Affiliations: [a]
Kaiser Permanente Washington Health Research Institute, Seattle, WA, USA
| [b] Herbert Wertheim School of Public Health and Human Longevity Science, University of California San Diego, San Diego, CA, USA
| [c] Division of Geriatrics, Gerontology, and Palliative Care, Department of Medicine, University of California San Diego, San Diego, CA, USA
| [d] Department of Radiology, University of California San Diego, San Diego, CA, USA
| [e] Department of Neurosciences, University of California San Diego, San Diego, CA, USA
Correspondence:
[*]
Correspondence to: Linda K. McEvoy, PhD, Kaiser Permanente Washington Health Research Institute, 1730 Minor Ave, Suite 1600, Seattle, WA 98101, USA. Tel.: 206 442 5210; E-mail: Linda.K.McEvoy@kp.org.
Abstract: Background:Hearing loss is associated with cognitive decline and increased risk for Alzheimer’s disease, but the basis of this association is not understood. Objective:To determine whether hearing impairment is associated with advanced brain aging or altered microstructure in areas involved with auditory and cognitive processing. Methods:130 participants, (mean 76.4±7.3 years; 65% women) of the Rancho Bernardo Study of Healthy Aging had a screening audiogram in 2003–2005 and brain magnetic resonance imaging in 2014–2016. Hearing ability was defined as the average pure tone threshold (PTA) at 500, 1000, 2000, and 4000 Hz in the better-hearing ear. Brain-predicted age difference (Brain-pad) was calculated as the difference between brain-predicted age based on a validated structural imaging biomarker of brain age, and chronological age. Regional diffusion metrics in temporal and frontal cortex regions were obtained from diffusion-weighted MRIs. Linear regression analyses adjusted for age, gender, education, and health-related measures. Results:PTAs were not associated with brain-PAD (β= 0.09; 95% CI: –0.084 to 0.243; p = 0.34). PTAs were associated with reduced restricted diffusion and increased free water diffusion primarily in right hemisphere temporal and frontal areas (restricted diffusion: βs = –0.21 to –0.30; 95% CIs from –0.48 to –0.02; ps < 0.03; free water: βs = 0.18 to 0.26; 95% CIs 0.01 to 0.438; ps < 0.04). Conclusions:Hearing impairment is not associated with advanced brain aging but is associated with differences in brain regions involved with auditory processing and attentional control. It is thus possible that increased dementia risk associated with hearing impairment arises, in part, from compensatory brain changes that may decrease resilience.
