Association of pulmonary function with mild cognitive impairment, its progression to dementia and brain pathologies: A community‐based cohort study

Abstract

AbstractBackgroundThe association of pulmonary function (PF) with mild cognitive impairment (MCI) and its underlying mechanisms remain unclear. We examined the association of PF with MCI and its progression to dementia, and brain pathologies.MethodWithin the Rush Memory and Aging Project, the 1,312 dementia‐free participants (mean age: 79.41±7.77 years) included a cognitively intact group (n = 985) and an MCI group (n = 327). The two groups were followed for up to 21 years to detect incident MCI and dementia. PF was assessed with a composite score based on forced vital capacity, forced expiratory volume in 1s, and peak expiratory flow measured at baseline, and further divided into tertiles (i.e., lowest, middle, and highest). MCI and dementia were diagnosed following standard criteria. During the follow‐up, 540 participants died and underwent autopsies for neuropathological assessment (including Alzheimer’s disease [AD], and vascular brain pathologies). Data were analyzed using Cox regression, Laplace regression, and logistic regression.ResultDuring the follow‐up (median 7 years, interquartile range 4‐10 years), 461 participants developed MCI in the cognitively intact group, and 324 had dementia among participants with MCI. Compared to the highest PF, the multi‐adjusted hazard ratios (HRs) with 95% confidence intervals (CIs) were 1.95 (1.43‐2.66) for MCI in the cognitively intact group, and 1.55 (1.03‐2.33) for dementia in the MCI group, respectively. The median time from MCI to dementia development was 2.75 (95% CI: 2.15‐3.34) years shorter in people with the lowest PF than those with the highest PF. In the pathological data analysis, the lowest PF was significantly related to higher AD pathology (odds ratio [OR]: 1.32, 95% CI 1.19‐1.47) and vascular brain pathologies (OR: 3.05, 95% CI 1.49‐6.25) compared to the highest PF.ConclusionThe lowest PF is associated with nearly 2‐fold risk of MCI and accelerates progression from MCI to dementia by almost 3 years. Both neurodegenerative and vascular mechanisms may underlie this association.