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Dublin: 8°C Tuesday 15 June 2021

Scientists reverse Down syndrome-like learning deficits in mice

Scientists in the US injected a compound into the mice which enabled part of their brains to grow to normal size.

Image: Mouse in lab via Shutterstock

RESEARCHERS AT JOHNS Hopkins in the US have identified a compound that dramatically bolsters learning and memory when injected into mice with a Down syndrome-like condition on the day of birth.

The single-dose treatment appears to enable the cerebellum of the rodents’ brains to grow to normal size.

While this is a big step in the research, the scientists have cautioned that the use of the compound has not been proven safe to try in people with Down syndrome.

“Most people with Down syndrome have a cerebellum that’s about 60 per cent of the normal size,” said Roger Reeves, a professor at the Johns Hopkins University School of Medicine.

We treated the Down syndrome-like mice with a compound we thought might normalise the cerebellum’s growth, and it worked beautifully. What we didn’t expect were the effects on learning and memory, which are generally controlled by the hippocampus, not the cerebellum.

The mice used in the experiment were genetically engineered to have extra copies of about half of the genes found on human chomosome 21. Researchers said the mice have many characteristics similar to those of people with Down syndrome, including relatively small cerebellums and difficulty learning and remembering how to navigate through a familiar space.

A compund was injected into the mice just once on their day of birth while their cerebellums were still developing and Reeves said researchers were able to “completely normalise” its growth through adulthood with that single injection.

The team noticed a change in behaviour of the mice as well as this, recording that treated mice did as well as normal ones in a water maze test.

Reeves said further tests are needed to establish why the treatment works and though it has the potential to become a human drug, there are risks such as raising the risk of cancer by triggering inappropriate growth.

Read: New bill would recognise Down syndrome as ‘low incidence’ disorder>
Read: Boy, 15, becomes first teen with Down syndrome to reach Everest base>

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