Brain Biomarker Links Hearing Loss to Cognitive Decline and Dementia Risk
Researchers have identified a specific neurobiological link between age-related hearing loss and cognitive decline through a new biomarker called the Functional-Structural Ratio, which could help doctors predict dementia risk from brain scans.
Researchers at Tiangong University and Shandong Provincial Hospital have identified a specific neurobiological link between hearing loss and cognitive decline called the Functional-Structural Ratio (FSR). The discovery, published in eNeuro, reveals the biological "bridge" that has long remained unclear despite scientists linking hearing loss to an increased risk of cognitive decline.
Presbycusis is a prevalent form of age-related hearing loss that also hinders speech recognition. The researchers 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. The FSR measures how well specific brain regions—those responsible for sound, speech, memory, and decision-making—remain integrated into functional networks. As hearing worsens, the brain undergoes a coordinated decline in both structure and function, particularly in these key areas.
"The most important takeaway is that preserving hearing health may protect brain integrity," the lead researcher stated. "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."
The study reveals that hearing loss involves a simultaneous breakdown of both the physical brain tissue and the electrical communication networks between these regions. Changes in the FSR correlate directly with poor performance on memory and executive function tests, suggesting it could be used to predict dementia risk. The findings emphasize that maintaining hearing health may be one of the most effective ways to protect overall brain integrity during aging.