Summary: For years, scientists have observed a strong correlation between age-related hearing loss (presbycusis) and cognitive decline, but the biological mechanism connecting the two has remained elusive. Researchers have now identified a specific “bridge” known as the Functional-Structural Ratio (FSR). This ratio measures how well specific brain regions—those responsible for sound, speech, memory, and decision-making—remain integrated into functional networks.
The study reveals that as hearing worsens, the brain undergoes a coordinated decline in both structure and function, particularly in areas like the putamen and precuneus. This discovery could allow doctors to use brain scans to identify individuals at the highest risk for dementia simply by monitoring changes in their hearing-related neural integrity.
Key Facts
- The Biological Bridge: The Functional-Structural Ratio (FSR) is a new biomarker that links the severity of hearing loss to the extent of cognitive impairment.
- Affected Regions: The study highlighted the putamen and fusiform gyrus (sound/speech) and the precuneus and medial superior frontal gyrus (memory/decisions) as key areas that become disconnected in those with hearing loss.
- Structural-Functional Coupling: Hearing loss involves a simultaneous breakdown of both the physical brain tissue and the electrical communication networks between these regions.
- Predictive Power: Changes in the FSR correlate directly with poor performance on memory and executive function tests, suggesting it could be used to predict dementia risk.
- Preservation is Protection: The findings emphasize that maintaining hearing health may be one of the most effective ways to protect overall brain integrity during aging.
Source: SfN
Presbycusis is a prevalent form of age-related hearing loss that also hinders speech recognition. While scientists have linked hearing loss to an increased risk of cognitive decline, the biological “bridge” between the two has remained unclear.
New from eNeuro, researchers at Tiangong University and Shandong Provincial Hospital, led by Ning Li, explored the link between these symptoms in people.
The researchers identified a specific neurobiological link between hearing loss and cognitive decline called the Functional-Structural Ratio (FSR).
They found that the putamen and fusiform gyrus (involved in processing sound and speech) and the precuneus and medial superior frontal gyrus (involved in memory and decision-making) become less connected to functional brain networks in those with presbycusis.
These reduced connections to networks were directly associated with worse hearing thresholds and poorer performance on memory and executive function tests.
According to the authors, these findings suggest that hearing loss involves a coordinated decline in both brain structure and function, which may contribute to the symptoms of the disorder.
Says Li, “The most important takeaway is that preserving hearing health may protect brain integrity. Because changes in the FSR correlate with both hearing loss and cognitive decline, this ratio could eventually serve as a biomarker—a tool for doctors to identify who is at the highest risk for dementia simply by looking at their brain scans.”
Key Questions Answered:
A: When the brain stops receiving clear sound signals, the areas responsible for processing that information begin to “wither” or disconnect from the rest of the brain’s networks. Because these regions are also involved in memory and decision-making, the impact spreads, eventually affecting overall cognitive function.
A: FSR stands for Functional-Structural Ratio. Think of it as a health score for your brain’s “wiring.” It measures whether the physical structure of your brain and its electrical activity are staying in sync. In hearing loss, this ratio drops, signaling that the brain is starting to reorganize in a way that leads to cognitive decline.
A: While this study focuses on identifying the link, the lead researcher notes that “preserving hearing health may protect brain integrity.” This suggests that keeping the auditory system active—whether through protection or aids—could help keep those vital neural networks connected.
Editorial Notes:
- This article was edited by a Neuroscience News editor.
- Journal paper reviewed in full.
- Additional context added by our staff.
About this auditory neuroscience and dementia research news
Author: SfN Media
Source: SfN
Contact: SfN Media – SfN
Image: The image is credited to Neuroscience News
Original Research: Closed access.
“Functional–Structural Coupling: Brain Reorganization in Presbycusis is Related to Cognitive Impairment” by Xiaojie Li, Weilong Fu, Yao Wang, Yuting Gao, Jinhai Wang, Jing Yang, Longji Xu, Fei Gao, Xiao Li and Ning Li. eNeuro
DOI:10.1523/ENEURO.0294-25.2026
Abstract
Functional–Structural Coupling: Brain Reorganization in Presbycusis is Related to Cognitive Impairment
Presbycusis, a prevalent neurodegenerative disorder, is characterized by a decline in speech recognition ability. Recent studies have linked presbycusis with cognitive impairments across multiple domains. However, the underlying neurobiological mechanisms between presbycusis and cognitive impairments remain unclear.
We assessed pure-tone audiometry thresholds (PTA), speech recognition thresholds (SRT), and cognitive abilities in individuals with presbycusis (24 males and 31 females) and healthy controls (23 males and 32 females).
Using magnetic resonance imaging techniques, we calculated the amplitude of low-frequency fluctuations (ALFF) as a measure of functional characterization and gray matter volume (GMV) as a measure of structural characterization.
Based on ALFF and GMV, we calculated Functional-Structural Ratio (FSR) to measure the functional-structural coupling. Significant correlations between GMV atrophy and ALFF changed in the putamen, fusiform gyrus, precuneus, and medial superior frontal gyrus in presbycusis group, and these changes were significantly associated with the increase in PTA and SRT.
The FSR reduction in the FFG, precuneus, and medial superior frontal gyrus were also significantly associated with the increase in PTA and SRT. Moreover, it was also significantly correlated with lower scores on the Montreal Cognitive Assessment (MoCA) and the Auditory Verbal Learning Test (AVLT), as well as the prolonged time in the Trail Making Test (TMT-A).
Presbycusis involves coupled structural atrophy and functional decline in auditory and higher-order cognitive regions. Crucially, reduced FSR correlates with both worsening hearing thresholds and cognitive impairment. This highlights FSR as a key neurobiological link between hearing loss and cognitive decline.
This research provides a novel basis for early screening and dynamic monitoring of presbycusis-related cognitive impairment.
Significance Statement
This study reveals that age-related hearing loss (presbycusis) involves coupled structural atrophy and functional decline in key brain regions like the fusiform gyrus and putamen.
We introduce the Functional-Structural Ratio (FSR) as a novel biomarker showing that reduced brain functional-structural coupling correlates with both worsening hearing thresholds and cognitive impairment.
This provides the first direct neurobiological evidence linking hearing loss to cognitive decline via shared neural reorganization. FSR offers a potential tool for early screening and monitoring of dementia risk in presbycusis, highlighting that preserving hearing health may protect brain integrity.
These findings advance our understanding of how sensory decline drives neurodegeneration.
