2006-02-03
Monika Guttman

A clinical trial to test the Chinese herb Huperzia serrata—known commercially as huperzine A—as a treatment for early or mild Alzheimer’s disease is underway at USC, announced Lon Schneider, professor of psychiatry, neurology and gerontology at the Keck School of Medicine of USC.

Schneider, who is spearheading USC’s participation in the multi-center Phase II trial sponsored by the National Institute on Aging, noted that earlier trials suggested huperzine A works much like some of the main medications now prescribed to treat Alzheimer’s symptoms. “Aricept, Razadyne, Exelon—the current drugs used to ease Alzheimer’s symptoms—are expensive and have side effects,” he said. “What’s potentially attractive about huperzine is that it’s an herb that’s been chewed by people over the course of centuries because of its cholinergic effects. It’s very available and easy to extract from the plant, may have fewer side effects and would cost much less than the current drugs for Alzheimer’s disease.”

Current medications like Aricept inhibit acetylcholinesterase, an enzyme that deactivates the neurotransmitter acetylcholine. Acetylcholine is involved in memory and learning. By inhibiting the enzyme that breaks it down, more acetylcholine continues to be available to stimulate neurons. Medications that block acetylcholinesterase may improve symptoms in some patients but do not stop the progression of Alzheimer’s.

Huperzine A, a naturally occurring compound found in a moss from the tropical woodland regions of China, has long been used by traditional healers as a fever and inflammation remedy. The compound is extracted from a Chinese herbal plant named Huperzia serrata, Shuangyiping, or Qian Ceng Ta. Huperzine A has become the most commonly prescribed medication in China for Alzheimer’s disease and other memory disorders, and appears to be able to improve memory loss and possibly slow the emergence of some symptoms of Alzheimer’s, especially in the early stages.

Delaying onset of some symptoms may delay the onset of disability. Finding a treatment that could delay onset by even five years could reduce the number of individuals with Alzheimer’s disease by nearly 50 percent after 50 years, according to the Alzheimer’s Association. Currently 4.5 million Americans have Alzheimer’s, more than double the number in 1980.

The huperzine A study, said Schneider, is intended to show whether the herb improves cognitive function in those already diagnosed with Alzheimer’s. It will also show what dosage may be most effective, and whether there are significant adverse effects. “Most of the information we have so far is anecdotal—there just hasn’t been well-designed clinical trials of this herb,” he noted.

Yet huperzine A, which is available commercially in health food stores and on web sites, is already being used by some doctors and patients to treat Alzheimer’s. The danger with that approach, said Schneider, is that huperzine is not regulated by the Food and Drug Administration with regard to purity and amount of substance because it is an herb. “With most substances regulated as nutraceuticals or diet supplements you never know what you’re getting.

It can be a broad range of substances of differing quality. The trial huperzine A is derived through a pharmaceutical-grade extraction process so it’s more than ninety-nine and forty-four hundredths percent pure, and so we know what dosages we’re giving.”

That is important, he noted, because it is possible to overdose on drugs that block acetylcholinesterase. “If someone added huperzine to Aricept, for example, they risk nausea, vomiting, confusion, muscle cramping, respiratory difficulties and even seizures,” he said.

What makes huperzine more attractive than the current pharmacologic treatments is that “it may be a bit different, it may have certain benefits the current treatments do not,” said Schneider. Yet, he cautioned, “We don’t have unrealistic expectations. This cholinesterase inhibitor may have a more favorable side effect profile, so it may make a difference. We have expectations that it will help, but this is still in the very early stages.”

The huperzine A trial is currently seeking participants who have not found current medications effective or tolerable, are 55 years and older with Alzheimer’s disease and are not taking other cholinesterase inhibitors. For more information please call Shirley Sian or Morella Menicucci at (323) 442-7600 or e-mail gsc@usc.edu.

Additional information on this trial and on Alzheimer’s disease in general can be found on the USC Geriatric Studies Center Alzheimer’s Disease Research Center website at http://www.usc.edu/memory.