Overview

• The peer-reviewed analysis in The Lancet Healthy Longevity examined 9,436 adults aged 40 and over across 12 countries, matching more than 4,700 who quit with an equal number who continued smoking.
• Cognitive decline tracked similarly while all participants smoked, then diverged after cessation, with memory declining about 20% more slowly and verbal fluency declining roughly half as fast among quitters over the next six years.
• The authors estimate that, per year of aging, quitters experienced approximately three to four months less memory decline and about six months less decline in verbal fluency than continuing smokers.
• Experts note the study is observational and subject to unmeasured confounders, urging dementia-specific research to test whether quitting directly reduces dementia risk.
• Proposed mechanisms include vascular damage, chronic inflammation and oxidative stress from smoking, and public-health groups say the findings support stronger stop‑smoking services as 11.9% of UK adults smoked in 2023.