What Is Presbycusis

Presbycusis is age related hearing loss. It usually affects both ears and becomes more common after age 60. Experts estimate that nearly two thirds of adults over 70 experience some level of hearing loss.

This condition mainly affects the ability to hear high frequency sounds such as “ch,” “f,” and “p.” Over time, this can make speech harder to understand, especially in noisy environments.

For years, scientists have known that hearing loss increases the risk of cognitive decline. However, the exact reason behind this connection has remained unclear.

What Did the Study Examine

The research included 110 adults aged 50 to 74. Among them, 55 participants had presbycusis, while 55 had normal hearing.

The group with hearing loss included:
35 with mild hearing loss
19 with moderate hearing loss
1 with severe hearing loss

Researchers used magnetic resonance imaging to examine brain structure and activity. Participants also completed hearing tests and cognitive assessments.

To better understand how brain structure and function interact, the team introduced a new measure called the Functional Structural Ratio, or FSR.

What Is the Functional Structural Ratio

The Functional Structural Ratio combines two brain measurements:

Brain activity measured using amplitude of low frequency fluctuations
Gray matter volume measured to assess brain structure

The researchers calculated FSR by dividing brain activity by gray matter volume in specific regions.

This allowed them to see how well brain structure and function were working together.

Key Findings

People with worse hearing showed lower FSR scores in certain brain regions. Lower FSR was also linked to poorer performance on memory, learning, and decision making tests.

The affected brain areas included:

The putamen and fusiform gyrus, involved in sound processing
The precuneus and medial superior frontal gyrus, involved in memory and decision making

Importantly, reduced FSR in these areas was connected to both worsening hearing and cognitive impairment.

Researchers describe this shared decline as a possible biological bridge between hearing loss and dementia risk.

Why This Matters

This study is the first to examine how structural shrinkage and functional decline occur together in people with age related hearing loss.

While the research cannot prove whether hearing loss causes brain changes or whether brain changes lead to hearing loss, it strengthens the evidence that the two are closely connected.

Experts believe that identifying a measurable marker like FSR could help doctors detect dementia risk earlier.

If validated in future studies, FSR may serve as a biomarker. Doctors could potentially assess dementia risk in people with hearing loss by analyzing brain scans before noticeable cognitive symptoms appear.

Can Treating Hearing Loss Help Protect the Brain

Specialists note that treating hearing loss early may improve cognitive outcomes.

Hearing aids and cochlear implants can enhance communication. Improved hearing reduces social isolation, depression, and anxiety, all of which are risk factors for cognitive decline.

Untreated hearing loss, on the other hand, may lead to reduced social interaction, emotional distress, and a greater likelihood of memory problems over time.

The Takeaway

The study highlights an important message: protecting hearing health may help protect brain health.

As researchers continue to explore the Functional Structural Ratio, early hearing assessment and treatment may become a more important part of dementia prevention strategies.