Neurotransmitter Imbalance in Age-Related Hearing Loss: An MRS Study of the Auditory Cortex

Recent advances in spectral editing magnetic resonance spectroscopy (MRS) allow reliable quantification of γ-aminobutyric acid (GABA) and glutamate concentrations in the human brain. Both GABA as well as glutamate play important roles in the auditory system. The present study investigated how age, auditory cortex neurotransmitter levels (GABA+, glutamate), and hearing abilities interact, with a focus on both objective and subjective measures of hearing impairment. Although age-related hearing loss is common, the mechanisms linking auditory decline to changes in GABAergic and glutamatergic systems remain unclear. Clarifying these relationships is essential for determining whether neurotransmitter concentrations may serve as potential targets for interventions aimed at reducing listening effort and improving speech perception. Young adults (n = 23, aged 18–35 years) with normal hearing abilities and older adults (n = 55, aged 50–77 years) with normal hearing to varying degrees of age-related hearing loss completed MRS of the auditory cortex, pure-tone audiometry, speech-in-noise perception, and questionnaires assessing daily life listening effort and subjective hearing impairment. Older adults showed higher GABA+ and lower glutamate/tCr levels compared to young adults. Across the older participants, higher subjective hearing impairment was associated with lower GABA+ concentrations. Exploratory analyses further indicated that, within the older adult group, higher glutamate levels were linked to better cognitive performance. Together, these findings provide initial evidence that age-related variability in inhibitory and excitatory neurotransmitters relates to perceived hearing difficulties and cognitive performance, which may help identify biological pathways relevant for future intervention strategies.