Asthma drug could restore cognitive decline in Down syndrome
Researchers at Stanford University School of Medicine found that in mice, the asthma medication formoterol, already available on the market, strengthened nerve connections in the hippocampus--the part of the brain responsible for spatial navigation, attention span and forming new memories--and improved contextual learning.
Down syndrome occurs in the presence of an extra copy of chromosome 21, and the disease causes physical and cognitive problems, including impaired hippocampal function and contextual learning. Both of these cognitive functions require a healthy supply of the neurotransmitter norepinephrine in the brain, which sends its signal via several types of receptors on the neurons, including a group called beta-2 adrenergic receptors. Previous research has shown that in both people with Down syndrome and its animal model, deterioration occurs in the brain center that manufactures norepinephrine.
The Stanford scientists homed in on the beta-2 adrenergic receptors, giving mice a compound that blocks the action of beta-2 adrenergic receptors outside the brain then administering formoterol, which can partially cross the blood-brain barrier and is known to activate beta-2 adrenergic receptors.
In addition to improvements on contextual learning tests, the researchers also observed more synapses and a more complex structure of dendrites--the nerves' outgoing ends--in the hippocampus after mice were given formoterol. The study results will appear online July 2 in the journal Biological Psychiatry.
While most physical manifestations of Down syndrome can now be treated, no therapies exist to improve cognitive function in patients.
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