Presbycusis, a common type of hearing loss related to aging, has long been associated with an increased risk of cognitive decline. However, the specific biological mechanism connecting these two conditions has remained unclear. Researchers from Tiangong University and Shandong Provincial Hospital, led by Ning Li, have now identified a neurobiological link between hearing loss and cognitive decline.
The team discovered what they call the Functional-Structural Ratio (FSR), which reflects changes in connectivity between certain regions of the brain. Their study found that in individuals with presbycusis, connections involving the putamen and fusiform gyrus—regions important for processing sound and speech—as well as the precuneus and medial superior frontal gyrus—areas involved in memory and decision-making—are diminished within functional brain networks. These reduced connections were directly related to both poorer hearing thresholds and lower scores on tests measuring memory and executive function.
According to the authors, these results indicate that hearing loss involves a coordinated reduction in both brain structure and function. This may contribute to the symptoms seen in affected individuals. Ning Li stated, "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."
