Tobacco smoking was examined as a risk for dementia and neuropathological burden in 531 initially cognitively normal older adults followed longitudinally at the University of Kentucky’s Alzheimer’s Disease Center. The cohort was followed for an average of 11.5 years; 111 (20.9%) participants were diagnosed with dementia, while 242 (45.6%) died without dementia. At baseline, 49 (9.2%) participants reported current smoking (median pack-years = 47.3) and 231 (43.5%) former smoking (median pack-years = 24.5). The hazard ratio (HR) for dementia for former smokers versus never smokers based on the Cox model was 1.64 (95% CI: 1.09, 2.46), while the HR for current smokers versus never smokers was 1.20 (0.50, 2.87). However, the Fine-Gray model, which accounts for the competing risk of death without dementia, yielded a subdistribution hazard ratio (sHR) = 1.21 (0.81, 1.80) for former and 0.70 (0.30, 1.64) for current smokers. In contrast, current smoking increased incidence of death without dementia (sHR = 2.38; 1.52, 3.72). All analyses were adjusted for baseline age, education, sex, diabetes, head injury, hypertension, overweight, APOE ɛ4, family history of dementia, and use of hormone replacement therapy. Once adjusted for the competing risk of death without dementia, smoking was not associated with incident dementia. This finding was supported by neuropathology on 302 of the participants.
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This research was partially funded with support from the following grants to the University of Kentucky’s Sanders-Brown Center on Aging: R01 AG038651 and P30 AG028383 from the National Institute on Aging, R01 NS014189 from the National Institute of Nursing Research, as well as a grant to the University of Kentucky’s Center for Clinical and Translational Science, UL1TR000117, from the National Center for Advancing Translational Sciences.
Abner, Erin L.; Nelson, Peter T.; Jicha, Gregory A.; Cooper, Gregory E.; Fardo, David W.; Schmitt, Frederick A.; and Kryscio, Richard J., "Tobacco Smoking and Dementia in a Kentucky Cohort: A Competing Risk Analysis" (2019). Epidemiology and Environmental Health Faculty Publications. 38.