Researchers who experimented with a drug used previously in the treatment of epilepsy are planning to extend the study from lab rats to human subjects.
The researchers found that the drug called pentylenetetrazole, or PTZ, when administered daily to the rats which were bred to have genetic similarities to Down's Syndrome patients, elicited marked improvement in learning abilities.
Down's syndrome is the most frequent genetic cause of mental retardation and occurs equally around the world, in about one in every 800 births. About 5,000 children born in the United States each year have Down syndrome.
It is caused by the presence of a third chromosome, known as chromosome 21. Most people have two copies of each chromosome and the additional activity of the genes on the third copy of chromosome 21 is believed to cause the symptoms of Down syndrome.
The researchers were led by Craig Garner, a professor of psychiatry and a director of the Down Syndrome Research Center at California's Stanford University and they published results in the journal Nature Neuroscience.
Fabian Fernandez, a student in Garner's lab, was exploring the possibility that the brains of Down's patients are too strongly affected by a chemical called GABA, a neurotransmitter, or message-carrying chemical. This stops brain cells from becoming too excited.
In general, learning involves neuronal excitation in certain parts of the brain.
Says Garner "For example, caffeine, which is a stimulant, can make us more attentive and aware, and enhance learning."
PTZ does this by causing more GABA to be available in the brain. Overdoing this process can cause seizures. PTZ was once used to study epilepsy but it is no longer approved for use in people.
Fernandez gave daily doses of PTZ to the mice for about 2 weeks.
The mice were better able to navigate mazes and recognize new objects after receiving the drug, and were on par with normal mice.
The gains continued for months after the treatment stopped. This makes the scientists believe that as it can cause long-term changes in the brain, it can probably be used as a psychotherapy drug.
Concludes Garner: We think we're slowly being able to understand what's causing reduced cognitive ability in people with Down syndrome and there are new approaches and strategies that could improve their quality of life.