A new cohort study has found that smoking can shrink the brain, and genes might play a big role in a person’s likelihood to smoke. Scientists at Washington University School of Medicine in the US discovered that smoking doesn’t just harm the lungs and heart but can also age the brain faster. They found that smokers are more vulnerable to age-related memory decline and Alzheimer’s disease, a condition that affects the brain and worsens as people grow older.
“Until recently, we focused on how smoking affects the lungs and heart, ignoring its impact on the brain,” explained Laura J. Bierut, a psychiatry professor and the study’s senior author, published in the journal Biological Psychiatry: Global Open Science. “But now, as we examine the brain more closely, it’s evident that smoking is really harmful to it.”
The researchers emphasized that quitting smoking can prevent further damage to the brain, although it cannot fully reverse the shrinkage caused by smoking.
Previous studies have suggested a link between brain size and smoking behavior being inherited.
In this new research, scientists aimed to better understand how genes, brains, and smoking habits are connected.
They studied data from the UK Biobank, a large biomedical database containing information on half a million people, primarily of European descent. The team analyzed brain imaging data, smoking habits, and genetic information from 32,094 individuals.
The findings revealed a strong connection between smoking habits, genetic predisposition to smoking, and brain volume. People who smoked more tended to have smaller brain volumes. Interestingly, when examining all three factors together, the association between genetic predisposition to smoking and brain volume disappeared.
The researchers concluded that genetic risk influences smoking behavior, leading to reduced brain volume. This reduction in brain size aligns with accelerated aging, making smokers more prone to dementia, particularly as the population ages.
Moreover, the study highlighted that even after years of quitting smoking, the brain’s shrinkage caused by smoking remained irreversible in individuals. Their brains were consistently smaller compared to those who never smoked.
“This finding underscores the importance of addressing smoking as a risk factor for both aging and cognitive decline in our aging population,” said Bierut.”