The Association Between Hearing Loss and Cognition: The Role of Cognitive Reserve in Individuals with Age-Related Hearing Loss Using Structural Equation Modelling (SEM)

Hearing loss is currently the third most common health issue worldwide (GBD 2016 Disease and Injury Incidence and Prevalence Collaborators, 2017). One subtype of hearing loss is age-related hearing loss (ARHL), which is a gradual and irreversible aspect of aging, mostly affecting older people (over 65 years old). There is strong evidence that ARHL affects cognitive functions in addition to the auditory system. Loughrey et al. (2018) conducted a meta-analysis and examined the association between age-related hearing loss and cognitive outcomes. They reported significant positive associations between ARHL and cognitive decline, as well as dementia. Therefore, Age-related hearing loss (ARHL) might be considered as a modifiable risk factor for dementia and cognitive decline (Livingston et al., 2024). Cognitive Reserve (CR) is thought to be a potential factor that modulates the strength and direction of the relationship between age-related hearing loss and cognitive functions. Cognitive Reserve is a theoretical construct referring to the brain's resilience to neuropathological damage, enabling people to maintain cognitive functioning despite aging or disease-related changes (Stern, 2012). Education, leisure time activities, and occupation are mainly used as proxies for CR, which are considered to buffer against cognitive decline (Scarmeas & Stern, 2003). For example, individuals with lower educational attainment have been reported to exhibit a substantially higher risk of dementia compared to those with higher levels of education and occupational complexity (Stern, 2012). Subsequently, a meta-analysis study revealed that education has a moderating effect between hearing loss and cognitive impairment (Loughrey et al., 2018). ARHL and cognitive functions are influenced by additional modifiable risk factors. For instance, cognitive decline has been linked to lifestyle-related factors. Lifestyle factors such as physical activity, non-smoking, and regular social engagement may influence cognitive processes and slow cognitive decline (Dominguez et al., 2021; Livingston et al., 2024). A systematic and meta-analysis study examined the relationship among different types of lifestyle factors, cognitive decline, and dementia, revealing that factors such as physical exercise, diet, and sleep patterns slowed the onset of dementia and improved cognitive functions (Dominguez et al., 2021). Zhao et al. (2024) demonstrated that healthy lifestyle factors reduce cognitive impairment risk by 37% and significantly attenuate the hearing loss–cognition association. Nonetheless, there is insufficient research on the moderating effect of lifestyle factors on ARHL and cognition. The relationship between ARHL and cognitive decline has yet to be clearly established, and moderating effects of cognitive reserve and lifestyle factors remain insufficiently understood. The current study aims to use Structural Equation Modelling (SEM) to investigate the direct and indirect pathways through which hearing loss may affect cognitive function, with cognitive reserve and lifestyle factors as moderators, in individuals with age-related hearing loss and normal hearing controls.