CORRELATION BETWEEN PERIPHERAL HEARING LOSS AND CENTRAL AUDITORY DYSFUNCTION IN ALZHEIMER’S DISEASE

Hearing loss is strongly associated with accelerated cognitive decline and an increased risk of dementia, including Alzheimer’s Disease (AD). While social isolation following hearing loss has been proposed as a contributing factor to dementia, emerging evidence suggests that AD-related neurodegeneration may itself disrupt auditory processing, creating a bidirectional relationship between sensory and cognitive decline. Auditory information is transmitted along the auditory pathway via action potentials through spiral ganglion neurons and successive central auditory nuclei, before reaching the auditory cortex. In this study, we investigated the correlation between hearing loss and AD in 3×Tg-AD mice. Auditory brainstem response (ABR) recordings revealed prolonged wave latencies in 24-month-old 3×Tg-AD mice compared with controls, indicating functional deficits along the auditory pathway.Histological analysis of 3×Tg-AD mice cochlea demonstrated near-complete loss of the spiral ganglion neurons (SGNs), accompanied by a marked reduction in cochlear afferent nerve fibers, linking severe peripheral degeneration to central auditory dysfunction. Analyses of the inferior colliculus and auditory cortex further revealed molecular alterations consistent with impaired central auditory processing. Notably, neuron-specific overexpression of K_V3.1 and K_V 3.3 channels, key proteins for auditory signal transmission, was detected in 18-month-old AD mice, suggesting that central auditory nuclei are also affected in the AD.These findings demonstrate a correlation between peripheral neurosensory loss and central auditory deficits in AD. By establishing this link, our study provides new insights into how sensory system alterations contribute to cognitive decline and underscores the potential of auditory pathway changes as early indicators of Alzheimer’s disease.