Speech Recognition Deficits in Presbyacusis: Links to Cortical Structural and Functional Alterations.

OBJECTIVE: To characterize speech recognition in presbyacusis and its associated neurophysiological and cortical structural features, and to explore structure-function-behavior relationships within the presbyacusis phenotype. METHODS: Thirty elderly patients with presbyacusis(HI) and thirty-three healthy young controls(NH) completed a behavioral task involving Putonghua monosyllabic word recognition. Additionally, mismatch negativity (MMN) responses using the oddball paradigm to assess neurophysiological sensitivity, and acquired 3D T1-weighted MRI combined with Freesurfer to quantify cortical thickness (CTh) in six auditory-related regions of interest (ROIs) were recorded. Between-group differences were assessed, and exploratory associations were examined within the HI group; key associations were further evaluated using hierarchical regression adjusting for sex, age, and pure-tone average (PTA). RESULTS: The HI group exhibited significantly poorer speech recognition performance, with prolonged MMN latency and increased amplitude compared to the NH group. CTh was generally thinner (except for the right supratemporal gyrus), with a left-hemisphere bias in the planum polare (PP). Within the HI group, exploratory unadjusted correlations suggested associations of speech recognition rate maximum (SRRmax) with MMN amplitude and right heschl's gyrus (HG) CTh; however, after adjustment for sex, age, and PTA, MMN amplitude and right HG CTh were not significant predictors, and adding these predictors did not improve model fit, whereas PTA remained independently associated with SRRmax. However, no significant associations were found between MMN features and the anatomical characteristics of the ROIs. CONCLUSIONS: Presbyacusis is associated with altered speech recognition, neurophysiological responses, and auditory-related cortical structure compared with young controls. Within the HI group, peripheral hearing thresholds accounted for a major proportion of variance in speech recognition, while MMN/MRI associations observed in exploratory analyses were attenuated after covariate adjustment, warranting replication in larger and better age-matched cohorts.