Smoking and dementia: People who stop smoking in middle age can slow cognitive decline so markedly that within 10 years their risk of developing dementia approaches that of never-smokers, according to a multinational study published in The Lancet Healthy Longevity.
Researchers from University College London analysed data from 9,436 adults aged 40+ across England, the United States and 10 European countries. Compared with those who continued smoking, participants who quit saw the rate of decline in verbal fluency halve, while memory loss slowed by about 20% over a six-year follow-up.
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“Our study suggests that quitting smoking may help people maintain better cognitive health over the long term, even when we are in our 50s or older when we quit,” said lead author Dr Mikaela Bloomberg. “It seems that for our cognitive health, too, it is never too late to quit.”
At baseline, cognitive performance was similar between those who would quit and those who continued to smoke. Over time, however, quitters showed “more favourable trajectories” on cognitive measures, the authors reported. While the observational design cannot prove causation, the team said the findings offer “compelling motivation” for older adults to stop smoking.
Experts say the results reinforce guidance that lifestyle changes can protect brain health. “Quitting smoking, keeping physically active, eating a balanced diet and drinking less alcohol can all help reduce dementia risk,” said Dr Richard Oakley of the Alzheimer’s Society, noting smoking is among 14 modifiable risk factors identified by dementia researchers.
Scientists believe smoking accelerates neurodegeneration by damaging blood vessels that supply the brain, driving chronic inflammation and causing oxidative stress that can harm neurons. Some researchers cautioned that socioeconomic differences and alcohol use could partly explain the observed gaps, but agreed that the benefits of cessation remain clear.
