Does Quitting Smoking Lower Dementia Risk? What a Study of 32,802 Older Adults Found

Anyone who has tried to stop smoking knows it is rarely a single decision. It is a run of small ones, made over weeks or months, often with a few false starts along the way. People who try again after a slip deserve credit, not criticism.

A study published in the journal Neurology in May is getting fresh attention this month. It asks whether stopping smoking, even in midlife or later, is linked to a lower chance of developing dementia, and how long it might take for any such link to show.

Does quitting smoking lower your dementia risk?

Possibly, but so far the evidence shows an association, not proof. Smoking is widely listed among the risk factors for dementia that people can do something about. Researchers often point to blood vessels: what is good for the vessels of the heart tends to be good for those of the brain. In this study, people who quit had a lower risk than people who kept smoking, and the gap grew the longer they stayed smoke-free. But nobody was asked to quit; the participants were simply followed over time. The study therefore cannot show that quitting itself caused the lower risk. It is encouraging news for anyone thinking about stopping, not a guarantee.

What the researchers did

The work was led by Hui Chen of the Zhejiang University School of Medicine in China and appeared in Neurology on 20 May 2026. The team used the Health and Retirement Study, a long-running American survey of adults aged 50 and over. They analysed 32,802 people who did not have dementia when they joined and whose average age was 61. The participants were followed for about ten years on average, within data collected between 1995 and 2020.

Every two years, participants were interviewed about their smoking, weight and health, and their memory and thinking were checked with simple tests and with reports from people who knew them. At the start, about 20 percent were current smokers, 36 percent were former smokers and 43 percent had never smoked. The question of interest was people who stopped during the study: someone counted as having quit if they reported smoking at one interview but not at the next.

What they found

During the study, 5,868 participants developed dementia. After the researchers adjusted for factors including age, physical activity and cardiovascular health, people who quit smoking had a 16 percent lower risk of dementia than people who carried on smoking.

The link also changed with time. The longer people had been smoke-free, the lower their risk, and after about seven years it was similar to that of people who had never smoked.

What about gaining weight?

Many people worry about putting on weight when they stop, so the researchers looked at that too. People who gained no weight, or up to about 11 pounds (5 kilograms), still had a lower dementia risk and slower cognitive decline than people who kept smoking. Those who gained about 22 pounds (10 kilograms) or more showed no clear cognitive benefit. The summaries we have do not say what happened between those two amounts. A modest gain, in other words, did not seem to erase the pattern, while a large one did. Nothing here suggests that weight is a reason to put off quitting.

The honest limits

This is an observational study. It shows an association and cannot prove that quitting lowers dementia risk. People who manage to quit may differ from people who do not in ways that are hard to measure, such as health, income or other habits. Adjusting for known factors reduces that problem but cannot remove it. Smoking and weight were reported by the participants themselves, so some answers may be remembered inaccurately.

Our account is based on the journal's press release and news coverage, not on the full paper. We have not seen confidence intervals, so we cannot say how precise the 16 percent figure is. The participants were Americans, and we do not know how far the results carry over to other settings.

What this may mean for you

For anyone who smokes, the message is not only about dementia. Stopping has long been recommended for the heart, the lungs and much else. This study adds a possible benefit for the brain that seems to build up over several years. It also hints that it need not be too late: the typical participant was 61 when the study began.

Stopping is hard, and many people need several attempts. Support helps. Your doctor or pharmacist can talk through which kind of help might suit you.

A small, steady habit

Quitting is a good example of a habit built in small steps. Treeny is built around that same idea. The daily exercises are short, and Flo, the coach inside the app, adjusts them to how you are doing each day. It is one gentle way to keep your mind active, alongside everything else you do for your health. It is not a way to prevent or treat any condition, and it is not a quit-smoking programme.

A note on how to read this

This article describes research and is not medical advice. The study discussed shows an association and cannot show that quitting smoking prevents dementia. If you are worried about your memory or your risk of dementia, or you would like to stop smoking, speak to your doctor, who knows your situation in a way no article can.