Effects of Aging and Adult-Onset Hearing Loss on Cortical Auditory Regions.

Velia Cardin

doi:10.3389/fnins.2016.00199

Abstract

Hearing loss is a common feature in human aging. It has been argued that dysfunctions in central processing are important contributing factors to hearing loss during older age. Aging also has well documented consequences for neural structure and function, but it is not clear how these effects interact with those that arise as a consequence of hearing loss. This paper reviews the effects of aging and adult-onset hearing loss in the structure and function of cortical auditory regions. The evidence reviewed suggests that aging and hearing loss result in atrophy of cortical auditory regions and stronger engagement of networks involved in the detection of salient events, adaptive control and re-allocation of attention. These cortical mechanisms are engaged during listening in effortful conditions in normal hearing individuals. Therefore, as a consequence of aging and hearing loss, all listening becomes effortful and cognitive load is constantly high, reducing the amount of available cognitive resources. This constant effortful listening and reduced cognitive spare capacity could be what accelerates cognitive decline in older adults with hearing loss.

Highlights

Normal aging in humans is often accompanied by hearing loss (Lin et al, 2011b; Humes et al, 2012)
↓ GM volume associated with high-frequency hearing loss in auditory regions, in left te1.0
Increased pupil dilation and cognitive load are in turn associated with increased activation of cortical auditory regions, and frontal ones (Zekveld et al, 2014), supporting the idea that in older listeners with hearing loss more resources are allocated for listening in clear conditions

Summary

Introduction

Normal aging in humans is often accompanied by hearing loss (Lin et al, 2011b; Humes et al, 2012). Of those studies measuring morphometric changes in auditory cortices, two have showed a positive correlation between hearing loss and reductions in gray matter volume (Peelle et al, 2011; Eckert et al, 2012), whereas other two did not find an effect (Boyen et al, 2013; Profant et al, 2014).

Results

Conclusion