An estimated 10 to 40 million adults will show some signs of noise-induced hearing loss (NIHL), and with the number of those suffering from hearing loss expected to double within the next thirty years, understanding the causes and treatment options for NIHL could help reduce that discouraging forecast. Everyone is affected by similar levels of noise exposure in different ways, with some being more resistant or susceptible to the loud environment around them, but a new study conducted by the University of Rochester suggests that genetics may be the reason why. Whether you are exposed to dangerous volumes in the workplace, the gym, or at a concert, new research suggests your genes may make you more vulnerable to hearing loss than others.
Symptoms of NIHL
Noise-induced hearing loss can present itself in different ways depending on the person, further suggesting that susceptibility may vary across different populations. Exposure to loud noises can lead to a temporary reduction of auditory thresholds, while dramatically excessive volumes like jet engines can lead to a permanent shift in your auditory threshold, minimizing the range of sounds the human ear can hear. Tinnitus, that pesky ringing many experiences after a loud night out, is also a common result of damaging noise exposure.
But trouble hearing and a bothersome buzzing are not the only changes experienced as a result of noise-induced hearing loss. Symptoms of NIHL can be correlated to injuries of specific structures inside the ear. The tympanic membrane, an extremely thin and fragile part of the ear that vibrates when impacted by sound waves, is used to transfer acoustic waves to the inner ear but excessive blasts of volume can destroy this structure, as well as hair cells inside the cochlea that are needed to continue the hearing process.
How Genetics Play Their Part
With such a complex process, how do genetics play a role? Dr. Patricia White, an associate professor at the Ernest J. Del Monte Institute for Neuroscience at the University of Rochester, had decided to research just how different gene variants may affect animal models when exposed to dangerous volumes. Animal models were chosen due to the difficulty presented when studying NIHL in humans, due to different health backgrounds and lifestyle choices. Over 140 gene variants have been linked to hearing loss, with only 34 variants being identified as associated with human NIHL.
The team at the University of Rochester had studied the results of noise exposure in mice with a gene variant called FOX03, chosen due to its overrepresentation in human populations with occupational NIHL. What they had concluded was striking. “We found that mice with no functional copies of FOXO3 are strikingly susceptible to NIHL,” explains Dr. White “They have greater threshold shifts, poorer recovery, and more outer hair cell death compared with their wild-type littermates.” From these results, Dr. White hopes to identify further individual susceptibility to NIHL and help prevent this growing problem, concluding that “individuals may have differential susceptibility to NIHL, and some of these differences are likely due to variants in specific genes.”
If you are showing symptoms of noise-induced hearing loss, it may be time to speak to a hearing health professional to discuss treatment options or preventative measures you can take to protect your hearing.