Researchers at California's Stanford University report a drug known as PTZ can improve the learning and memory of lab mice with Down syndrome.

After receiving once-daily doses of PTZ, or pentylenetetrazole, researchers found the Down syndrome mice could recognize objects and navigate mazes as well as normal mice, The Los Angeles Times reported.

The improvements lasted up to two months after the drug was discontinued according to a report by the researchers in the journal Nature Neuroscience.

Lead author Craig C. Garner, a professor at the Stanford School of Medicine, told the Times that after more preliminary studies his lab will prepare for conducting human trials.

Down syndrome is the leading cause of mental retardation. It results from an extra copy of chromosome 21.

Copyright 2007 by United Press International