Huperzine A is an extract from a club moss (Huperzia serrata) that has been
used for centuries in Chinese folk medicine. Its action has been attributed
to its ability to strongly inhibit acetylcholinesterase, the enzyme that
breaks down acetylcholine in the synaptic cleft (see chapter 4).
Acetylcholine is involved in memory and learning. By inhibiting the enzyme
that breaks it down, more acetylcholine becomes available to stimulate
neurons. Alzheimer's disease is a condition where there's a relative shortage
Several studies have been done over the past few years with huperzine A both
in China and the United States. These studies have shown that Huperzine A is
many times more effective and selective than tacrine (a
cholinesterase-inhibiting pharmaceutical drug) in inhibiting cholinesterase
(Cheng 1996). Huperzine A has also been found to be beneficial in patients
with Alzheimer's disease. Scientists at Zhejiang Medical University, in
Hangzhou, China administered 0.2 mg of huperzine A to fifty patients with
Alzheimer's disease for a period of eight weeks and compared the results to a
group who received placebo pills (Xu 1995). The study was done in a double
blind, placebo controlled and randomized manner. The results showed 58
percent of the patients treated with huperzine A had improvements in memory,
cognition, and behavioral functions whereas only 36 percent of those on
placebo improved. No severe side effects were found. Blood pressure, heart
rate, electrocardiogram, electroencephalogram, liver and urine tests did not
show any major abnormalities. The researchers say, "Huperzine A is a
promising drug for symptomatic treatment of Alzheimer's disease."
This club moss extract may also benefit older individuals with dementia. A
study was conducted with fifty-six patients suffering from multi-infarct
dementia (multiple small strokes) and one hundred patients with senile memory
disorders (Zhang 1991). The dose used for multi-infarct dementia was 0.05 mg
twice a day for four weeks, whereas that for senile memory disorders was 0.03
mg twice a day for two weeks. Most patients had an improvement in memory. A
few reported slight dizziness, but this did not affect the therapeutic
Huperzine was even mentioned in the Journal of the American Medical
Association as a possible herbal therapy for Alzheimer's disease (Skolnick
Huperzine A is sold either by itself in dosages of 0.05 mg, or in lower
dosages combined with other mind-boosting nutrients.
My Personal Experience
I took a capsule containing 50 micrograms (0.05 mg) of huperzine A in the
morning at 9 AM on an empty stomach. Within an hour I could feel a subtle
effect. This consisted mostly of feeling slightly more alert and focused.
Over the next hour I took two additional capsules and then ate breakfast. My
focus and concentration were slightly improved all day long and well into the
evening. It didn't seem that huperzine A had any effect on mood, libido, or
appetite. No side effects occurred.
One study has shown that huperzine A is absorbed rapidly when taken orally,
distributed widely in the body, and eliminated at a moderate rate (Qian
1995). This rapid absorption and moderate elimination is consistent with my
observation of the effects within an hour and the continuation of the effects
late into the evening.
Huperzine A appears to be a promising alternative to cholinesterase inhibitor
drugs used in Alzheimer's disease. More studies are required to determine its
long-term safety and side effect profile. Until we learn more about this
herbal extract, I would recommend its use be limited to the therapy of AD,
and preferably under medical supervision.