Four RCTs were included in the review (n=474 participants). Sample sizes ranged from 65 to 197. All RCTs described the method of randomisation, two were single blind, two double blind. Withdrawals and drop-outs were reported in two RCTs and only one RCT reported ITT data.
Huperzine A was associated with a beneficial effect on mini-mental state examination (MMSE) scores (WMD 3.52, 95% CI 2.23 to 4.80) and activities of daily living scale (ADL) scores (WMD -4.50, 95% CI -7.05 to -1.96) compared with placebo (four RCTs). Both outcomes were associated with significant heterogeneity (MMSE, Q=11.1 and p=0.01; ADL, Q=11.4 and p=0.0098).
The regression analysis showed significantly better efficacy over time for mean change in MMSE in the huperzine A group and a similar but non-significant trend for time effect on mean ADL.
Some mild peripheral cholinergic side effects (such as nausea or vomiting and diarrhoea) were more likely to occur in the huperzine A group than placebo, but this difference was not significant.