June 3, 2026
Need more incentive to quit smoking? It may substantially reduce your risk of developing Alzheimer’s disease, according to a new report. The study found that stopping smoking even late in life may have benefits for the brain, though weight gain after quitting may mitigate some of those benefits.
Smoking rates have declined in recent decades, down from a high of over 40 percent in the 1960s. Still, about 10 percent of Americans overall still smoke, with higher rates among older Americans, despite well recognized risks like lung cancer, heart disease and strokes.
For the study, researchers looked at 32,802 men and women who were part of the long-running Health and Retirement Study, which is examining the long-term impact of aging on health among a nationally representative sample of older Americans. Their average age at the start of the study was just over 60. None had Alzheimer’s disease or other serious memory problems at the start. About 20 percent were current smokers, 36 percent were former smokers, and 43 percent had never smoked.
Participants were evaluated every two years about their smoking habits and general health. They also underwent regular tests of memory and thinking skills.
Researchers followed them for over two decades. During that time, 5,868 develop Alzheimer’s disease or other form of dementia. After adjusting for risk factors such as age, levels of physical activity and major medical conditions like heart disease and stroke, the researchers found that those who quit smoking had a 16 percent lower risk of dementia that their peers who continued to smoke. The benefits of quitting smoking increased the longer they abstained from smoking, with dementia risk approaching that of those who had never smoked after about seven years.
Weight changes after quitting smoking, however, seemed to influence these benefits. People who gained no to moderate weight, or up to about 11 pounds, after quitting continued to show a lower dementia risk and slower cognitive decline. In contrast, cognitive benefits diminished in those who gained substantial weight, or more than 22 pounds, after quitting. The results were published in Neurology, the medical journal of the American Academy of Neurology.
“People often worry about what happens after they quit smoking, including weight gain,” said study author Hui Chen of 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.”
The researchers caution that many factors influence who ultimately develops Alzheimer’s disease, and that the effects of weight gain and metabolic changes are multifaceted and complex. “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,” Dr. Chen said.
The study showed only an association between quitting smoking and lower dementia risk and cannot prove cause and effect. But the study was large and builds on earlier research showing a link between smoking and Alzheimer’s disease.
Smoking is known to contribute to vascular disease and can damage blood vessels throughout the body, including the brain, depleting the brain of oxygen. Smoking also stokes inflammation, which is increasingly believed to be important in the development of Alzheimer’s disease. In addition, smoking may hasten the build-up of the toxic proteins beta-amyloid and tau that form the telltale brain plaques and tangles of the disease.
“Our findings emphasize the importance of smoking cessation for dementia prevention among smokers,” the authors concluded. “Future research should further explore the mechanisms by which weight gain may influence brain health and investigate potential interventions to support both smoking cessation and weight management in aging populations.”
By ALZinfo.org, The Alzheimer’s Information Site. Reviewed by Eric Schmidt, Ph.D., Fisher Center for Alzheimer’s Research Foundation at The Rockefeller University.
Source: Hui Chen, Jingjing Wang, Sirui Lai, et al: “Smoking Cessation, Weight Change, and Risk of Dementia: A Prospective Cohort Study.” Neurology, May 20, 2026
