The effects of demographic and health-related factors on the association between hearing loss and cognitive decline in the Chinese population over 45 years old

Background As low- and middle-income countries are experiencing population aging, they increasingly confront with the challenge of escalating dementia rate. The association between hearing condition and dementia is widely discussed, but the nature of this relationship is still uncertain.

Methods This study utilized data from a large-scale longitudinal study from 2011 to 2018, which included a representative sample of individuals aged over 45 years in China. Hearing status was indexed by a five-level self-reported question, and cognitive performance and incidence of dementia was assessed using the Telephone Interview of Cognitive Status (TICS). In The association between hearing loss and cognitive decline was examined using logistic regression and linear regression after adjusting for demographic, health-related, and socioeconomic factors. Additionally, two group-based trajectory models (GBTMs) were conducted to determine the potential risk factors for dementia longitudinally.

Results The results show that cognitive impairment was significantly associated with hearing loss. In cross-sectional model, older age, single marital status, rural location, low educational level, low living expenditure, reduced social activities, and depressed mental status were found to be significantly associated with both hearing loss and cognitive decline at least two distinct time point. In the longitudinal GBTM, compared with participants with better cognitive function, participants with lower cognitive levels had worse hearing condition (coefficient 0.18 with 0.07 standard error, p<0.05). Meanwhile, depressed mental status, vision impairment, low educational attainment, older age, single marital status, rural location, and reduced social activities were significantly related to dementia and its correlation with hearing status. Additionally, he introduction of allostatic load data weakens the association between hearing ability and cognitive performance.

Conclusion Cognitive performance and incident dementia was associated with self-reported hearing loss in Chinese people over 45 years old. The strength of this relationship is influenced by demographic and health-related factors, and the existing of allostatic load decreased the salience of hearing loss for cognitive performance and incident dementia.