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

INTRODUCTION: The relationship between pulmonary function (PF) and mild cognitive impairment (MCI), dementia, and brain pathologies remains unclear. METHODS: A total of 1312 dementia‐free participants, including a cognitively intact group (n = 985) and an MCI group (n = 327), were followed for up to 21 years to detect incident MCI and dementia. PF was assessed at baseline with a composite score and tertiled. Over follow‐up, 540 participants underwent autopsies for neuropathological assessment. RESULTS: Compared to the highest PF, the hazard ratios (95% confidence intervals [CIs]) of the lowest PF 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. Low PF was further related to Alzheimer's disease pathology (odds ratio [OR] 1.32, 95% CI 1.19‐1.47) and vascular pathology (OR 3.05, 95% CI 1.49‐6.25). DISCUSSION: Low PF increases MCI risk and accelerates MCI progression to dementia. Both neurodegenerative and vascular mechanisms may underlie the PF‐dementia association.