Functional-Structural Coupling: Brain Reorganization in Presbycusis Is Related to Cognitive Impairment

Presbycusis, a prevalent neurodegenerative disorder, is characterized by declining speech recognition and has been associated with cognitive impairments across multiple domains. However, the underlying neurobiological mechanisms between presbycusis and cognitive impairments remain unclear. We assessed pure-tone audiometry thresholds (PTA), speech recognition thresholds (SRT), and cognitive abilities in individuals with presbycusis (24 males and 31 females) and healthy controls (23 males and 32 females). Using magnetic resonance imaging, we calculated the amplitude of low-frequency fluctuations (ALFF) to characterize function and gray matter volume (GMV) to characterize structure. Based on ALFF and GMV, we calculated functional-structural ratio (FSR) to measure the functional-structural coupling. Significant correlations between GMV atrophy and ALFF changed in the putamen, fusiform gyrus, precuneus, and medial superior frontal gyrus in presbycusis group, and these changes were significantly associated with the increase in PTA and SRT. The FSR reduction in the FFG, precuneus, and medial superior frontal gyrus were also significantly associated with the increase in PTA and SRT. Moreover, it was also significantly correlated with lower scores on the Montreal Cognitive Assessment (MoCA) and the Auditory Verbal Learning Test (AVLT), as well as the prolonged time in the Trail Making Test (TMT-A). Presbycusis involves coupled structural atrophy and functional decline in auditory and higher-order cognitive regions. Crucially, reduced FSR correlates with both worsening hearing thresholds and cognitive impairment. This highlights FSR as a key neurobiological link between hearing loss and cognitive decline. This research provides a novel basis for early screening and dynamic monitoring of presbycusis-related cognitive impairment.