Cognitive spare capacity in older adults with hearing loss

Sushmit Mishra,Jerker Rã¶Nnberg,Thomas Lunner,Stefan Stenfelt,Mary Rudner

doi:10.3389/fnagi.2014.00096

Abstract

Individual differences in working memory capacity (WMC) are associated with speech recognition in adverse conditions, reflecting the need to maintain and process speech fragments until lexical access can be achieved. When working memory resources are engaged in unlocking the lexicon, there is less Cognitive Spare Capacity (CSC) available for higher level processing of speech. CSC is essential for interpreting the linguistic content of speech input and preparing an appropriate response, that is, engaging in conversation. Previously, we showed, using a Cognitive Spare Capacity Test (CSCT) that in young adults with normal hearing, CSC was not generally related to WMC and that when CSC decreased in noise it could be restored by visual cues. In the present study, we investigated CSC in 24 older adults with age-related hearing loss, by administering the CSCT and a battery of cognitive tests. We found generally reduced CSC in older adults with hearing loss compared to the younger group in our previous study, probably because they had poorer cognitive skills and deployed them differently. Importantly, CSC was not reduced in the older group when listening conditions were optimal. Visual cues improved CSC more for this group than for the younger group in our previous study. CSC of older adults with hearing loss was not generally related to WMC but it was consistently related to episodic long term memory, suggesting that the efficiency of this processing bottleneck is important for executive processing of speech in this group.

Highlights

Communication is vital for social participation but may be hampered by adverse listening conditions
While listening under adverse conditions, individuals may maintain in working memory fragments of spoken information that are not masked by noise and process them to achieve speech understanding (Rönnberg et al, 2013)
There is evidence that linguistic closure ability supports listening in adverse conditions (Besser et al, 2013; Zekveld et al, 2013) and this may be another process that is recruited into working memory during speech understanding

Summary

Introduction

Communication is vital for social participation but may be hampered by adverse listening conditions. While listening under adverse conditions, individuals may maintain in working memory fragments of spoken information that are not masked by noise and process them to achieve speech understanding (Rönnberg et al, 2013). This processing may involve executive functions including updating to add relevant information to working memory and inhibition to exclude irrelevant information (McCabe et al, 2010; Sörqvist et al, 2010; Rudner et al, 2011; Rudner and Lunner, 2013). Work to date has shown that CSC is not reliably associated with WMC (Mishra et al, 2013a,b)

Methods

Results

Conclusion