A new hormone treatment improved the cognitive function of six men with Down syndrome by 10% to 30%, scientists said this week, adding that the ‘promising’ results could offer hope for improved quality of life for patients .
However, the scientists stressed that the small study did not point to a cure for cognitive impairment in people with Down syndrome and that much more research was needed.
“The experience is very satisfying, even if we remain cautious,” says Nelly Pitteloud of Lausanne University Hospital in Switzerland, co-author of a new study in the journal Science, said Thursday.
Down syndrome is the most common genetic form of intellectual disability, occurring in about one in 1,000 people, according to the World Health Organization.
Yet previous research has failed to significantly improve cognition when applied to people with the condition, which is why the latest findings are “particularly important”, according to the study.
Recent findings have suggested that the way gonadotropin-releasing hormone (GnRH) is produced in the brain may affect cognitive functioning such as memory, language, and learning.
GnRH hormones regulate the amount of testosterone and estrogen produced, and increased levels of these help stimulate puberty.
“We wondered if this hormone could play a role in establishing the symptoms of people with Down syndrome,” said Vincent Prevot, co-author of the study and head of neuroscience research at INSERM. in France.
The team first established that five strands of microRNAs regulating GnRH production were dysfunctional in mice specifically designed for Down syndrome research.
They then demonstrated that cognitive impairments – as well as loss of smell, a common symptom of Down syndrome – were linked to malfunctioning GnRH secretion in mice.
The team then gave the mice a GnRH drug used to treat low testosterone and delayed puberty in men, finding that it restored certain cognitive functions and the sense of smell.
A pilot study was conducted in Switzerland among seven men with Down syndrome aged 20 to 50 years.
They each received the treatment through the arm every two hours over a six-month period, with the drug given in pulses to mimic the frequency of the hormone in people without Down syndrome.
Cognitive and olfactory tests were performed during treatment, as well as MRIs.
Six of the seven men showed improvement in cognition with no significant side effects, and none showed a change in smell.
“We saw a 10-30% improvement in cognitive functions, particularly with visuospatial function, three-dimensional representation, understanding of instructions as well as attention,” Pitteloud said.
Patients were asked to draw a simple 3D bed at several stages of therapy. Many struggled at first, but in the end the efforts were much better.
“Improving the quality of life”
The authors acknowledged some limitations of the study, including its size and the fact that patients’ choice was “parent-driven”.
“The clinical trial only focused on seven male patients – we still have a lot of work to do to prove the efficacy of GnRH treatment for Down syndrome,” Pitteloud said.
A larger study involving a placebo and 50 to 60 patients, a third of them women, should begin in the coming months.
“We are not going to cure the cognitive impairments of people with Down syndrome, but the improvement seen in our results already seems fundamental enough to hopefully improve their quality of life,” said Pitteloud.
Fabian Fernandez, a cognition and Down syndrome expert at the University of Arizona who was not involved in the research, praised the study’s “tour de force”.
He told AFP that while it is “difficult to imagine” how such an intensive treatment could be used for young people, it might be better suited to delay the Alzheimer’s-related dementia suffered by many. adults with Down syndrome.
It was also difficult to predict how such an improvement might impact the lives of people with the disease, he said.
“For some it might be important, however, as it would allow them to be more independent in activities of daily living such as looking after and enjoying hobbies, finding belongings, using household appliances home and travel alone.”