Smoking cessation and the risk of dementia

A cohort study to examine the associated incidence of dementia with changes in smoking intensity.
Participants were divided into the following groups: quitters (stopped smoking), reducers I (decreased cigarettes by ≥50%), reducers II (decreased cigarettes by 20–50%), sustainers, and increasers (increased cigarettes by ≥20%).
The quitter group had a significantly lower risk of dementia (adjusted hazard ratio [aHR] 0.92; 95% CI, 0.87–0.97), and the reducer I and increaser groups had a significantly higher risk of dementia (aHR, 1.25; 95% CI, 1.18–1.33) and (aHR, 1.12; 95% CI, 1.06–1.18), respectively, compared to sustainers.