Researchers looked at the consequences of tobacco use at the brain level, and their findings help explain why smokers are at high risk of age-related cognitive decline and Alzheimer’s disease, according to an article in Biological Psychiatry: Global Open Science.

With the aim of unraveling the relationship between genetics, brain and behavior, the authors of the research analyzed data extracted from the UK Biobank, on the health and behavior of half a million people, mostly of European descent.

The team analyzed de-identified data on brain volume, smoking history and genetic risk of smoking from 32,094 people.

They were able to show that each pair of factors were related: smoking history and brain volume; genetic risk of smoking and history of smoking; and genetic risk of smoking and brain volume. Furthermore, the association between smoking and brain volume was dose-dependent: the more packs a person smoked per day, the smaller their brain volume.

When all three factors were considered together, the association between genetic risk for smoking and brain volume disappeared, while the link between each of them and smoking behaviors remained.

Using a statistical approach known as mediation analysis, the researchers determined the sequence of events: genetic predisposition leads to smoking, which leads to a decrease in brain volume.

ef/lam/lpn