Huperzine A in Alzheimer's Disease

Huperzine A is a natural cholinesterase inhibitor derived from the Chinese herb Huperzia serrata. There is evidence that huperzine A may compare favorably in symptomatic efficacy to cholinesterase inhibitors currently in use. In addition, huperzine A has antioxidant and neuroprotective properties that suggest that it may be useful as a disease-modifying treatment for Alzheimer's disease (AD). The drug is currently available as a nutraceutical in this country, and is being used by some U.S. clinicians to treat AD. However, there have been no controlled clinical trials outside China assessing its toxicity and efficacy. The present study will evaluate huperzine A in the treatment of AD in a randomized controlled trial of its effect on cognitive function. The primary aim of this multicenter, double-blind, placebo-controlled therapeutic Phase II trial is to determine whether treatment with huperzine A 200µg twice a day improves cognitive function in individuals with AD. Secondary aims of this study are to: a) determine whether treatment with huperzine A 400µg twice a day improves cognitive function in individuals with AD; b) determine the effect of huperzine A treatment on global clinical status, activities of daily living, and behavior in AD; c) evaluate the tolerability of huperzine A treatment at dosages of 200µg twice a day and 400µg twice a day in AD; and d) determine the relationship between blood cholinesterase activity and cognitive function in individuals with AD treated with huperzine A. A total of 150 participants will be randomly assigned to three groups of equal size. This will allow a comparison of huperzine A 200µg twice a day, huperzine A 400µg twice a day, and placebo. The primary outcome measures will be the change in score on the ADAScog at the 16 week visit. Secondary outcome measures include the ADCS clinical global impression of change (CGIC) (Schneider et al 1997) and activities of daily living (ADL) (Galasko et al 1997) scales, and the Neuropsychiatric Inventory (Cummings 1997). Volunteers must be able to participate in the study for 24 weeks and make 9 visits to the trial site. At the end of the double-blind study, participants will be invited to continue huperzine A treatment for 6 months in an open-label extension phase. Participants will receive 200µg of huperzine A twice a day for six consecutive months, and will be assessed at 3-month intervals (months 6, 9, and 12, with month 6 assessments coinciding with the final visit of the double-blind phase).