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A hormone could help in the repair of cognitive functions
SCIENCE - Hope for people with Trisomy 21 ? A therapy tested on seven patients improved some of their cognitive functions. Judged results "promising" which have yet to be confirmed. "The experience is very satisfying, even if we remain cautious"summarized Nelly Pitteloud, head of the endocrinology department at the Vaud University Hospital Center (CHUV), presenting to the press the study published Thursday, September 1 in the journal Science.
His hospital collaborated with a team from Inserm - within the Lille laboratory neurosciences and cognition — to test the effectiveness of a therapy based on the injection of l’hormone GnRH (Gonadotropin-Releasing Hormone) at patients carriers of trisomy 21.
"We wondered if this hormone could play a role in the establishment of the symptoms present in carriers of trisomy 21", explained Vincent Prévot, research director at Inserm. Recent discoveries have suggested that neurons expressing the GnRH hormone, known to regulate reproduction via the hypothalamus, may also have an effect on cognitive functions (memory, language, reasoning, learning, problem solving, etc.).
First on mice, the laboratory established that five micro-RNA strands regulating the production of this hormone and present on chromosome 21 were deregulated. The scientists succeeded in demonstrating that the progressive cognitive and olfactory deficiencies of these mice were closely linked to dysfunctional GnRH secretion.
Satisfactory human tests
They then proved that the reactivation of a normal GnRH system made it possible to restore cognitive and olfactory functions in mice with Down syndrome. Nelly Pitteloud's team then took over. A pilot clinical trial was conducted on seven men with Down syndrome, aged 20 to 50, between October 2020 and May 2022. Patients received a dose of GnRH every two hours subcutaneously for 6 months, via a pump on the arm.
Cognition and smell tests as well as MRI examinations were carried out before and after the treatment. "There was an improvement of between 10% and 30% in cognitive functions, in particular visuo-spatial function, three-dimensional representation, understanding of instructions and attention"and égrené Nelly Pitteloud.
Thus, a patient who struggled to reproduce the diagram of a 3D cube before the start of treatment, managed to draw a bed correctly at the end. Clinically, cognitive performance increased in 6 out of 7 patients, improvements confirmed by brain imaging.
The results of the study are also welcomed by independent experts. Calling her a "tour de force"Fabian Fernandez, specialist in cognition and trisomy 21 at the University of Arizona (United States), judged his results “irreproachable. »
A larger study in the fall
However, unlike what happened with the mouse, the treatment had no impact on olfaction. These results "promising" must be confirmed. “Clinical work focused on only 7 male patients; to prove the effectiveness of GnRH treatment in trisomy 21, we still have a lot of work to do”recognized Nelly Pitteloud.
The authors of the study recognize other biases, such as the presence of patients who are already very stimulated by their parents. They would now like to include people with more varied profiles, including some with degenerative signs such as Alzheimer's.
In the fall, a larger study involving 50 to 60 people and a placebo should be launched. The researchers hope to include " a third " women, who must not be on contraception - the GnRH hormone regulating reproduction - nor wish to become pregnant.
“We are not going to cure the cognitive disorders of people with Down syndrome, but in our results, the improvement already seems quite essential to hope to increase their quality of life”rejoiced Nelly Pitteloud.
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