Huperzine A

Multiple Chinese RCTs report memory improvements in Alzheimer's patients, though trial quality is variable. One of the more evidence-backed natural nootropics.

A rough internal score reflecting quantity, quality, and consistency of human evidence. Not a clinical recommendation.

A Cochrane review found beneficial effects on cognitive function in AD patients but noted methodological concerns in the included Chinese trials. Phase II trials in the US showed mixed results.

• Potent and reversible acetylcholinesterase inhibition
• Multiple trials show memory improvement in AD
• Neuroprotective against glutamate toxicity in vitro

Typical range is 50–200 mcg twice daily. Cycle use (e.g., 2–4 weeks on, 1 week off) is commonly recommended due to long half-life.

• Nausea
• Diarrhea
• Vivid dreams
• Muscle cramps

Potent AChE inhibitor — avoid stacking with donepezil, galantamine, or other cholinesterase inhibitors. Contraindicated with certain cardiac arrhythmias.

Most positive trials are from China with methodological limitations. US Phase II results were less convincing.

• Memory60
• Focus50