Cigarette smoking is associated with a higher risk of Alzheimer's disease (AD), but the underlying mechanisms remain to be clarified. In this study, we aimed to examine the effects of cigarette smoking on multiple AD biomarkers among older individuals with normal cognition (NC). Among 415 older individuals with NC from the Alzheimer's disease Neuroimaging Initiative (ADNI) cohort, we examined the associations between smoking status (non-smokers vs smokers) and global cognition, verbal memory, hippocampal volumes, cerebral glucose metabolism and CSF AD pathologies. The primary findings of this study were: (1) In NC, smokers showed worse performance on verbal memory tests [Rey Auditory Verbal Learning Test (RAVLT) total learning score and delayed recall] than non-smokers; (2) Compared with non-smokers, smokers had significantly lower HpVR; (3) Smokers, relative to non-smokers, demonstrated lower levels of cerebral glucose metabolism as measured by FDG-PET; and (4) there were no significant differences in CSF AD pathologies (CSF Aβ42, t-tau or p-tau) between non-smokers and smokers. Longitudinal studies are needed to investigate the relationship between cigarettes smoking and changes in AD-related markers over time. Further, ADNI participants were highly educated and predominantly white. This may limit the generalizability of our results. In summary, among individuals with NC, cigarette smoking was associated with memory impairment, hippocampal atrophy and cerebral glucose hypometabolism, but not CSF AD pathologies.
