It is well known that smoking can cause long-term effects on health and increases the risk of cancer, and cardiovascular diseases. If this still does not deter you from quitting the habit then more ill-effects are at your disposal. According to a study by researchers at Washington University School of Medicine in St. Louis, smoking shrinks the brain. The good news is that quitting smoking prevents further loss of brain tissue — but still, stopping smoking doesn’t restore the brain to its original size. Since people’s brains naturally lose volume with age, smoking effectively causes the brain to age prematurely, the researchers said.

The findings, published in Biological Psychiatry: Global Open Science, help explain why smokers are at high risk of age-related cognitive decline and Alzheimer’s disease.

“Up until recently, scientists have overlooked the effects of smoking on the brain, in part because we were focused on all the terrible effects of smoking on the lungs and the heart,” said senior author Laura J. Bierut, the Alumni Endowed Professor of Psychiatry. “But as we’ve started looking at the brain more closely, it’s become apparent that smoking is also really bad for your brain.”

Scientists have long known that smoking and smaller brain volume are linked, but they’ve never been sure which is the instigator. And there is a third factor to consider: genetics. Both brain size and smoking behavior are heritable. About half of a person’s risk of smoking can be attributed to his or her genes.

“It sounds bad, and it is bad,” Bierut said. “A reduction in brain volume is consistent with increased aging. This is important as our population gets older, because aging and smoking are both risk factors for dementia.”

“You can’t undo the damage that has already been done, but you can avoid causing further damage,” Chang said. “Smoking is a modifiable risk factor. There’s one thing you can change to stop aging your brain and putting yourself at increased risk of dementia, and that’s to quit smoking.”