Smoking cigarettes linked to alarming brain volume loss, prematurely ages brain, study reveals

The research team from the Washington University School of Medicine in St. Louis, who carried out this study, suggests that their findings may contribute to a better understanding of why people who smoke cigarettes often have a higher risk of age-related dementia and Alzheimer's disease.

Laura J. Bierut, a Professor of Psychiatry and a co-author of the study, noted that until recently, the effect of smoking on the brain had not received much attention from scientists, who were more focused on other equally serious effects of nicotine addiction, such as its impact on the lungs and heart. However, when they began to consider the effect on the brain, Bierut observed that smoking is also extremely harmful to this organ.

For the study, Bierut's team utilized data sourced from the UK Biobank, a publicly available database that includes information on the health, lifestyle, and genes of roughly half a million people, predominantly of European ancestry.

The analysis involved 32,094 individuals for whom data on brain volume (based on imaging studies), smoking history, and genetic predisposition to smoke were readily available.

The study found that cigarette smoking is linked with a reduction in brain volume. A person's brain volume diminished more the more they smoked – the correlation between the number of cigarette packs smoked annually and a decrease in brain volume was directly proportional. Cigarette smoking had the most significant impact on the reduction in the volume of grey matter.

The researchers also verified that genetic factors affect the likelihood of someone starting to smoke cigarettes, and consequently, these factors could indirectly contribute to a decrease in brain volume.

"This is indeed alarming. Reduction in brain volume equates to an accelerated brain aging process," stated Bierut. She further noted that while brain volume naturally decreases with age, smoking causes the brain to age prematurely. This is strongly associated with the risk of developing dementia.

The scientists emphasize that the reduction in brain tissue volume seems to be an irreversible process. Upon examining data related to individuals who had quit smoking many years prior, it was observed that their brains remained smaller than those of non-smokers. However, the positive news is that quitting smoking halts further reduction in brain volume.

"While we cannot undo the damage that has already happened, we can prevent further harm. Smoking is a modifiable risk factor. Quitting smoking is one step we can take to stop the brain aging process and to prevent an increased risk of dementia," the study's co-author concluded.