Scientists have found that in Down syndrome there is a reduced level of the pleiotrophin molecule, which is important for the development and functioning of the nervous system.[1][2] This molecule is found in high levels during key stages of brain development and helps form synapses, the connections between nerve cells, as well as axons and dendrites.[1][3] In experiments on mice with a model of Down's syndrome, they administered pleiotrophin to astrocytes, specialized brain cells.[1][4] This led to an increase in the number of synapses in the hippocampus and improved brain plasticity, the ability to create or change connections for learning and memory.[3][5] The study serves as a proof-of-concept that targeting astrocytes can rewrite brain circuits in adults as well.[1][2] The research was led by Nicola J. Allen of the Salk Institute and involved Ashley N. Brandebura of the University of Virginia.[1][4] Pleiotrophin is not the only factor involved in disorders in Down syndrome, but the approach may help in other neurological diseases as well.[3][5]