Researchers at Washington University School of Medicine in St. Louis reveals that smoking is likely associated with a reduction in brain size. The study, published in Biological Psychiatry: Global Open Science, highlights that while quitting smoking can prevent further loss of brain tissue, it doesn't restore the brain to its original size. Smoking appears to accelerate brain aging, contributing to an increased risk of age-related cognitive decline and Alzheimer's disease.
Senior author Dr. Laura J. Bierut notes, “Smoking has been overlooked in relation to its effects on the brain, as the focus was often on its impact on the lungs and heart. However, closer examination shows that smoking is also detrimental to the brain.”
Although the connection between smoking and smaller brain volume has been recognized, distinguishing the instigator has been challenging. Genetic factors, influencing both brain size and smoking behavior, further complicate the relationship. To untangle these complexities, the researchers analyzed data from over 40,000 participants in the UK Biobank, uncovering links between smoking history, genetic risk for smoking, and brain volume.
The study indicates a dose-dependent association, revealing that individuals who smoked more packs per day exhibited smaller brain volumes. When considering all three factors—genetic risk for smoking, smoking behaviors, and brain volume—the researchers found that genetic predisposition leads to smoking, subsequently resulting in decreased brain volume.
Dr. Bierut emphasizes the significance of these findings, stating, “Reduced brain volume aligns with accelerated aging, which is critical as our population ages, given that both aging and smoking are risk factors for dementia.” Unfortunately, the study suggests that the observed brain shrinkage is irreversible, even among those who quit smoking years before.
Lead author Yoonhoo Chang underscores the importance of smoking cessation: “While you can't undo past damage, you can prevent further harm. Smoking is a modifiable risk factor, offering a tangible action to mitigate the aging of the brain and reduce the risk of dementia.”