Findings from the Stanford University School of Medicine and Lucile Packard Children’s Hospital shed light on the neural basis of memory defects in Down syndrome and suggest a new strategy for treating the defects with medication.
At birth, children with Down syndrome aren’t developmentally delayed. But as they age, these kids fall behind. Memory deficits inherent in Down syndrome hinder learning, making it hard for the brain to collect experiences needed for normal cognitive development.
The study, which was conducted in mice, is the first to show that boosting norepinephrine signaling in the brains of mice genetically engineered to mimic Down syndrome improves their cognition. Norepinephrine is a neurotransmitter that nerve cells use to communicate.
“If you intervene early enough, you will be able to help kids with Down syndrome to collect and modulate information,” said Ahmad Salehi, MD, PhD, the primary author of the study, which is published in Science Translational Medicine.
“Theoretically, that could lead to an improvement in cognitive functions in these kids.” Salehi, a research health science specialist at the Veterans Affairs Palo Alto Health Care System, was a senior scientist at the School of Medicine when the study was conducted.
Down syndrome is a genetic disorder caused by an extra copy of chromosome 21. Using a mouse model, Salehi and his colleagues are examining exactly how the brain malfunctions in Down syndrome. “Cognition doesn’t fail in every aspect; it’s failing in a structure-dependent fashion,” he said.
The study revealed two important new findings about Down’s syndrome in a mouse model:
1) there is evidence that synaptic terminals involved in neurotransmission are damaged long before the cells show degeneration; and
2) while cell signaling is damaged, the receptors are not, but are functioning and still trying to find signals.
Salehi’s results give “a ray of hope and optimism for the Down syndrome community for the future,” said Melanie Manning, MD, director of the Center for Down Syndrome at Lucile Packard Children’s Hospital. Manning was not a part of Salehi’s research team. “It’s very exciting,” she said. “We still have a long way to go, but these are very interesting results.”
Source: Stanford University Medical Center, USA