Moderating effect of hearing aids on association between hearing loss and brain structure?
Reviewed by Patricia Ward

Previous studies have suggested links between age-related hearing loss and structural changes in cortical regions with auditory and language functions, which could be causative of cognitive decline linked to the condition. The authors reason reduced sensory input could be causative and that, if so, hearing aid use could moderate these changes through prevention of sensory deprivation as some observational studies have indicated - others found no significant effect. Research continues, mostly using cognitive measures as outcome. This cross-sectional study (459 participants, mean age 70.4 years) investigated the moderating effect of hearing aid use on the association between hearing loss and reduced brain volume, and reduced white matter integrity, by looking for anatomical differences in brains of hearing aid users compared to non-users. Participants with pure tone audiometry (PTA) average of ≥ 35 dB sensorineural hearing loss (1, 2 and 4 kHz) were taken from the larger Rotterdam Study, which includes magnetic resonance imaging (MRI) and PTA in its core study protocol. MRI images were visually evaluated and used to quantify total brain, gray and white matter volumes, as well as volumes for both temporal lobes and to assess white matter integrity by calculating fractional anisotropy (FA) and mean diffusivity (MD) – lower FA and higher MD indicating poorer integrity. Following analysis, no evidence of a moderating effect of hearing aids in the association of hearing loss with either brain volume or white matter integrity was found, but a possible moderating effect of hearing aids on the link between age and white matter integrity was. This requires further longitudinal study to try to identify the mechanism and properly control for other factors such as the positive effect of hearing aid use on social isolation, especially as the results differ from those suggested by other studies.

The effect of hearing aid use on the association between hearing loss and brain structure in older adults.
de Boer TG, Rigters SC, Croll PH, et al.
EAR HEAR
2022;43(3):933-40.