This is a Discovery Research Grant awarded to Professor Sven Vanneste at Trinity College Dublin, Ireland, in 2024.
Background
Tinnitus is the perception of sound in the absence of any external sound source. It is commonly described as a ringing, buzzing, hissing, whistling or humming sound in the head or ears. It is very common – around 1 in 7 adults in the UK live with persistent tinnitus. Many more experience tinnitus occasionally.
Tinnitus can have a severe impact on someone’s quality of life, causing anger, frustration, problems sleeping, depression and anxiety. Currently, the most effective treatments for tinnitus are psychological management approaches which aim to reduce tinnitus-related distress. There is no cure for tinnitus, and to date, no treatment that achieves a consistent long-term reduction of the tinnitus sensation.
Many researchers think that the brain creates a model of its environment in which it is constantly predicting what is happening, or about to happen, enabling us to be ready to respond quickly to situations as they arise. When incoming information from the outside world conflicts with this model (such as perceiving a sound in the absence of any external source), the brain’s attention is drawn to resolving this conflict.
In the case of tinnitus, if the brain has enough evidence that perceiving tinnitus is the best way to resolve the conflict, then the person will become more aware of their tinnitus. The stronger the ‘evidence’ the brain has, the louder the tinnitus sound will be and the more importance the brain will place on it – this causes the distress a person experiences as a result. Over time, if there is no new information to challenge the perception of tinnitus, the brain makes perceiving tinnitus its new default state.
Aims
In this project, the researchers will try to break the association between the perception of tinnitus and distress by re-training the brain to pay attention to actual sounds over tinnitus and un-learn tinnitus as the default state. They will try to shift the brain’s prediction closer to perceiving “silence” in the absence of an external sound (the normal default state).
They will investigate whether a new treatment that combines non-invasive electrical stimulation of a part of the brain called the occipital nerve (located at the back of the head) with carrying out an auditory task every day for seven days can suppress tinnitus.
Participants will be randomly assigned to one of four groups – real stimulation/active listening, real stimulation/passive listening, control (sham) stimulation/active listening and control (sham) stimulation/passive listening.
Active listening involves performing the auditory task and ignoring visual cues and passive listening involves performing a visual task and ignoring auditory cues. To measure how effective their treatment is, the researchers will record participants’ assessment of their tinnitus loudness and distress before, immediately after and 28 days after the treatment has ended.
The rationale is that active sound stimulation reduces the tinnitus information provided to the brain and suppresses the loudness of the tinnitus sound. By asking the brain to allocate attention to the task instead of the tinnitus sound, the treatment should also reduce the associated distress. Stimulation of the occipital nerve should enhance these effects so that the treatment has a lasting effect.
Benefit
This treatment targets tinnitus by helping the brain to un-learn old patterns and learn new patterns of paying attention to sounds other than the tinnitus sound. Non-invasive electrical nerve stimulation is cheap, safe, reliable and user-friendly and could be developed into a home-based treatment regime. If successful, future studies will investigate how this treatment could be used in conjunction with other treatments to provide maximum benefit to people with tinnitus.