Overview

• The study, published in The Lancet Healthy Longevity, pooled data from 9,436 adults aged 40 and over and matched 4,700 quitters to 4,700 continuing smokers across England, the US and 10 other European countries.
• Cognitive trajectories were similar while participants were still smoking, then diverged over the six years after cessation, with memory decline about 20% slower and verbal fluency decline roughly halved among quitters.
• In practical terms, those who quit experienced an estimated three to four months less memory decline and about six months less fluency decline per year compared with those who kept smoking.
• Researchers and external experts emphasized the analysis is observational and may be affected by unmeasured differences, with Alzheimer’s Research UK calling for studies that directly assess dementia outcomes.
• Scientists point to vascular damage, inflammation and oxidative stress as plausible pathways, and public‑health advocates say the findings bolster the case for expanded cessation support for middle‑aged and older smokers.