Towards Understanding the Relationship Between Hearing Loss and Cognition in Healthy Aging

Age-related hearing loss (ARHL) has been increasingly linked to cognitive decline, both directly and through structural brain changes. This study utilized data from the Aging Brain Cohort project at the University of South Carolina (ABC@UofSC) to investigate the relationships between hearing impairments, cognitive performance, and gray matter volume across key brain regions. Specifically, the study aimed to: (i) examine the mediating role of gray matter volume in the relationship between ARHL and cognitive impairments; (ii) investigate the role of regional brain age gap in mediating the relationship between ARHL and cognitive decline; and (iii) delineate the distinctive impact of ARHL on specific cognitive domains including memory, attention, and executive function. In a sample of 231 participants aged 20-79 years, cognitive performance was assessed using the Montreal Cognitive Assessment (MoCA), focusing on general cognition, memory, attention, and executive function. Hearing performance was measured through pure-tone thresholds (PTT) and words-in-noise perception (WIN). Correlation analyses were employed to identify brain regions associated with hearing scores, and mediation analyses were conducted to determine whether these brain structures mediated the relationship between hearing impairment and cognitive performance, with a focus on specific cognitive domains such as memory, attention, and executive function. Findings highlighted the involvement of both auditory-specific regions, such as Heschl’s gyrus (HG) and the posterior superior temporal gyrus (pSTG), and non-auditory regions, including the cingulo-opercular (CO) network and domain-general (DG) areas, in mediating the link between hearing loss and cognitive impairment. Notably, the right hemisphere emerged as playing a more dominant role in the neural mechanisms linking hearing loss to cognition, supporting the right hemi-aging hypothesis, which posits greater age-related decline in the right hemisphere, particularly in sensory and cognitive functions. The findings revealed significant associations between hearing scores and general cognitive performance, with partial mediation through structural changes in both auditory and non-auditory regions. Furthermore, WIN scores were found to be more sensitive predictors of cognitive decline than PTT scores, particularly affecting executive control. The mediation analyses also indicated that structural changes in the hippocampus and frontal regions partially explained the link between hearing loss and cognitive deficits, with the right hemisphere playing a prominent role. The study concludes that ARHL contributes to cognitive decline, with structural changes in key brain regions, particularly in the right hemisphere, partially mediating this relationship. These findings provide important insights into the neural mechanisms underlying the hearing-cognition link and contribute to the growing evidence that hearing loss may be a potential modifiable risk factor for cognitive decline in aging populations.