Drugs boosting levels in the brain of the neurotransmitter norepinephrine may be able to help counter the memory deficits that hinder the cognitive development in people with Down syndrome, according to a new animal study published in Science Translational Medicine. Hindered memory-making robs the brain’s ability to collect the experiences needed for normal cognitive development, say the Stanford University School of Medicine and Lucile Packard Children’s Hospital researchers behind the study.

 

Ahmad Salehi, the study’s primary author, says that if a similar intervention is applied early enough to Down syndrome children, it could help them collect and modulate information.

 

Elevating the norepinephrine signaling in the brains of genetically engineered Down syndrome mice can help rapidly restore cognitive function, helping them tackle simple cognitive challenges, according to the paper. After the treatment, affected mice that failed to build nests in new environments were able to make nests as well as normal mice, the researchers found.

 

Some drugs already on the market for depression and attention deficit hyperactivity disorder target the norepinephrine system, Salehi says. He hopes the new results will spur tests of those drugs for Down syndrome.

 

The benefits of promoting norepinephrine production in mice accrue because the Down syndrome’s cognitive impairment is structure-dependent, the researchers found. Like humans with Down syndrome, the model mice exhibited early degeneration of the locus coeruleus, a part of the brain that supplies norepinephrine to the hippocampus, which is responsible for the formation of contextual or relational memories.

 

By supplying norepinephrine precursors to the mice with the Down syndrome-like condition, the researchers put their cognitive abilities on par with those of normal mice. The positive effects, which took just a few hours to display, also wore off relatively quickly, said Salehi.

 

Past studies of Down syndrome drug therapies have targeted acetylcholine, a different neurotransmitter that also acts on the hippocampus. Salehi said his team’s experiment show that the ideal medication regimen for improving cognition in Down syndrome will likely improve both norepinephrine and acetylcholine signals in the brain.