Population-attributable fractions for modifiable risk factors across the continuum of cognitive decline: Hubei Memory and Aging Cohort Study

Background The increasing prevalence of dementia, especially in nations such as China, emphasizes the importance of targeting modifiable risk factors for primary prevention. However, the extent to which these factors contribute to the population-attributable fractions (PAFs) across the spectrum of cognitive decline remains unclear. Objective This study aimed to investigate changes in risk factors along the dementia continuum and identify common risk factors by constructing PAFs for subjective cognitive decline (SCD), mild cognitive impairment (MCI), and dementia among older adults in rural and urban China. Methods We present a cross-sectional analysis of data from the 2018–2023 rounds of the dongoing Hubei Memory and Aging Cohort Study, including 8827 Chinese older adults (mean age 72.5 ± 5.9 years, 55.2% female, and 37.3% rural residents). We calculated the weighted population attributable fraction (PAFs) of 22 modifiable risk factors for SCD, MCI, and dementia, which included the 12 risk factors for dementia in the model of the 2024 Lancet Commission and 10 new factors. Results Using data from 8827 Chinese older adults, we revealed that an estimated 22.87%, 39.00%, and 60.15% of the individuals with SCD, MCI, and dementia, respectively, were associated with 22 modifiable risk factors. We identified 10 shared modifiable risk factors that accounted for SCD (20.83%), MCI (24.12%), and dementia (42.26%). Additionally, the rural residents exhibited greater weighted PAFs across the cognitive decline continuum than urban residents. However, we did not observe significant sex differences in these associations. Conclusions PAFs of risk factors vary substantially across the cognitive decline continuum.