Ayurvedic Medicine for Schizophrenia--Mental Health Researchers Explore Hindu Herbs
by Scott J Brown published in Clinical Psychiatry News December, 1995, p. 15
Washington--Mainstream scientists are beginning to get interested in the use of herbal medicines for psychiatric disorders, Jerry Cott, PhD said at a conference on medicinal and natural products.
Much of the interest has been sparked by research done through the natural products screening program of the National Institute of Mental Health, which has been examining the receptor-binding capabilities of medicinal plants.
The screening program has so far tested 146 natural products and found that many of them are in fact pharmacologically active, said Dr. Cott, chief of the pharmacologic treatment research program, NIMH, Rockville, Md.
Most of the products tested are herbal remedies from the traditional Hindu system of medicine known as Ayurveda. Researchers in India had tested the efficacy of a particular Ayurvedic herbal mixture in the treatment of schizophrenia, comparing it to the antipsychotic chlorpromazine in a placebo-controlled trial. The Ayurvedic compound worked almost as well as chlorpromazine, with many "fewer side effects," he said at the conference, sponsored by International Business Communications, Southborough, Mass.
One of the components of this medicine is the plant Rauwolfia serpentina [ sarpagandha], from which reserpine, a drug known to have antipsychotic effects, is derived. An analysis of the receptor-binding affinities of a crude extract of Rauwolfia revealed that this plant also contains other psychotropic compounds. It was found, for instance, to contain an unidentified compound with fairly high binding affinity for dopamine2 receptors.
The Rauwolfia was also found to have binding affinity for alpha2-adrenergic receptors. This is important, Dr. Cott said, because preliminary research shows that adding an alpha2 antagonist to an antipsychotic will enhance the action of the antipsychotic without increasing the side effects, Dr. Cott said. One problem with using reserpine as a medicine is that it has nasty side effects. But when Rauwolfia is used in its crude form, the compound that is binding to the alpha2 receptors may act to cut the side effects of the reserpine in the plant.
Another plant known to have psychotropic effects is Saint-john's wort (Hypericum perforatum), which has antidepressant activity. One of the active compounds of this plant is hypericin, which has been thought to be an MAO inhibitor. Analysis of hypericin revealed, however, that it did not inhibit MAO, but a crude extract of Saint-john's wort did inhibit MAO.
The crude extract was found to have high binding affinity for gamma-aminobutyric acid type A and B receptors. Saint-john's wort may be exerting some of its psychotropic effects through these receptors, he said.
The World Health Organization is planning to do a multinational study of the use of ginkgo in treating Alzheimer's disease. Ginkgo has antioxidant activity and neuroprotective activity, Dr. Cott said. It could be useful as an adjunct in treating disorder like schizophrenia where neuronal degeneration occurs as a side effect with antipsychotic drugs.
A researcher at Boston University is planning to conduct a study to see whether ginkgo can enhance cognition in patients with schizophrenia, he said. The World Health Organization has recently completed a study of the use of ginkgo as an adjunct to the tricyclic amitriptyline in the treatment of depression.