Poorly discerning the words of one’s interlocutor in a noisy environment is one of the most common annoyances linked to aging. Its effects sometimes appear as early as the thirties.
Often associated with hearing loss, this problem actually has more to do with the decline of the brain in language processing, according to Pascale Tremblay, full professor in the Department of Rehabilitation at Laval University.
To tackle this phenomenon, the Dre Tremblay and Valérie Brisson, a doctoral student in rehabilitation sciences, used transcranial magnetic stimulation (TMS), a technology that activates certain areas of the brain associated with language. Their recent study published in the journal Brain and Language suggests that TMS could be of great help to people who have poor hearing when ambient noise is high.
News spoke with Pascale Tremblay.
Why do we have more difficulty communicating in a noisy environment as we get older?
This is a big question without a definitive answer for now. Communication is complex and made up of several components: hearing, linguistic processing and the cognitive functions of the brain. With age, the difficulties can be explained by different factors or even by the combination of these.
For a long time, this question was approached from the angle of a hearing problem, and it was thought to be solved with the help of hearing aids, without success. On our side, we opted instead for multidisciplinarity, emphasizing the linguistic aspect. Hearing sounds well is not enough to understand someone’s words. It is necessary to be able to process the data received and to decode them. It is these stages of linguistic processing that lead to the understanding of language.
How big can the problem get?
Unfortunately, the consequences of communication difficulties are greatly minimized. Several studies have found affected individuals to have concerns about self-confidence, self-esteem and the desire to communicate. People who do a lot of rehearsing end up feeling like they’re bothering others. In many cases, there are strategies to avoid noisy situations or places, but this often comes with withdrawal from social activities.
And at the other end of the spectrum, some people are less open to adapting their speech to those who have difficulty understanding. Sometimes it is even inferred that they have cognitive impairment, which is not the case. In the end, the people affected are excluded or exclude themselves.
What is Transcranial Magnetic Stimulation (TMS) and how could it help treat this type of problem?
Transcranial magnetic stimulation has been around since the 1980s. It is already recognized as a treatment for certain diseases such as refractory depression or auditory hallucinations, and it is being tested for many neurological or psychiatric diseases.
Thanks to a small device that we hold in our hand and that we apply to the person’s head, we send small impulses to well-defined areas of the brain to stimulate cerebral activity there. The aim is to make the brain more reactive in the given region, which facilitates the processing of information.
For example, in our latest study, we stimulated the ventral premotor cortex, a region of the left frontal lobe that is involved in both the perception and production of speech sounds.
In our studies, our patients were given [NDLR : 34 sujets de 32 à 79 ans] a magnetic resonance imaging (MRI) examination to obtain images of their brain and target the desired region. This allows us to pair our stimulator in real time with the image of the patient’s brain.
To measure the effect, before and after the TMS they are made to do a series of tests which consist of identifying very similar syllables among a background sound where several human voices intertwine. What is very interesting is that the people who improved the most from one test to the next were the ones who had the most difficulty at the start.
It is a very focused stimulation: only a few centimeters of the brain are activated at a time. The protocols we use at the moment are very fast: they last three minutes, for an effect of about an hour. As we are not at the clinical trial stage, we are not looking for long-term effects. We are just trying to see if it works and to find the best regions to stimulate.
Your study claims that this TMS protocol improves the ability to understand in a noisy environment by 5%. How do you interpret this result?
I find this result extremely positive, since we managed to have a fairly stable gain from one person to another. With my team, we continue to work to replicate the study and increase the effect of TMS. A 5% improvement is interesting, but not enough to initiate a clinical trial. We would like to go to 15% or 20%. The next step will be to launch a more intense protocol with stimulation over several days to aim for long-term effects.
What is interesting in our study is that older people reacted just as much as younger people to stimulation. We didn’t expect that. It shows that the brain retains its plasticity over the years.
In the future, could we see such treatments accessible to the general public?
If the tests are conclusive, I believe it is possible within 10 years. The stimulation is not very difficult to do and the device is relatively affordable. They are methods without side effects and very versatile. Additionally, TMS is being tested in other settings, such as to combat the effects of post-stroke aphasia and cognitive decline.
It is not miraculous or curative, but it is a good option to combat the problems that will be more and more present with the aging of the population, such as degenerative disorders and communication difficulties.
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