Helping tinnitus sufferers

A quarter of the UK population experiences occasional tinnitus and for over three and a half million people it is a permanent problem. 300,000 people are so badly affected by tinnitus that they are unable to lead a normal life.

Deafness Research UK has researched the underlying causes of this distressing and debilitating condition.

We funded a programme of research into the role of chemicals, known as neurotransmitters, used by the ear and the auditory nerve to transmit signals to the brain. The neurotransmitter used by the hearing nerve at the major connections in the brainstem is an amino acid called glutamate.

The sensory cells of the ear itself are also thought to use glutamate at the first connection in the auditory pathway. Glutamate is known to be an effective chemical for sending rapid signals but, if released in excessive amounts, it is also known to cause damage to the next nerve cell in the chain. It is therefore possible that, as well as being implicated in hearing loss, inappropriate glutamate levels in the ear are one potential cause of tinnitus. The researchers found that a special transporter molecule which removes glutamate, GLAST, normally found in the brain is also present in the ear.

They also investigated the possibility that, if the GLAST “mop up” system fails, resulting in a glutamate build up, it could result in inappropriate signals being sent along the hearing nerve causing tinnitus or other hearing problems.