Hearing loss has been something that has been in the back of my mind since I was five-years-old, when I was first diagnosed with it. I knew that sooner rather than later I would have to wear hearing aids, and ended up getting my first pair when I was sixteen-years-old. Our most recent unit about genetics made me wonder about the genetics of hearing loss, knowing that it runs in my family.
The Center for Disease Control found that there are many different explanations for hearing loss in children, some related to genetics, and others related to different factors. While some genes have been linked to hearing loss, the simple answer is that most of the time, scientists do not know what exactly causes hearing loss. However, one gene that has been linked to hearing loss is GJB2. GJB2 is a gene that contains the instructions for a protein called Connexin 26. Connexin 26 plays an important role in development of part of the inner ear, called the cochlea. A mutation to this gene can cause the cochlea to not be formed properly, leading to hearing loss.
At the time I found out I had hearing loss, I did not know all of the implications of this discovery and it turns out that scientists are still discovering all of the implications of hearing loss. Recently, a research team at the University of Cambridge led by Dr. Lorna Halliday found that mild-to-moderate hearing loss in children affects the way their brain develops and how they perceive sound. The structure and function of the auditory system, the part of the brain responsible for processing sound, develops throughout childhood in response to exposure to sound. It has been widely known that in deaf children this part of the brain does not fully develop and instead reallocates parts of the brain to respond to more visual stimuli. Dr. Halliday and her team found that similar developments were occurring in children with mild-to-moderate hearing loss.
In the study, brain activity was recorded with an electroencephalogram (EEG) in children with mild-to-moderate hearing loss in two groups, first children ages eight to twelve, then ages twelve to sixteen. Brain activity compared to children without hearing loss was normal for children in the eight to twelve age group. However, the brain responses of older children with hearing loss were smaller than their normal hearing peers. When the children in the first age group were tested again six years later, their brain activity was similar to those in the older age group during the first study, despite their hearing loss not worsening. Their findings suggest that there is a functional reorganization in the brain as it develops in response to sound. With the new knowledge of some of the effects hearing loss can have on the development of a child’s brain, preventative measures can be taken earlier in life, such as wearing hearing aids.
Wearing hearing aids has proven to protect the brain in other ways too. Hearing aids help to reduce tinnitus, or ringing in the ears, which 30% of people with hearing loss experience. People with hearing loss are at a higher risk of other health issues, but hearing aids have proven to lower these risks. However, only 12% of people diagnosed with hearing loss wear hearing aids. Studies have found that people who wear hearing aids maintain better brain function over time. Hearing loss is a risk factor for dementia, however, dementia risk could be cut by a third if people started wearing hearing aids in mid life. Compared to people who do not wear hearing aids after three years, diagnosis for Alzheimer’s disease dropped 18%, the risk of being diagnosed with anxiety and depression dropped 11%, and the risk of being treated for fall-related injuries dropped by 13% for people who began wearing hearing aids. This can be attributed to the fact that people with hearing loss tend to have less brain stimulation, less social interaction, less balance, and less independence. Along with improving one’s ability to hear, hearing aids help bring back many of the other things hearing loss has taken away by stimulating more brain activity, improving balance, and making it easier to communicate with other people.