Researchers examined nearly 33,000 American adults without dementia and published their findings in the journal Neurology.
Participants were regularly asked about their health, weight, and lifestyle habits. They also completed tests measuring memory and thinking abilities.
At the beginning of the study, around 20 percent of participants were smokers, while many others were former smokers. The rest had never smoked.
During the course of the study, nearly 5,900 people developed dementia, according to HealthDay.
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The importance of weight
The researchers also found that body weight may play a role.
People who gained a significant amount of weight after quitting smoking did not appear to receive the same benefits as other participants.
According to lead researcher Hui Chen from Zhejiang University School of Medicine, future studies should take a closer look at how weight and other health habits affect the brain as people age.
The study also showed that the risk changed over time. After around seven years, people who had quit smoking had almost the same risk of dementia as those who had never smoked.
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The risk declined
Overall, people who quit smoking had a 16 percent lower risk of dementia than those who continued smoking.
The benefit was greatest among people who avoided major weight gain after quitting. Participants with substantial weight gain did not show the same reduced risk.
Sources: HealthDay and Neurology.
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