In a study that appears in the journal Science Translational Medicine, U.S researchers say that they have discovered a new drug that might reverse learning problems associated with Down’s syndrome.
In a study that was conducted by a team of scientists at Stanford University School of Medicine and the Lucile Packard Children’s Hospital in California, a precursor of a chemical ‘nor-epinephrine’ was used to reverse learning deficits in mice with symptoms very close to those seen in humans with Down’s syndrome.
Down’s syndrome is a condition wherein children have an extra copy of the 21st chromosome, which means there are an extra 300 or so genes and those genes play many different roles around the body. It is these genes that lead to a problem with contextual learning and some memory defects.
The mice used in the study had three copies of mouse chromosome 16, while in humans; it’s the case with chromosome 21. Both mice and children with this extra chromosome, suffer from contextual learning and memory deficits.
According to Ahmad Salehi, the lead researcher of the team, the brain function of a Down’s syndrome patient is, at some point, similar to that of a normal human being. This is the window of opportunity that needs to be spotted and used for treatment. He believes that with an early intervention, further deterioration of the cognitive dysfunction can be prevented, if not entirely reversed.
The current study tests mice to examine how the brain functions in Down’s syndrome and reveals that the ability to process information doesn’t fail in every aspect. Although Down Syndrome kids are not developmentally delayed at birth, as they age they struggle to use spatial and contextual information to form new memories, a function that depends on the hippocampus part of the brain. The hippocampus region of the brain receives nor-epinephrine from another part of the brain, locus coeruleus, in a process to form contextual memories.
But in the study of the mice with the Down’s syndrome-like condition, researchers noted that the locus coeruleus began to degenerate early on in the mice’s lives and hence such mice failed at simple cognitive tests that required them to be aware of changes in their environment. Administering doses of nor-epinephrine to such mice showed an improvement in their cognitive skills.
“This study explains why contextual learning is compromised in Down’s syndrome and suggests a new therapeutic strategy, because so far we have been targeting other systems for treating people with Down’s syndrome. There’s always hope that once we prove that this system, this strategy works then there is a hope that one day we could try to restore nor-epinephrinergic system in humans,” said Salehi.
The nor-epinephrine precursor used in the Down’s syndrome study is currently in clinical trials to treat fibromyalgia in humans, a chronic condition characterized by fatigue and widespread pain. Research is still underway and more work needs to be accomplished before starting human clinical trials.
Article by Snigdha Taduri for Biomed-ME