- A new study suggests that quitting smoking may be associated with a lower risk of dementia and slower cognitive decline over time.
- The researchers found that the participants who quit smoking had a 16% lower risk of dementia compared with people who continued smoking.
- The cognitive benefits of quitting smoking were strongest among people who gained little or no weight after quitting.
Quitting smoking cigarettes can reduce the risk of many health conditions, including cancer, heart disease, and stroke. A new study suggests that smoking cessation may also support long-term brain health.
The study followed more than 32,000 adults in the United States for up to 25 years to examine the connection between smoking habits, post-cessation weight changes, and cognitive health.
The researchers found an association between smoking cessation and a lower risk of developing dementia. They also found that these people experienced slower rates of cognitive decline compared with people who continued smoking.
Smoking rates in the U.S. have steadily declined over the past several decades as more research on the health issues it can contribute to, such as heart disease and lung cancer, has come out. According to the American Lung Association, smoking rates dropped below 10% in 2024.
Researchers are interested in how smoking can affect brain health. For example, a recent study suggests that smoking may contribute to cognitive decline through oxidative stress.
A new long-term study adds to this by looking at the potential cognitive impacts of smoking cessation.
The researchers analyzed data from the Health and Retirement Study, a large-scale study of U.S. adults aged 50 and above. The analysis included 32,802 adults who did not have dementia at the beginning of the study.
The study followed the participants between 1995 and 2020, with a median follow-up period of nearly 10 years. During that time, they completed interviews every 2 years about their smoking habits, body weight, lifestyle behaviors, and medical history.
The researchers grouped participants into three categories:
- current smokers
- former smokers
- never-smokers.
They considered participants who reported smoking during one interview but not the next to have quit smoking during the study period.
The scientists also tracked weight changes after quitting smoking, ranging from no weight gain to a gain exceeding about 22 pounds.
To measure cognitive health, the researchers used assessments that evaluated skills such as word recall, counting backward, and serial subtraction.
By the end of the study, nearly 6,000 participants had developed dementia.
Compared with people who kept smoking, participants who quit smoking during the study had a 16% lower risk of dementia.
People who quit smoking before the study began also had lower dementia risk, as did people who had never smoked.
The researchers found that the benefits of quitting appeared to increase over time. Dementia risk gradually declined the longer people remained smoke-free, approaching the level seen in never-smokers after about 7 years of smoking cessation.
“In our study, the benefits appeared stronger with longer time since quitting,” lead study author Hui Chen, PhD, Zhejiang University School of Medicine, told Medical News Today. “The practical message is: quit smoking, stay physically active, eat well, and manage cardiovascular and metabolic health.”
The study also examined how weight gain after quitting smoking affected these outcomes.
Participants who gained little or no weight after quitting appeared to experience the greatest cognitive benefits.
People who gained up to about 11 pounds still showed a significantly lower dementia risk and slower cognitive decline compared with people who continued smoking.
The participants who gained more than 22 pounds after quitting smoking, however, did not appear to have any cognitive benefits.
“Our study suggests that people who quit, overall, had lower dementia risk and slower cognitive decline than those who continued smoking, so quitting smoking should remain the priority,” Chen said.
“Some weight gain after quitting is common and should not discourage cessation,” he continued. “However, preventing excessive weight gain may help preserve the long-term brain-health benefits of quitting.”
Chen noted that smoking likely affects the brain through multiple pathways, including vascular damage, inflammation, and oxidative stress.
Dung Trinh, MD, an internist at MemorialCare Medical Group and chief medical officer of the Healthy Brain Clinic, told MNT that the findings reinforce the importance of smoking cessation for long-term brain health.
“What stands out most is that smoking cessation was associated with a reduction in dementia risk, but the benefit was not uniform,” Trinh, who was not involved in the current study, said.
He noted that people who quit smoking and gained little or no weight appeared to preserve the cognitive benefit, while those with substantial weight gain did not show the same reduction in dementia risk.
“The practical takeaway is clear: quit smoking, stay quit, and pair cessation with healthy weight and metabolic management,” Trinh suggested.
Anoop Singh, MD, a board-certified psychiatrist from Mindpath Health, said the study offers a hopeful message about the potential brain-health benefits of quitting smoking.
“What stands out most is the hopeful message that quitting smoking may benefit not only the heart and lungs, but also long-term brain health,” Singh, who was likewise not involved in this research, told us.
He noted that the study found lower dementia risk among people who quit smoking, especially with only modest weight gain after quitting.
Singh emphasized that concerns about weight gain should not discourage people from quitting smoking.
“Some weight gain can happen and should not be seen as failure,” he said. “The goal is to combine smoking cessation with steady habits: regular movement, good sleep, stress management, balanced meals, and appropriate medical or behavioral support.”
– Anoop Singh, MD
