Smoking raises the risk of Alzheimer's disease by 40% — data from a meta-analysis of 2.8 million people

What the researchers found

Scientists from Curtin University in Australia found that smokers have a 40% higher risk of Alzheimer's disease than people who have never smoked. The results were published in the journal eClinicalMedicine. The researchers analyzed data from 61 studies involving about 2.8 million people: smokers overall had a 31% higher risk of dementia, and the likelihood of vascular dementia, which is linked to impaired blood supply to the brain, was 52% higher.

Dependence on the number of cigarettes

The researchers found a dose-dependent effect: people who smoked about 10 cigarettes a day had a 16% higher risk of dementia, while those who smoked 20 cigarettes daily had a 34% higher risk. The key finding concerns quitting smoking: according to the authors, former smokers had a lower risk of dementia than those who continued to smoke, and overall their risk did not differ from that of people who had never smoked. This means that, judging by the meta-analysis data, the link between smoking and dementia is reversible after quitting cigarettes.

Context

Classic dementia involves the death of brain cells and is associated with the accumulation of pathological proteins in tissues — amyloid and tau protein — which destroy neurons. Alzheimer's disease is the most common type of dementia: it accounts for about 60–80% of all cases of cognitive impairment in older people. Vascular dementia arises from strokes, mini-strokes, atherosclerosis, or advanced hypertension. The study's authors note that quitting cigarettes may be important not only for heart and lung health, but also for preserving memory and mental abilities in old age. Earlier, according to Gazeta.Ru, it was reported that a certain type of work reduces the risk of dementia by 18%.