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.