Age-related hearing loss occurs for just about everyone. We wondered about the potential impact of hearing loss on brain structure because speech recognition can be difficult even after correcting for poor hearing thresholds. In a sample of 49 older adults, we observed that high frequency hearing loss was associated with lower gray matter volume in auditory cortex. Importantly, Dr. Kelly Harris from our Hearing Research Program has observed that individual differences in auditory cortex structure relates to individual differences in hearing thresholds even before hearing loss is considered clinically significant. These findings emphasize the importance of protecting your hearing and suggest that starting to wear hearing aids as early as possible may limit potential changes in brain structure.
But what about low frequency hearing? In a follow-up study of 72 older adults, we tested a long-standing hypothesis that low frequency hearing loss occurs with vascular disease affecting vessels supporting the cochlea and the brain. We examined the extent to which evidence for small vessel disease in the white matter of the brain was associated with low frequency hearing thresholds in older adults. Variation in frontal white matter was related to low frequency hearing variation in women and people with a history of high blood pressure. These results suggest that people with high blood pressure are at risk for low frequency hearing loss. Future studies are necessary to determine if these findings can be explained by how well high blood pressure is controlled and/or the duration of high blood pressure before people seek treatment, for example.