# Loss of microstructural integrity in left hemispheric white matter tracts is associated with poorer digits in noise understanding

## TL;DR

This study finds that brain changes in certain white matter tracts are linked to difficulty understanding speech in noise among older adults.

## Contribution

The study reveals new associations between speech-in-noise understanding and specific left hemisphere white matter tracts, independent of hearing loss.

## Key findings

- Poorer speech-in-noise understanding is associated with reduced integrity in left inferior fronto-occipital fasciculus and inferior longitudinal fasciculus.
- The association remains strong after adjusting for audibility effects in these tracts.
- Posterior thalamic radiation showed a significant association only before accounting for audibility.

## Abstract

Age-related hearing loss (ARHL) is a prevalent condition among older adults and is regarded as a potentially modifiable risk factor for dementia. Although multiple studies have investigated pure-tone thresholds as a measure for ARHL and its relationship to dementia, the potential role of the central auditory system has received little attention. To address this gap in the literature, this study investigates the relationship between central auditory functioning, assessed using the speech-reception-threshold (SRT) of the digits-in-noise (DIN) test, and the microstructural integrity of white matter tracts in the Rotterdam Study. A total of 1669 participants underwent the DIN test and had diffusion imaging data available. The SRT was found to be significantly associated with the microstructural integrity of the left inferior fronto-occipital fasciculus, inferior longitudinal fasciculus, and posterior thalamic radiation. After accounting for audibility effects, the association with the inferior fronto-occipital fasciculus and the inferior longitudinal fasciculus was even stronger, while the association with the posterior thalamic radiation was no longer significant. These findings suggest that age-related declines in specific brain regions may contribute to difficulties in speech-in-noise understanding among the elderly.

The online version contains supplementary material available at 10.1007/s11357-025-01707-5.