The key facts

  • Smokers have a 31% higher risk of dementia than people who have never smoked; for Alzheimer's disease it is 40%, and for vascular dementia 52%
  • The risk is dose-dependent: 10 cigarettes a day means a 16% increase, 20 cigarettes a 34% increase
  • No elevated dementia risk was found among former smokers; a causal link has not yet been proven

What the review found

A review of scientific evidence covering about 2.8 million people has linked smoking to an increased risk of dementia, Alzheimer's disease, and vascular dementia. The study, led by researchers at Curtin University in Australia, was published in the journal eClinicalMedicine. According to its findings, smokers have a 31% higher risk of developing dementia than people who have never smoked; for Alzheimer's disease the figure reaches 40%, and for vascular dementia it is 52%.

Risk depends on the number of cigarettes

The authors found a relationship between the number of cigarettes smoked per day and the likelihood of developing dementia: those who smoke 10 cigarettes a day have a 16% higher risk, and those who smoke 20 cigarettes a day have a 34% higher risk compared with people who have never smoked. Study lead Mario Cerfo noted that the link between smoking and dementia grows stronger as cigarette consumption increases, and stressed the need to take into account the effects of smoking on brain health alongside the well-known risks to the heart, lungs, and the likelihood of developing cancer.

Former smokers and limitations of the findings

According to the review, people who quit smoking showed no increased risk of dementia compared with those who never smoked, and their risk was lower than that of continuing smokers. However, the researchers explicitly cautioned that the results do not prove a direct causal link between smoking and dementia, although they add to the arguments that quitting smoking may reduce the risk. Co-author Blossom Stephan called for including brain health in discussions of the risks of smoking and the benefits of quitting.

The authors' recommendations

The researchers recommended expanding anti-smoking campaigns to warn not only about the risks to the heart, lungs, and of cancer, but also about the effects of smoking on brain function and cognitive abilities. They proposed placing brain health warnings on cigarette packs and including them in smoking cessation programs. In addition, the authors called for further research to determine whether the timing of quitting smoking and the length of abstinence affect the level of dementia risk.