Associations of polypharmacy with cognitive impairment and functional status among older adults

Aim: Polypharmacy is increasingly prevalent among older adults and has been suggested as a potential risk factor for adverse health outcomes, including cognitive impairment and functional decline. Therefore, this study aimed to investigate the associations of polypharmacy with cognitive impairment and functional status among community-dwelling older adults using nationally representative data from the 2023 Korean Elderly Survey. Methods: A cross-sectional analysis was conducted using data from 9,898 community-dwelling older adults without a diagnosis of dementia. Polypharmacy was defined as the concurrent use of five or more physician-prescribed medications. Cognitive function was assessed using the Korean version of the Mini-Mental State Examination (K-MMSE), with cognitive impairment defined as a score ≤ 23. Functional status was evaluated using the Korean Activities of Daily Living (K-ADL) and Korean Instrumental Activities of Daily Living (K-IADL). Logistic regression was used to estimate odds ratios and 95% confidence intervals (CIs) for cognitive impairment, while multiple linear regression analyses examined associations with functional status. Models were sequentially adjusted for sociodemographic characteristics, health behaviors, and the number of chronic diseases. Results: Polypharmacy was associated with increased odds of cognitive impairment in the crude model (OR = 1.70, 95% CI: 1.40–2.05); however, this association was attenuated and became non-significant after adjustment for sociodemographic and health-related factors. In contrast, polypharmacy remained independently associated with poorer functional status in fully adjusted models, showing higher K-ADL scores (B = 0.14, p = 0.007) and K-IADL scores (B = 0.43, p < 0.001). Conclusions: Polypharmacy was independently associated with functional impairment but not with cognitive impairment after comprehensive adjustment, suggesting that functional decline may represent a more sensitive and immediate consequence of complex medication use in older adults. These findings underscore the need for comprehensive geriatric assessment approaches that integrate medication review with functional evaluation.