Wang Jimin
Wang Jimin
[New Sancai Compilation and First Release] Smoking shrinks the brain, and when brain mass disappears, it's gone forever, a new study suggests.
Brain scans of more than 32,000 people show that a history of smoking is strongly associated with a gradual loss of brain volume. In fact, researchers found that the more cigarettes a person smoked per day, the smaller their brain size became.
The study also identified a potential cascade of events that lead to smoking-related brain loss, with a genetic predisposition to smoking culminating in reduced brain volume.
"It sounds bad, and it is," said senior study author Laura Bierut, a professor of psychiatry at Washington University School of Medicine in St. Louis. "Reduced brain volume is consistent with increased aging. This is important as the population ages, as both aging and smoking are risk factors for dementia."
Research recently published in the journal Biopsychiatry: Global Open Science helps explain previous research that found smokers are at higher risk of depression, age-related brain decline and Alzheimer's disease.
"Until recently, scientists have ignored the effects of smoking on the brain, in part because we focused on all the terrible effects smoking has on the lungs and heart," Bierut said. "But when we started looking more closely at the brain, we found that smoking is really harmful to the brain as well."
Scientists have long known there is a link between smoking and smaller brain sizes, but they have been unable to establish a cause-and-effect relationship.
There is a third factor─heredity. Brain size and smoking behavior are influenced by genetics; in fact, about half of a person's risk of smoking can be attributed to their genes.
To tease out the relationship, Bierut and her colleagues analyzed the smoking histories, genetic data and brain scans of more than 32,000 people as part of a large UK database of half a million people.
The analysis showed that a person's genetic predisposition leads to smoking, which in turn causes a decrease in brain volume. The shrinkage appears to be irreversible. Data shows that people who quit smoking years ago consistently have smaller brains than people who never smoked.
"You can't undo the damage that's been done, but you can prevent further harm," said lead researcher Yoonhoo Chang, a graduate student at the University of Washington. "Smoking is a modifiable risk factor. One thing you can change to stop your brain from aging and increasing your risk of dementia is to quit smoking."
(Compiled by: Wang Jimin)
(Editor: Jiang Qiming)
(Source of the article: First published by Xinsancai)
