A new long‑term study suggests that quitting smoking could have protective benefits for the brain in addition to the well‑known cardiovascular and respiratory gains.

Researchers in China tracked more than 32,000 adults over a span of 25 years and discovered that people who stopped smoking had a lower risk of developing dementia than those who continued.

The findings, published in the journal Neurology, add to a growing body of evidence linking smoking cessation with improved cognitive health as people age.

During the study period, researchers documented 5,868 cases of dementia among participants. Those who quit during the research window showed a significantly reduced risk compared to current smokers.

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Their dementia risk was found to be similar to that of individuals who had quit before the study began and people who had never smoked at all.

The analysis also showed that the likelihood of developing dementia decreased the longer a person remained smoke‑free.

After about seven years without smoking, their risk approached that of lifelong non‑smokers.

The benefits appeared strongest for participants who maintained stable weight or gained little after quitting, suggesting that post‑cessation weight changes may influence outcomes.

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Lead researcher Hui Chen said in a statement, “Our findings suggest that quitting smoking may support long‑term brain health, but they also highlight that what happens after quitting matters.”

Zaid Fadul, a Harvard‑trained physician and chief medical officer of Bespoke Concierge MD who was not involved in the study, said the results reinforce the idea that quitting benefits the brain at nearly any life stage.

“The key takeaway is that the brain appears to benefit from smoking cessation at virtually any stage,” Fadul said.

He explained that smoking contributes to chronic inflammation, oxidative stress, and harm to blood vessels that supply the brain — factors linked with cognitive decline and dementia.

Fadul emphasized that smokers should not feel it is too late to stop. “Importantly, it is rarely ‘too late’ to quit,” he said.

“While earlier cessation offers the greatest benefit, the body and brain begin recovering soon after smoking stops.”

Improved circulation, lower inflammation, and strengthened cardiovascular function may help protect cognitive performance later in life, Fadul added.

“Every year without tobacco is a step toward lowering future dementia risk and improving overall health,” he said.

Still, the researchers noted that the study established an association between quitting smoking and reduced dementia risk, but it did not prove a direct cause‑and‑effect relationship.

Other factors, including general health behaviors and environmental influences, might also have affected the findings, the authors acknowledged.