Abstract
Although recent studies show that age-related hearing impairment is associated with cerebral changes, data from a population perspective are still lacking. Therefore, we studied the relation between hearing impairment and brain volume in a large elderly cohort. From the population-based Rotterdam Study, 2,908 participants (mean age 65 years, 56% female) underwent a pure-tone audiogram to quantify hearing impairment. By performing MR imaging of the brain we quantified global and regional brain tissue volumes (total brain volume, gray matter volume, white matter (WM) volume, and lobe-specific volumes). We used multiple linear regression models, adjusting for age, sex, head size, time between hearing test and MR imaging, and relevant cognitive and cardiovascular covariates. Furthermore, we performed voxel-based morphometry to explore sub-regional differences. We found that a higher pure-tone threshold was associated with a smaller total brain volume [difference in standardized brain volume per decibel increase in hearing threshold in the age-sex adjusted model: -0.003 (95% confidence interval -0.004; -0.001)]. Specifically, WM volume was associated. Both associations were more pronounced in the lower frequencies. All associations were consistently present in all brain lobes in the lower frequencies and in most lobes in the higher frequencies, and were independent of cognitive function and cardiovascular risk factors. In voxel-based analyses we found associations of hearing impairment with smaller white volumes and some smaller and larger gray volumes, yet these were statistically non-significant. Our findings demonstrate that hearing impairment in elderly is related to smaller total brain volume, independent of cognition and cardiovascular risk factors. This mainly seems to be driven by smaller WM volume, throughout the brain.
Highlights
Age-related hearing impairment is common in the middle-aged and elderly population (Cruickshanks et al, 2003; Nash et al, 2011; Fischer et al, 2014)
One of the most commonly studied cerebral regions with regard to hearing impairment is the central auditory pathway, yet the evidence remains inconsistent; some studies demonstrated a relation between hearing impairment and smaller gray matter (GM) volume in this region (Husain et al, 2011; Peelle et al, 2011; Eckert et al, 2012), whereas others found an association with smaller white matter (WM) volume (Chang et al, 2004; Husain et al, 2011), or no association with any brain volume (Profant et al, 2014)
When brain tissues were analyzed separately, the association with the pure-tone audiogram appeared to be driven by WM volume only
Summary
Age-related hearing impairment is common in the middle-aged and elderly population (Cruickshanks et al, 2003; Nash et al, 2011; Fischer et al, 2014). The ability to understand speech in noise declines (Gates and Mills, 2005), leading to communication difficulties that have a large impact on a person’s social, psychological, and physical well-being (Dalton et al, 2003)
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