Hongmei Wu of the department of geriatrics at the West China Hospital of Sichuan University in Chengdu, China, led a systematic review of six trials involving a total of 454 patients.

The review, published in the Cochrane Library, suggests some cognitive and functional improvement as well as some reduction in behavioral disturbances in Alzheimer's patients taking Huperzin A when compared to Alzheimer's patients taking placebos.

"These findings are based on small number of trials, but the data indicate that it would be well worth setting up some more high quality assessments of this interesting drug," the study author says in a statement.

The researcher says Huperzine A inhibits cholinesterase which may help maintain the neurotransmitter acetylcholine and increase the ability of remaining cholinergic neurons. Part of the damage in Alzheimer's disease may be due a loss of brain neurons containing acetylcholine.

Cholinesterase is an enzyme that catalyzes a reaction breaking down acetylcholine that allows an activated cholinergic neuron to return to its resting state.