Caution is still in order. But, if the trial is transformed, it could change the lives of many families. A team of researchers from Inserm, CNRS, Inrae and the University of Tours has just published promising results on a drug that would be effective in improving the interactions of patients with autism. We speak today of autism spectrum disorders (ASD), since this disease that affects neurodevelopment is heterogeneous. These TSAs would affect some 700,000 people in France, two-thirds of whom are adults. However, there is currently no medicine to help these patients. 20 minutes explains why this post has something to make you optimistic (but cautious).
What treatment is it?
The research team published an article in April 2022 in the scientific journal Neuropsychopharmacology revealing that bromide ions represent an interesting therapeutic pathway to alleviate autism symptoms. Knowing that potassium (belonging to bromide ions) is already used for epilepsy in veterinarians. “We tested the effect of bromide ions on mice,” explains Julie Le Merrer, co-author of the study. In autism, there is a change in the balance between excitation and inhibition in the brain. We tested this molecule, which inhibits the brain, in three models of autistic pathology with different mechanisms. We then carried out the most accurate behavioral analysis possible on these mice. And we notice on the one hand, a restoration of the durations of the nose contact. On the other hand, a reduction in the stereotyped behavior of the animals: the mice made fewer circles on themselves. The treatment also reduced the anxiety state of the mice.
In summary, this treatment allowed the animal a significant improvement of three symbolic symptoms of ASD: interaction difficulty, repetitive movements (stereotypy) and anxiety. And this in the three types of ASD and in the long term.
What are the limitations of the study?
We are talking about preclinical studies at the moment, so only in animals. Now it remains to be seen whether human patients react in the same way as mice. “We are reaching the great challenge, admits Julie Le Merrer. So far, autism research hasn’t been very successful, so these early results are no guarantee of success. »
In fact, one study looked at the effect of balovaptan on the socialization and communication skills of adults with ASD, but the treatment was not effective. Another experimented with oxytocin intranasally, without success. Third failure, this time with bumetanide. “There have been many disappointments in the last two years, sums up Frédérique Bonnet-Brilhault, head of the psychiatry department at the University Hospital of Tours and head of the Center of Excellence for Autism. This discourages labs from investing in autism research when there is a real need. »
Second limit: Bromide ions should be used with caution. “There is no addictive effect, instead from certain doses there is a sedative effect, a vigilance disorder, skin rashes, Julie Le Merrer enumerates. As soon as we see the first signs appear, we stop and they disappear. The problem is that with this drug the margin between the effective dose and the toxic dose is small. »
This means that this treatment requires close monitoring, with regular blood tests. “Which not all ASD patients are willing to accept,” she admits. But we looked for a solution that could be to combine the bromide ions with a molecule that would facilitate the activity of the mGlu4 glutamate receptor. This would improve efficiency, giving five times less dose of each molecule, thus limiting adverse effects and reducing monitoring limitations. »
Which are the next steps ?
“We will have to set up a clinical trial in adult patients”, stresses Julie Le Merrer. But the team of researchers is not ready yet and does not yet have a date for the start of this trial.
This clinical trial, if conclusive, would make it possible to define the dose to be prescribed and the way of administering it.. At the moment, what is planned is an oral treatment, with drops. So easy to take. “In children under 6 years of age, it cannot be tablets, but drops,” adds Frédérique Bonnet-Brilhault. In a second step, the researchers could also test the combination of the two molecules.
Why does this result give hope?
“Autism is the only field of medicine where therapy deals with the rehabilitation of language and motor skills, but we lack a therapeutic arsenal”, recalls Frédérique Bonnet-Brilhault. The interest with this molecule is that we have a significant effect on the social aspect, an area in which we are very poor, especially since interventions must start early and are strong. »
If this therapeutic approach is confirmed, “this pharmacological treatment will not replace the behavioral approaches used today, but will complement them, insists Jérôme Becker, a researcher at the University of Tours. We are not going to cure the disease but to make life easier for patients, especially adults” for whom early support is rarer. “First we will focus on children and adults who have a significant disability,” explains the head of the department of child psychiatry.
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