Smoking cigarettes damages multiple organs, including the brain, possibly explaining why as many as 14 percent of Alzheimer’s cases worldwide are linked to smoking. A new study shows that cigarette smoking reduces brain volume, accelerating normal brain aging.

Researchers investigated the relationship between smoking and brain volume in more than 32,000 adults enrolled in the UK Biobank study. They used a set of guidelines (called Bradford Hill’s criteria) to determine whether a potential cause-and-effect relationship exists between a specific factor (such as smoking) and a health outcome (such as a disease). They also investigated whether genetic factors predispose some people to initiate smoking.

They found that regular smoking, especially heavier smoking, was linked to notable brain shrinkage, especially in terms of total gray matter volume. The more years a person smoked, the greater the shrinkage. They also found that daily smoking played a role in the relationship between the genetic risk score for smoking initiation and the total gray matter volume.

These findings suggest that smoking cigarettes reduces drives brain volume losses, effectively aging the brain prematurely. They also align with other research demonstrating that regular (daily or nearly daily) cigarette smoking increases relative brain aging, driving poor cognitive function and declines in fluid intelligence. Many habits like smoking (and overeating) can be broken using mindfulness techniques. Learn more in this clip featuring Dr. Ashley Mason.

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