Association of Poorer Hearing With Longitudinal Change in Cerebral White Matter Microstructure.

ABSTRACT

Importance There is a dearth of studies that examine the association between poorer hearing and change in cerebral white matter (WM) microstructure. Objective: To examine the association of poorer hearing with baseline and change in WM microstructure among older adults. Design, Setting, and Participants: This was a prospective cohort study that evaluated speech-in-noise, pure-tone audiometry, and WM microstructure, as measured by mean diffusivity (MD) and fractional anisotropy (FA), both of which were evaluated by diffusion tensor imaging (DTI) in 17 WM regions. Data were collected between October 2012 and December 2018 and analyzed between March 2019 and August 2019 with a mean follow-up time of 1.7 years. The study evaluated responses to the Baltimore Longitudinal Study of Aging among 356 cognitively normal adults who had at least 1 hearing assessment and DTI session. Excluded were those with baseline cognitive impairment, stroke, head injuries, Parkinson disease, and/or bipolar disorder. Exposures Peripheral auditory function was measured by pure-tone average in the better-hearing ear. Central auditory function was measured by signal-to-noise ratio score from a speech-in-noise task and adjusted by pure-tone average. Main Outcomes and Measures: Linear mixed-effects models with random intercepts and slopes were used to examine the association of poorer peripheral and central auditory function with baseline and longitudinal DTI metrics in 17 WM regions, adjusting for baseline characteristics (age, sex, race, hypertension, elevated total cholesterol, and obesity). Results: Of 356 cognitively normal adults included in the study, the mean (SD) age was 73.5 (8.8) years, and 204 (57.3%) were women. There were no baseline associations between hearing and DTI measures. Longitudinally, poorer peripheral hearing was associated with increases in MD in the inferior fronto-occipital fasciculus (ß = 0.025; 95% CI, 0.008-0.042) and the body (ß = 0.050; 95% CI, 0.015-0.085) of the corpus callosum, but there were no associations of peripheral hearing with FA changes in these tracts. Poorer central auditory function was associated with longitudinal MD increases (ß = 0.031; 95% CI, 0.010-0.052) and FA declines (ß = -1.624; 95% CI, -2.511 to -0.738) in the uncinate fasciculus. Conclusions and Relevance Findings of this cohort study suggest that poorer hearing is related to change in integrity of specific WM regions involved with auditory processing.