Abstract
Purpose Hearing loss is associated with changes in brain volume in regions supporting auditory and cognitive processing. The purpose of this study was to determine whether there is a systematic association between hearing ability and brain volume in cross-sectional data from a large nonclinical cohort of middle-aged adults available from the UK Biobank Resource ( http://www.ukbiobank.ac.uk ). Method We performed a set of regression analyses to determine the association between speech reception threshold in noise (SRTn) and global brain volume as well as predefined regions of interest (ROIs) based on T1-weighted structural images, controlling for hearing-related comorbidities and cognition as well as demographic factors. In a 2nd set of analyses, we additionally controlled for hearing aid (HA) use. We predicted statistically significant associations globally and in ROIs including auditory and cognitive processing regions, possibly modulated by HA use. Results Whole-brain gray matter volume was significantly lower for individuals with poorer SRTn. Furthermore, the volume of 9 predicted ROIs including both auditory and cognitive processing regions was lower for individuals with poorer SRTn. The greatest percentage difference (-0.57%) in ROI volume relating to a 1 SD worsening of SRTn was found in the left superior temporal gyrus. HA use did not substantially modulate the pattern of association between brain volume and SRTn. Conclusions In a large middle-aged nonclinical population, poorer hearing ability is associated with lower brain volume globally as well as in cortical and subcortical regions involved in auditory and cognitive processing, but there was no conclusive evidence that this effect is moderated by HA use. This pattern of results supports the notion that poor hearing leads to reduced volume in brain regions recruited during speech understanding under challenging conditions. These findings should be tested in future longitudinal, experimental studies. Supplemental Material https://doi.org/10.23641/asha.7949357.
Highlights
A number of cross-sectional studies have found that acquired hearing loss is associated with smaller volume in the primary auditory cortex (PAC) in Heschl’s gyrus (Eckert, Cute, Vaden, Kuchinsky, & Dubno, 2012; Peelle, Troiani, Grossman, & Wingfield, 2011) and supplementary auditory processing areas in the superior temporal gyrus (STG; Husain et al, 2011; Yang et al, 2014)
Region of interest (ROI) analysis showed that participants with more high-frequency hearing loss had lower gray matter volume in the Te1.0 subregion of the PAC bilaterally accompanied by a greater volume of cerebrospinal fluid, whereas participants with more lowfrequency hearing loss had lower gray matter volume in the Disclosure: The authors have declared that no competing interests existed at the time of publication
Results showed that poorer speech reception threshold in noise (SRTn) was associated with smaller gray matter volume in the STG comparable with the annual hearing-related reduction in STG volume reported by Lin et al (2014) but of a lower order of magnitude in terms of volume difference compared to the effects of age
Summary
A number of cross-sectional studies have found that acquired hearing loss is associated with smaller volume in the primary auditory cortex (PAC) in Heschl’s gyrus (Eckert, Cute, Vaden, Kuchinsky, & Dubno, 2012; Peelle, Troiani, Grossman, & Wingfield, 2011) and supplementary auditory processing areas in the superior temporal gyrus (STG; Husain et al, 2011; Yang et al, 2014). ROI analysis showed poorer hearing (higher pure-tone average threshold in the better ear across the frequencies 1, 2, and 4 kHz) and was significantly associated with lower gray matter volume in the right PAC (areas TE1.0 and TE1.1), and there was a similar but nonsignificant trend in the contralateral region. These findings, together with the functional results, were interpreted as evidence of age-related changes in hearing ability causing reduced gray matter in the auditory cortex. They suggested that, because individuals with hearing impairment miss part of the speech signal, they may rely more heavily on semantic memory to maintain normal communication
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