Research Shows Potential to Reverse Noise-Induced Hearing Loss

Researchers from Harvard Medical School have teamed up with researchers from the University of Michigan’s Kresge Hearing Research Institute to produce a protocol that reverses noise-induced hearing loss in mice.

Noise exposure has resulted in about 26 million Americans aged 20-69 experiencing high-frequency hearing loss. Aging is also another reason for hearing loss. It affects about 30% of adults aged 65-74 and 47% of adults over age 75.

Breast Cancer Drug for Hearing Loss?

Researchers used the breast cancer treatment drug Tamoxifen to boost production of the protein NT3. NT3 is used by the body to send signals from the ear to the brain. It establishes the connection between the ear’s hair cells and nerve cells. The connection is referred to as the “ribbon synapse.” If you have ever had a problem making out the voice of the person next to you in a crowded room, then you have felt the effects of reduced ribbon synapses.

This connection can be damaged by repeated noise exposure or just the normal aging process. When the connection is degraded, hearing loss is the result.

After treatment with Tamoxifen, hearing was then tested with the auditory brainstem response (ABR) test that is used to test hearing in humans. The results were astonishing! In just two weeks, the mice that had boosted NT3 production regained their hearing, compared with mice that did not have additional NT3 production.

Gabriel Corfas, a lead researcher on the project says, “It has become apparent that hearing loss due to damaged ribbon synapses is a very common and challenging problem, whether it’s due to noise or normal aging. We began this work 15 years ago to answer very basic questions about the inner ear, and now we have been able to restore hearing after partial deafening with noise, a common problem for people. It’s very exciting.”

The Potential to Reverse Hearing Loss

Now that the researchers have established the connection between NT3 production and the reversal of hearing loss they will begin to find ways to increase NT3. Ideally, they will identify a drug that will produce sufficient NT3 to return hearing. The drug would be given until hearing was restored and then could be discontinued.

Gabriel Corfas says he already has some drugs in mind. Stay tuned for more news!