Mary is a 65-year-old nurse.  She is in excellent health, is rarely exposed to loud noises and does not report a family history of hearing loss.  Yet a recent hearing test revealed Mary has a mild to moderate high frequency sensorineural hearing loss in both ears.

Q:  What caused Mary’s hearing loss?

A:  Scientists are investigating the causes of age related hearing loss.  Their findings may help to explain why older adults who fit Mary’s description experience a loss of hearing sensitivity.

A potential cause of age related hearing loss is oxidative stress that occurs inside cells as we age.  Oxidative stress is defined as an imbalance between the creation of reactive oxygen species (free radicals) and antioxidant defenses in a cell (Betteridge, 2000).  In other words, free radicals are being produced faster than the body can produce antioxidants to get rid of them.

Over time, oxidative stress damages the mitochondrial DNA inside cells.  Remember that mitochondria are structures inside cells responsible for changing food energy into a form the cell can use (NIH Genetics Home).  If mitochondrial DNA is damaged, errors can be present when new cells are created, and over time these genetic errors add up.  The result is mitochondria that do not function properly inside the cells of the auditory system (Yamasoba et al., 2013).

Q:  Can I minimize age related hearing loss?

A:  There are ways to minimize risk factors for hearing loss.  A recent study by Yamasoba (2013) and colleagues suggests potential risk factors for age related hearing loss.  These include:

• aging of the cochlea
• noise exposure
• health issues such as smoking and atherosclerosis (build-up of plaque in the arteries, NIH)

While you cannot control your genetic factors or aging itself, you can minimize your noise exposure and make healthy choices to help protect your hearing.

References

Betteridge, D.J. (2000). What is oxidative stress? Metabolism, 49: 3-8.

http://ghr.nlm.nih.gov/mitochondrial-dna

https://www.nhlbi.nih.gov/health/health-topics/topics/atherosclerosis

Yamasoba, T., Lin, F. R., Someya, S., Kashio, A., Sakamoto, T., & Kondo, K. (2013). Current concepts in age-related hearing loss: epidemiology and mechanistic pathways. Hearing research, 303, 30-38.

Image courtesy of Sira Anamwong at FreeDigitalPhotos.net