Study Finds Quitting Smoking Cuts Dementia Risk 16% as 10-Kilogram Weight Gain Erases Benefit
Updated
Updated · ScienceAlert · Jun 4
Study Finds Quitting Smoking Cuts Dementia Risk 16% as 10-Kilogram Weight Gain Erases Benefit
3 articles · Updated · ScienceAlert · Jun 4
Summary
More than 32,000 dementia-free U.S. retirees followed for 25 years showed a 16% lower dementia risk after quitting smoking versus continuing smokers, according to a study published in Neurology.
The benefit largely held for people who kept weight stable or gained less than 5 kilograms within two years of quitting; gaining more than 10 kilograms removed the significant link to lower dementia risk.
Nearly 6,000 dementia cases were recorded, and cognitive testing showed quitters—especially those with little weight gain—had about 20% slower cognitive decline than continuing smokers.
Never-smokers had a 25% lower dementia risk than current smokers, while prior research cited in the report suggests smoking can raise dementia odds by 30% to 50%.
The authors said the observational findings cannot prove cause and effect, but argue smoking-cessation advice should also stress weight management to preserve potential brain-health gains.
You quit smoking to save your brain. Could gaining weight completely undo all the cognitive benefits?
Why do two recent studies offer opposite conclusions on smoking cessation and long-term brain health?
Quitting Smoking Cuts Dementia Risk by 16%—But Major Weight Gain Can Erase the Benefit, Landmark Study Finds
Overview
A major 2026 study followed over 32,800 adults aged 50 and older for about ten years to explore how quitting smoking and weight gain affect dementia risk. The research found that people who quit smoking had a 16% lower risk of developing dementia compared to those who kept smoking, showing that stopping smoking is a strong step for better brain health. However, this benefit was not the same for everyone. Those who quit and gained about 11 pounds or less still enjoyed a lower risk and slower decline in thinking skills, but larger weight gains erased these advantages, highlighting the need for healthy weight management after quitting.