Neural correlates of age-related hearing loss: An MRI and FDG-PET study

Age-related hearing loss (ARHL) is a common problem among older adults and contributes to adverse health outcomes such as cognitive impairment. However, the neural mechanisms underlying ARHL remain unclear. We aimed to reveal the structural and metabolic (i.e., neural activity) correlates of ARHL using magnetic resonance imaging (MRI) and positron emission tomography with 18F-fluorodeoxyglucose (FDG-PET).

A total of 162 community-dwelling older adults without cerebral disorders or cognitive impairment (Mini-Mental State Examination score < 24) were included in this study. Auditory acuity was measured using a pure-tone average (PTA) of hearing thresholds for the better-hearing ear for 0.5-4-kHz tones. ARHL was defined as a PTA of >40 dB (i.e., greater than moderate hearing loss). The participants then underwent MRI and FDG-PET at rest to assess changes in brain structure and activity associated with ARHL.

Among the 162 participants, 27 (16.6%) had ARHL. A region-of-interest analysis focusing on the bilateral superior temporal gyrus showed significantly lower glucose metabolism in this region, including in the auditory cortex (BA 41 and 42), in participants with ARHL than in those without ARHL. In contrast, no significant structural differences were observed between the groups.

These findings suggest that, prior to structural changes, the effects of ARHL may manifest in neural activity, which is strongly reflected in the regions involved in auditory processing. It is possible that ARHL first alters neural activity in auditory-related regions owing to reduced auditory stimulation. Geriatr Gerontol Int 2025; 25: 300-306.