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

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.