Smoking causes thinning of the brain’s cortex, leading to a decline in critical thinking skills, a new study warns.
The cortex is the outer layer of the brain in which critical cognitive functions such as memory, language, and perception take place.
A Canadian and Scottish research team looked at 244 male and 260 female subjects. Their average age was 73, and the group included current smokers, ex-smokers, and non-smokers.
All of the subjects were examined as children in 1947 as part of the Scottish Mental Survey. The researchers used health data gathered during recent personal interviews with the subjects, and also analyzed data from MRI scans showing the current state of the subjects' brain cortices.
Although the cortex grows thinner with normal aging, the study found that current and ex-smokers had many areas of thinner brain cortex than those who never smoked.
Quitting helped, as those who had stopped smoking seemed to partially recover their cortical thickness, but the process was slow and heavy ex-smokers who had kicked the habit more than 25 years ago still had a thinner cortex, the study found.
"Smokers should be informed that cigarettes could hasten the thinning of the brain's cortex, which could lead to cognitive deterioration. Cortical thinning seems to persist for many years after someone stops smoking," said Dr. Sherif Karama, assistant professor at McGill University and the lead author of the study, which appeared in the journal Molecular Psychiatry.
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