Hearing loss can be a frustrating, socially awkward experience, no matter what age. Here’s guest blogger, Paul Harrison, on some of the latest news about the causes of hearing loss in younger people.
In 2013, a new study was conducted into the causes of early onset hearing loss. It has been proven already that trauma, infection and certain medications can create hearing problems but the one that remains the most common is simple wear and tear on the ear. Over time, the inner parts of the ear deteriorate which leads to age related hearing loss or ‘Presbycusis’.
Scientists wanted to know how someone in their teens or twenties could present with the same hearing loss symptoms as someone much older who would naturally have hearing deterioration. It is common for people over the age of 60 to begin to develop age-related hearing loss but this study was to discover what causes the same wear and tear in much younger people.
Researchers from both the department of biochemistry and molecular biology at Monash University and the otolaryngology department at the University of Melbourne were involved in this study and have observed some very interesting results.
Previous studies into this subject had already shown a specific problem that could be the cause of this type of hearing loss. In 2010, they discovered a genetic mutation within test subjects that provided new information. This study was conducted to investigate this mutation in more depth. An inhibitor was discovered known as SERPINB6.
This inhibitor is essential as it blocks a certain enzyme created naturally by the body which has the ability to destroy proteins. It was found that when this inhibitor was malfunctioning due to the genetic mutation, the rate of deterioration in hearing was greatly accelerated.
Dr Justin Tan of the University of Melbourne, who was the lead author of the study, was quoted as saying,
‘individuals who lack both copies of this good gene were reported to lose their hearing from 20 years of age’.
To support this research, tests were carried out so the results could be examined more clearly. Shortly after birth, infant mice were artificially induced with the mutation and then monitored. At three weeks old, the mice were then tested as this would be the equivalent of a human being reaching their teenage years.
Even at this early stage, all of the mice had begun to exhibit some degree of hearing loss due to the SERPINB6 inhibitor malfunction. Further tests were periodically carried out as the mice developed and the results showed exactly what was predicted. As they grew older, the hearing loss continued to increase, just as it would in a human being who had this condition. The inner ears of the mice were also carefully examined under a microscope and showed that there was definite damage to the tiny sensory hair cells inside.
These hair cells are absolutely essential for normal hearing. As sound enters the ear, it passes over the sensory hair cells and causes them to vibrate. These vibrations are then turned into electrical impulses which travel through the auditory nerve to the brain. The brain takes theses impulses and processes them as the sound we hear.
Mutations that affect the sensory hair cells have been observed before in earlier studies so this was not new information for the researchers. The biggest discovery was the effect that this mutation had on neighbouring cells.
There is an equally important group of cells known as Fibrocytes, which also help to process the electrical signals in the ear. Although damage to these cells had been witnessed before in human beings, it is still very uncommon. This mutation had actually killed off these cells as well, which could potentially be the cause of the accelerated deterioration.
Lead author, Dr Tan, stated,
‘This is an exciting discovery for our hearing because the role of SERPINB6 as an inhibitor is now being unravelled’.
Losing your hearing can be extremely distressing, especially when it happens at a very early age but this research could help to identify, and potentially prevent early onset hearing loss. A significant amount of further research and testing is required before this becomes a realistic possibility but these studies are providing hope that there could be a solution in the future.
Researchers are extremely positive about this discovery as the link between this mutation, SERPINB6 inhibitor and the cell deterioration has provided them with valuable further insight into the genetic causes of hearing loss.
About the Author
Paul Harrison is a hearing specialist and owns his own hearing aid business www.yourhearing.co.uk. He has worked in the hearing aid sector for 20 years at both retailer and manufacturer level and continues to give expert advice to hearing sufferers in the UK as well as blogging on frequent basis.