Changes in the default mode networks of individuals with long-term unilateral sensorineural hearing loss

- Hearing loss contributes to changes of functional connectivity.
- Enhanced connectivity is related to decease in the shortest path length.
- Shorter characteristic path length was found in some cognition-related brain regions.
- Left hearing loss affects the DMN more than the right hearing loss does.

Hearing impairment contributes to cognitive dysfunction. Previous studies have found changes of functional connectivity in the default mode network (DMN) associated with cognitive processing in individuals with sensorineural hearing loss (SNHL). Whereas the changes in the DMN in patients with long-term unilateral SNHL (USNHL) is still not entirely clear. In this work, we analyzed resting-state functional magnetic resonance imaging (fMRI) data and neuropsychological test scores from normal hearing subjects (n = 11) and patients (n = 21) with long-term USNHL. Functional connectivity and nodal topological properties were computed for every brain region in the DMN. Analysis of covariance (ANCOVA) and post hoc analyses were conducted to identify differences between normal controls and patients for each measure. Results indicated that the left USNHL presented enhanced connectivity (p < 0.05, false discovery rate (FDR) corrected), and significant changes (p < 0.05, Bonferroni corrected) of the nodal topological properties in the DMN compared with the control. More changes in the DMN have been found in the left than right long-term USNHL (RUSNHL). However, the neuropsychological tests did not show significant differences between the USNHL and the control. These findings suggest that long-term USNHL contributes to changes in the DMN, and these changes might affect cognitive abilities in patients with long-term USNHL. Left hearing loss affects the DMN more than the right hearing loss does. The fMRI measures might be more sensitive for observing cognitive changes in patients with hearing loss than clinical neuropsychological tests. This study provides some insights into the mechanisms of the association between hearing loss and cognitive function.

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