ANN ARBOR, MI - At a time when longer life spans are leading to a rapid increase in the number of people with age-related hearing loss, a new federal grant will help University of Michigan Health System researchers understand the causes of hearing loss as people age and possibly the ways of lessening or preventing the damage that leads to it.

The National Institute on Aging – part of the National Institutes of Health – has awarded UMHS researchers with a five-year, nearly $6.9 million grant for three inter-related projects that aim to increase researchers' understanding of aging processes in the inner ear.

Age-related hearing loss, or presbycusis, is a major health concern – one that affects an increasing number of people as they reach older ages. It can start when people reach their 50s and approximately 44 percent of people suffer from a significant hearing loss by age 69. This number rises to 66 percent by age 79 and skyrockets to 90 percent after age 80.

The consequences are vast and potentially devastating, both for people suffering from hearing loss and for society at large, says Jochen Schacht, Ph.D., professor of biological chemistry in otolaryngology at the U-M Medical School and director of UMHS's Kresge Hearing Research Institute. Loss of productivity, social isolation and a significantly lower quality of life can result when communication is impaired, he says.

“Age-related hearing loss is an issue that catches up with all of us,” says Schacht, the principal investigator on the grant. “It affects not only the people suffering the hearing loss, but also their families and friends who struggle to find ways of communicating with them.”

The three projects funded by the grant are:

Project 1 , “Antioxidant and homeostatic pathways in the aging cochlea,” directed by Schacht with Su-Hua Sha, M.D., associate director of Kresge's Biochemistry Laboratory, as co-investigator. This project will examine age-related injuries to the inner ear, and whether altering the antioxidant levels in an animal's diet can influence the progression of age-related hearing loss.

Project 2 , "Stress pathways in the aging cochlea," directed by Margaret Lomax, Ph.D., director of Kresge's Molecular Biology Laboratory, with co-investigators Richard Altschuler, Ph.D., director of Kresge's Auditory Anatomy Laboratory, and David Kohrman, Ph.D., director of Kresge's Molecular Genetic Laboratory. This project will analyze responses of mice to stress during aging and will provide a better understanding of the role of the protection provided by stress pathways.

Project 3 , “Genetic analysis of stress resistance and loss of hearing,” directed by Richard Miller, M.D., Ph.D., professor of pathology at the U-M Medical School, associate director of the Department of Geriatrics and senior research scientist at the Institute of Gerontology. His co-investigators are Andrzej Galecki, M.D., Ph.D., associate research scientist at the Institute of Gerontology , and David Burke, Ph.D., a ssociate professor of human genetics at the U-M Medical School and associate research scientist for the Institute of Gerontology . They will explore the characteristics of aging in mice of a novel four-way genetic cross that will permit an assessment of the extent to which changes in hearing related to age are molded by the genetic, cellular and hormonal factors that time the aging process in mice.

The three projects could lead to a far-reaching expansion in our understanding of age-related hearing loss, says Miller, co-principal investigator on the overall grant.

“The three component projects within this program have a high likelihood of providing interesting new insights into the ways in which different stress pathways affect the aging cochlea leading to age-related hearing loss,” Miller says. “If we learn more about how genes affect late-life hearing loss, for example, we have the potential to delay hearing loss in people as they age, or even prevent it altogether.”

Others involved in the research will be David Dolan, Ph.D., director of Kresge's Auditory Physiology Laboratory, who will evaluate the auditory function of mice, and biostatistician Shu Chen of the U-M School of Public Health, who will oversee data collection and analysis to integrate results from all projects.

The Kresge Hearing Research Institute is part of the U-M Medical School's Department of Otolaryngology. The groundbreaking research conducted at the Institute involves behavior, morphology, physiology, molecular biology and genetics, bioengineering, pharmacology, and the biochemistry of hearing and deafness. For more information, go to www.khri.med.umich.edu/.

The Geriatrics Center at the University of Michigan Health System is consistently ranked one of the best in the country. In the past year, the Turner Geriatric Clinic – the busy outpatient program of the Geriatrics Center – drew more than 20,000 visits. For more about the Geriatrics Center , go to www.med.umich.edu/geriatrics/.

Written by Katie Gazella

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