Background: Smoking starts in early adulthood and persists throughout the life course, but the association between these trajectories and midlife cognition remains unclear. Objective: Determine the association between early to midlife smoking trajectories and midlife cognition. Design: Prospective cohort study. Participants: Participants were 3364 adults (mean age = 50.1 ± 3.6, 56% female, 46% Black) from the Coronary Artery Risk Development in Young Adults (CARDIA) study: 1638 ever smokers and 1726 never smokers. Main Measures: Smoking trajectories were identified in latent class analysis among 1638 ever smokers using smoking measures every 2–5 years from baseline (age 18–30 in 1985–1986) through year 25 (2010–2011). Poor cognition was based on cognitive domain scores ≥ 1 SD below the mean on tests of processing speed (Digit Symbol Substitution Test), executive function (Stroop), and memory (Rey Auditory Verbal Learning Test) at year 25. Results: Five smoking trajectories emerged over 25 years: quitters (19%), and minimal stable (40%), moderate stable (20%), heavy stable (15%), and heavy declining smokers (5%). Heavy stable smokers showed poor cognition on all 3 domains compared to never smoking (processing speed AOR = 2.22 95% CI 1.53–3.22; executive function AOR = 1.58 95% CI 1.05–2.36; memory AOR = 1.48 95% CI 1.05–2.10). Compared to never smoking, both heavy declining (AOR = 1.95 95% CI 1.06–3.68) and moderate stable smokers (AOR = 1.56 95% CI 1.11–2.19) exhibited slower processing speed, and heavy declining smokers additionally had poor executive function. For minimal stable smokers (processing speed AOR = 1.12 95% CI 0.85–1.51; executive function AOR = 0.97 95% CI 0.71–1.31; memory AOR = 1.21 95% CI 0.94–1.55) and quitters (processing speed AOR = 0.96 95% CI 0.63–1.48; executive function AOR = 0.98 95% CI 0.63–1.52; memory AOR = 0.97 95% CI 0.67–1.39), no association was observed. Conclusions: The association between early to midlife smoking trajectories and midlife cognition was dose-dependent. Results underscore the cognitive health risk of moderate and heavy smoking and the potential benefits of quitting on cognition, even in midlife.
Bibliographical noteFunding Information:
The Coronary Artery Risk Development in Young Adults (CARDIA) Study is conducted and supported by the National Heart, Lung, and Blood Institute (NHLBI) in collaboration with the University of Alabama at Birmingham (HHSN268201800005I & HHSN268201800007I), the Northwestern University (HHSN268201800003I), the University of Minnesota (HHSN268201800006I), and the Kaiser Foundation Research Institute (HHSN268201800004I). The CARDIA Cognitive ancillary study is supported by the National Institute on Aging grant R01 AG063887-01 (NIA Multiple-PI: K Yaffe and S Sidney). This research is also supported by the NIA grant K24 AG031155 (PI: K Yaffe). This manuscript has been reviewed by CARDIA for scientific content.
- cigarette smoking
- cognitive aging
- cognitive function
- tobacco use
PubMed: MeSH publication types
- Journal Article