Healing age-related hearing loss

The study of the developing inner ear offers molecular clues to understand ageing

Hearing loss is a frequent companion to ageing and we almost all have some experience of it, either personally or through an aged relative. It is the second most common cause of disability in older people, affecting about half of those aged over 60. And more than just sounds are lost to the person, says Dr Isabel Varela-Nieto, who leads a team of neurobiologists at the Consejo Superior de Investigaciones Científicas in Madrid, Spain. 

Dr Varela-Nieto has personal experience of how hearing loss can impact on elderly relatives.  “There is a strong link between not being able to communicate and to suffer from cognitive decline,” she says. When a person loses their hearing it can negatively affect the way they live their lives, their experiences and ultimately the health of their brain.

“If you can’t communicate then the human brain isn’t going to be working properly. You might lose out on some TV, or not enjoy going out to the cinema or to concerts, you no longer enjoy conversations with a few people, and so you become more isolated. That, together with ageing, makes the situation worse,” says Dr Varela-Nieto.

The Spanish scientist is heading a new project – TARGEAR – to set preclinical studies of age-related hearing loss in motion. She will help create lab models of human hearing loss using mice; these are special mice with one or both copies of critical genes for hearing turned off.  She will study how diet and other factors affect such animals, but scientists in this project will also attempt to restore hearing using molecules that have shown some potential to help.

The French biotech company Affichem has a molecule with potential for treating acute hearing loss, but it will now be tested also for age-related hearing loss. “We are trying to identify targets for human IGF-1 [insulin-like growth factor 1) that may have potential to prevent or cure hearing loss,” Dr Varela-Nieto explains. She hopes the project may move some of their molecules closer to tests in people. The project will also try to combine molecules with technology by Austrian company MED-EL.

Dr Varela-Nieto is passionate about the need for stronger links between gerontologists who look at the health of seniors and audiologists concerned with hearing difficulties. “They are often too far apart and they should be getting in closer contact because communication is so important,” she says. “From sounds you get not only information but also feelings and lots of rewarding things from sounds you like, or from the feeling that someone is talking to you warmly. You lose a lot when you cannot hear.”

 A second aim of the TARGEAR project is to build up and support young researchers in labs, in hospitals and in companies and to improve the way knowledge in the field of hearing loss is shared. “We think that in the short-term Europe will need more professionals with knowledge in ageing but also in age-related hearing loss, because this is something that will improve the quality of life for people,” says Dr Varela-Nieto. 

Worldwide, 278 million people are estimated to have moderate to profound hearing loss.  There is no way of restoring lost hearing yet, but hearing aids can help make up for loss.  Still, prevention and treatment of hearing loss deserves attention. 

“I’ve seen the effects of hearing loss in close relatives. I’ve also seen people with age-related hearing loss suffering accelerated cognitive decline and I think it is something that deserves to be studied in depth,” says Dr Varela-Nieto.