yellow shows the regions where ex smokers have a thicker cortex than their current smokers in the study do.  Molecular Psychiatry/Karama et al
The orange parts of the image show parts of the brain where non-smokers had a thicker cortex than ex-smokers  Molecular Psychiatry/Karama et al

The study: The researchers took advantage of a large dataset that came from the 1947 Scottish Mental Survey, a government initiative with the goal of testing the cognitive ability of children over time. By recruiting 504 men and women (smokers, ex-smokers and non-smokers) who participated in the survey as children, the researchers could paint a better picture of how smoking might have affected their brain as adults. The team then interviewed each adult to test their cognitive ability once again, and collected brain scans to analyze and compare.

There was a very distinct pattern in the pictures. 

"What we have observed is that in old age, the current smokers had the thinnest cortex, those that never smoked had the thickest cortex, and ex -smokers were in between these two groups in terms of thickness. This was interpreted as suggesting accelerated thinning," said Karama.

The researchers don't know exactly why this happens but they do have a few hunches. One theory is that because smoking affects our lung capacity, it slows down how much oxygen gets to the brain, which might explain the cognitive decline and thinner cortex.

Another theory asks the age-old question: Which came first, the chicken or the egg? Perhaps people who develop a smoking habit may naturally have a thinner cortex to begin with. If that's the case, then developing an extremely thin cortex around the brain might predate smoking rather than follow it, the researchers explain in their study.

Source: Uncredited/AP


Why this matters: Karama notes that one of the tricky parts about getting a smoker to quit is convincing them why it's important. Another reason is the length of time it takes before the negative side effects of smoking start to become apparent to the average smoker.

In Canada, the government has gone to gruesome lengths to dissuade smokers, even printing diseased and tumorous lungs on packages, but the efforts seem to be futile. Even in the U.S., ad campaigns have taken to shaming celebrities into giving up the habit by spreading photos of them in the act. But since the negative effects of smoking often set in later in life smokers tend to carry the attitude of "smoke now, worry later."

Even though the study is observational, the researchers were meticulous in their data collection and analysis. Even just the possibility that stopping could reverse smoking-related-thinning should serve as a strong incentive for a smoker to quit.

Just something to think about on your next smoke break.