Hearing Loss Linked to Faster Brain Atrophy and Cognitive Decline in Older Adults: Study

Hearing loss has been proposed as a modifiable risk factor for dementia, but the specific pathways involved are not well understood. This study aimed to investigate how hearing impairment relates to brain atrophy and cognitive decline, and whether pathological processes such as Alzheimer's disease and cerebrovascular disease influence these relationships.

The study analyzed data from 287 adults born in the same week of 1946 who underwent baseline pure tone audiometry at an average age of 70.6 years. Participants also underwent two time point cognitive assessment and multimodal brain imaging with a mean interval of 2.4 years. Hearing impairment was defined as a pure tone average of greater than 25 decibels in the best hearing ear. Rates of change for whole brain, hippocampal, and ventricle volume were estimated from structural MRI. Cognitive function was assessed using the Pre-clinical Alzheimer’s Cognitive Composite. Regression models were used to evaluate the associations between baseline hearing impairment, brain atrophy, and cognitive decline, adjusting for confounding factors including β-amyloid deposition and white matter hyperintensity volume.

The key findings of the study were as follows:

• Out of the 287 participants, 111 had hearing impairment.

• Hearing impaired individuals had faster rates of whole brain atrophy compared to those with preserved hearing.

• Worse hearing (higher pure tone average) predicted faster rates of hippocampal atrophy.

• In participants with hearing impairment, faster rates of whole brain atrophy were associated with greater cognitive decline.

• These relationships were independent of β-amyloid deposition and white matter hyperintensity volume, suggesting that hearing loss may influence dementia risk via distinct pathways.

The study suggests that hearing loss may contribute to dementia risk through pathways separate from those typically associated with Alzheimer's and cerebrovascular disease. Understanding these pathways could lead to new strategies for dementia prevention and intervention in older adults with hearing impairment.

Reference:

Parker, T. D., Hardy, C., Keuss, S., Coath, W., Cash, D. M., Lu, K., Nicholas, J. M., James, S.-N., Sudre, C., Crutch, S., Bamiou, D.-E., Warren, J. D., Fox, N. C., Richards, M., & Schott, J. M. (2024). Peripheral hearing loss at age 70 predicts brain atrophy and associated cognitive change. Journal of Neurology, Neurosurgery, and Psychiatry, jnnp-2023-333101. https://doi.org/10.1136/jnnp-2023-333101