Study Examines Ways to Protect Against Acquired Hearing Loss

With a new five-year, $3.2 million grant from the National Institute on Deafness and Other Communications Disorders, researchers at Case Western Reserve University and Mass Eye and Ear will study what causes acquired hearing loss (AHL) and seek new ways to protect against it.

AHL is among the most common health conditions affecting older adults, according to the Centers for Disease Control and Prevention. Although hearing aids can help, AHL has no known cure and, in many cases, scientists are still unsure of its exact cause.

AHL significantly impacts quality of life, leading to increased social isolation, depression and cognitive decline. Untreated hearing loss is associated with a higher risk of dementia, with even mild untreated hearing loss doubling the risk.

“We anticipate that if we are successful, this could point to new strategies to preserve human hearing by regulating mitochondrial calcium levels,” said Ruben Stepanyan, assistant professor in the Department of Otolaryngology at Case Western Reserve University School of Medicine.

Understanding hearing loss

An important factor in hearing is the health of cochlear hair cells—sensory cells in the inner ear that detect sound vibrations and send electric signals to the brain. These cells are packed with mitochondria, or microscopic energy-producing components.

Hearing loss may result from damage caused by malfunctioning mitochondria, according to previous peer-reviewed research. Hair-cell health depends on balanced calcium levels regulated, in part, by mitochondria. Loud noises can cause calcium levels to rise too high, stressing the cochlear hair cells.

This study will examine how calcium overload from noise exposure might damage cochlear hair cells contributing to hearing loss and identify novel therapeutic targets to treat it.

Researchers will use a particular type of mouse models more prone to calcium overload and early hearing loss to evaluate how overstimulation from loud sounds affects the structure and function of cochlear hair cells.

They will use advanced three-dimensional imaging technology—along with novel machine-learning-based 3D data analysis approaches—to examine the structure of mitochondria in these cells to understand how they change under stress.

Researchers will then test whether preventing calcium overload in mitochondria can protect hearing by testing other types of mouse models with reduced mitochondrial calcium to learn if they may be more resistant to noise damage.

“The ultimate goal is to find ways to prevent hearing loss related to noise exposure and aging, which could help millions of people protect their hearing as they age,” said Artur Indzhykulian, assistant scientist at Mass Eye and Ear’s Eaton-Peabody Laboratories and assistant professor of otolaryngology at Harvard Medical School.

Article originally appeared on CWRU