Huperzine A
Huperzine A is an alkaloid extracted from the firmoss plant (Huperzia Serrata). It has been used in china for centuries for treatment of numerous conditions. The summary of studies below shows that huperzine A is effective at improving memory and cognition however this has almost exclusively been demonstrated in brain functioning below optimal. In healthy brains it is still unclear if huperzine A has enhancing effects but the few studies involving healthy brains show no effect.
Most beneficial for - underperforming or older brains
Effective dose - 100-400mcg daily
Length of action - begins to act immediately
Safety - no serious side effects reported only some associated with cholinergic drugs (eg. insomnia)
Type of cognition effected - mainly memory
Enhancers - green tea (EGCG)
Supporting Studies
Efficacy of tablet huperzine-A on memory, cognition, and behavior in Alzheimer's disease (Xu et al, 1995)
A double blid placebo controlled trial where 50 Alzheimer's patients received 200mcg of huperzine A daily and 53 a placebo daily for 8 weeks. Half of the patients taking the huperzine A showed improvements in memory, cognition and behavioral functions compared to the placebo group. No serious side effects were observed.
Huperzine-A capsules enhance memory and learning performance in 34 pairs of matched adolescent students (Sun et al, 1999)
Sixty eight adolescent students received either 100mcg of huperzine A or a placebo daily for 4 weeks. At the end of the 4 weeks the huperzine A group scored on average 10% higher on memory tests than the placebo group. The scores of the Huperzine A group were also markedly higher than the placebo group in their chinese language classes.
Huperzine-A capsule in treatment of age-associated memory impairment with a double-blind study (Sheng et al, 2003)
A double blind study comparing Huperzine A tablets to capsules. Both groups received 300mcg daily of Huperzine A either in capsule or tablet form. Both groups consisted of about 60 people with age associated memory deficits. Both groups showed significant improvements in memory test scores indicating.
Effects of Chronic Administration of Huperzine A on Memory in Guinea Pigs (Filliat et al, 2002)
Huperzine A at 1 microgram per hour was administered to guinea pigs. This produced a memory enhancing effect was shown that was limited to the first day of administration. Lower doses showed no effects.
The effects of huperzine A and IDRA 21 on visual recognition memory in young macaques (Malkova et al, 2011)
Six healthy monkeys were trained in memory exercises. They were then given huperzine A and tested again. The addition of huperzine A did not result in improved memory over the normal test, however it did result in fewer poor results. This suggest that it does not improve performance in optimal brains but can aid when the brain is not at its best.
Improving effects of huperzine A on spatial working memory in aged monkeys and young adult monkeys with experimental cognitive impairment (Ye et al, 1999)
Monkeys were given the drug scopolamine to produce cognitive impairment. They then received Huperzine A. The Huperzine A significantly reversed the cognitive deficits caused by the scopolamine and continued to do so for over 24 hours. This suggest that Huperzine A is useful in improving problems associated with working memory.
Huperzine A ameliorates the spatial working memory impairments induced by AF64A (Zhi et al, 1995)
A compound AF64A was used to impair rat spatial working memory. Huperzine A administration at 0.4-0.5mg/kg was able to ameliorate the effects of the AF64A compound on spatial working memory. This effect is likely due to the huperzine A's enhancement of brain cholinergic function.
Effects of huperzine A on memory deficits and neurotrophic factors production after transient cerebral ischemia and reperfusion in mice (Wang et al, 2006)
Rats were inflicted with the equivalent of a stroke. They then received huperzine A 0.2mg/kg daily 2 days after the stroke and 5 more days thereafter. Huperzine A markedly reduced memory deficits and neuronal damage and increased levels of protection and repair molecules in the brain compared to control animals.
Safety
Clinical efficacy and safety of huperzine Alpha in treatment of mild to moderate Alzheimer disease, a placebo-controlled, double-blind, randomized trial (Zhang et al, 2002)
A double blind trial of 200 Alzheimer's patients. Half were given 400mcg daily of huperzine A and half a placebo for 12 weeks. Cognition, mood and behavior were significantly improved in those taking huperzine A. Mild adverse effect (insomnia and ankle edema) were observed in 3% of patients taking huperzine A.
Bioavailabilty
Green tea polyphenol (-)-epigallocatechin-3-gallate enhances the inhibitory effect of huperzine A on acetylcholinesterase by increasing the affinity with serum albumin (Zhang et al, 2009)
Huperzine A alone and Huperzine A with a green tea polyphenol EGCG (epigallocatechin-3-gallate) were administered to mice. The combined huperzine A/EGCG markedly enhance the inhibitory effect of huperzine A on acetylcholinesterase and increased its time of action. This means EGCG can be used to reduce the dosage required of huperzine A or increase its effects.
Most beneficial for - underperforming or older brains
Effective dose - 100-400mcg daily
Length of action - begins to act immediately
Safety - no serious side effects reported only some associated with cholinergic drugs (eg. insomnia)
Type of cognition effected - mainly memory
Enhancers - green tea (EGCG)
Supporting Studies
Efficacy of tablet huperzine-A on memory, cognition, and behavior in Alzheimer's disease (Xu et al, 1995)
A double blid placebo controlled trial where 50 Alzheimer's patients received 200mcg of huperzine A daily and 53 a placebo daily for 8 weeks. Half of the patients taking the huperzine A showed improvements in memory, cognition and behavioral functions compared to the placebo group. No serious side effects were observed.
Huperzine-A capsules enhance memory and learning performance in 34 pairs of matched adolescent students (Sun et al, 1999)
Sixty eight adolescent students received either 100mcg of huperzine A or a placebo daily for 4 weeks. At the end of the 4 weeks the huperzine A group scored on average 10% higher on memory tests than the placebo group. The scores of the Huperzine A group were also markedly higher than the placebo group in their chinese language classes.
Huperzine-A capsule in treatment of age-associated memory impairment with a double-blind study (Sheng et al, 2003)
A double blind study comparing Huperzine A tablets to capsules. Both groups received 300mcg daily of Huperzine A either in capsule or tablet form. Both groups consisted of about 60 people with age associated memory deficits. Both groups showed significant improvements in memory test scores indicating.
Effects of Chronic Administration of Huperzine A on Memory in Guinea Pigs (Filliat et al, 2002)
Huperzine A at 1 microgram per hour was administered to guinea pigs. This produced a memory enhancing effect was shown that was limited to the first day of administration. Lower doses showed no effects.
The effects of huperzine A and IDRA 21 on visual recognition memory in young macaques (Malkova et al, 2011)
Six healthy monkeys were trained in memory exercises. They were then given huperzine A and tested again. The addition of huperzine A did not result in improved memory over the normal test, however it did result in fewer poor results. This suggest that it does not improve performance in optimal brains but can aid when the brain is not at its best.
Improving effects of huperzine A on spatial working memory in aged monkeys and young adult monkeys with experimental cognitive impairment (Ye et al, 1999)
Monkeys were given the drug scopolamine to produce cognitive impairment. They then received Huperzine A. The Huperzine A significantly reversed the cognitive deficits caused by the scopolamine and continued to do so for over 24 hours. This suggest that Huperzine A is useful in improving problems associated with working memory.
Huperzine A ameliorates the spatial working memory impairments induced by AF64A (Zhi et al, 1995)
A compound AF64A was used to impair rat spatial working memory. Huperzine A administration at 0.4-0.5mg/kg was able to ameliorate the effects of the AF64A compound on spatial working memory. This effect is likely due to the huperzine A's enhancement of brain cholinergic function.
Effects of huperzine A on memory deficits and neurotrophic factors production after transient cerebral ischemia and reperfusion in mice (Wang et al, 2006)
Rats were inflicted with the equivalent of a stroke. They then received huperzine A 0.2mg/kg daily 2 days after the stroke and 5 more days thereafter. Huperzine A markedly reduced memory deficits and neuronal damage and increased levels of protection and repair molecules in the brain compared to control animals.
Safety
Clinical efficacy and safety of huperzine Alpha in treatment of mild to moderate Alzheimer disease, a placebo-controlled, double-blind, randomized trial (Zhang et al, 2002)
A double blind trial of 200 Alzheimer's patients. Half were given 400mcg daily of huperzine A and half a placebo for 12 weeks. Cognition, mood and behavior were significantly improved in those taking huperzine A. Mild adverse effect (insomnia and ankle edema) were observed in 3% of patients taking huperzine A.
Bioavailabilty
Green tea polyphenol (-)-epigallocatechin-3-gallate enhances the inhibitory effect of huperzine A on acetylcholinesterase by increasing the affinity with serum albumin (Zhang et al, 2009)
Huperzine A alone and Huperzine A with a green tea polyphenol EGCG (epigallocatechin-3-gallate) were administered to mice. The combined huperzine A/EGCG markedly enhance the inhibitory effect of huperzine A on acetylcholinesterase and increased its time of action. This means EGCG can be used to reduce the dosage required of huperzine A or increase its effects.