May 8, 2008 (Washington) -- A form of Asian ginseng shows promise for relieving schizophrenia symptoms that are difficult to treat.
In a small study, patients had fewer negative symptoms -- such as lack of motivation and a severe reduction in emotional expression known as "flat affect" -- when they took Panax ginseng than when they took a placebo.
Schizophrenia afflicts 3.2 million Americans. Though there is no cure, antipsychotic medications are very effective at reducing what doctors call the "positive" symptoms of schizophrenia -- hallucinations, delusions, and disordered thinking.
But "what causes the most impairment are 'negative' symptoms and cognitive impairment," says National Institute of Mental Health Director Thomas Insel, MD. They include flat affect, lack of pleasure or motivation in everyday life, and an inability to converse meaningfully, even when forced to interact.
Animal and lab studies suggest that Panax ginseng hits some of the same targets in the brain as drugs being developed to treat both negative and positive symptoms of schizophrenia, according to Canadian researchers.
They studied Panax ginseng in 42 schizophrenia patients who continued to suffer negative symptoms despite treatment with antipsychotic medications.
Ginseng and Schizophrenia Symptoms
The patients were given one of two doses of Panax ginseng or a placebo for eight weeks. Then, patients taking ginseng were switched to placebo and patients on placebo were given ginseng for another eight weeks.
Patients continued to take their standard antipsychotic drugs throughout the study.
Results showed that patients were 50% less likely to have flat affect when taking the higher, 200-milligram dose of ginseng than when taking placebo.
The higher dose also significantly reduced other negative symptoms, says Simon S. Chiu, MD, PhD, associate professor of psychiatry at the University of Western Ontario.
"Unexpectedly, ginseng's effect on reducing symptoms continued even when the patients were crossed over to placebo," he tells WebMD.
Side effects, including dry mouth and constipation, were no more likely with ginseng treatment than placebo.
The results were presented at the annual meeting of the American Psychiatric Association.
Chiu says that "it's too soon to tell people to take ginseng for schizophrenia. But it shows promise as an adjunct to their other antipsychotic medications."
A larger, longer study pitting Asian ginseng against placebo in schizophrenia patients whose negative symptoms persist on antipsychotic medication is merited, he adds.
David Baron, DO, chairman of the committee that chose which studies to highlight at the meeting, tells WebMD that some studies of complementary and alternative medical remedies are "lacking in science. But this is potentially promising."
"There's a signal here; the fact that Panax ginseng works on the same brain receptors [as antipsychotic drugs] makes it something to look at," says Baron, professor and chairman of the department of psychiatry at Temple University in Philadelphia.