• Posted May 22, 2026

Quitting Smoking Might Lower Your Dementia Risk

Quitting smoking might protect your future brain health, a new study says.

People who quit smoking had a lower risk of developing dementia, especially if they didn’t gain excess weight afterward, researchers reported May 20 in the journal Neurology.

“People often worry about what happens after they quit smoking — including weight gain and associated metabolic changes,” said lead researcher Hui Chen, dean of psychological and behavioral sciences at Zhejiang University School of Medicine in Hangzhou, China.

“What we found is that quitting is still associated with better brain outcomes but maintaining your weight may help preserve those benefits,” Chen said in a news release.

For the study, researchers tracked nearly 33,000 middle-aged and older U.S. adults without dementia for an average of 10 years. About 20% were current smokers, 36% were past smokers and 43% had never smoked.

Participants were interviewed roughly every two years about their smoking status, weight and health. They also took regular memory and thinking tests to track their brain health.

During the study, nearly 5,900 people developed dementia.

People still smoking developed dementia at a rate of 1.5 cases per 100,000 person-years, compared to 1.6 cases per 100,000 person-years for those who quit during the study. Person-years represent the amount of time each participant spent in the study as well as the number of people in the study.

Overall, people who quit smoking had a 16% lower risk of dementia compared with those who kept smoking, researchers found.

The benefit gained from quitting increased over time, such that people who’d stopped smoking about seven years ago had a similar dementia risk to that of people who never smoked, results showed.

However, weight changes that occurred after quitting influenced this brain benefit, researchers found.

People who gained 11 pounds or less after they stopped smoking continued to show a lower dementia risk, the study said. However, people who gained 22 pounds or more did not experience this reduced risk.

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

“Future research is needed to better understand how weight management and other lifestyle factors can help people maximize the cognitive benefits of quitting smoking as they age,” Chen added.

More information

The American Lung Association has more on the benefits of quitting smoking.

SOURCE: American Academy of Neurology, news release, May 20, 2026