Preclinical Evidence and Possible Mechanisms of Extracts or Compounds from Cistanches for Alzheimer’s Disease

Currently, disease-modified strategies to prevent, halt or reverse the progress of Alzheimer’s disease (AD) are still lacking. Previous studies indicated extracts or compounds from Cistanches (ECC) exert a potential neuroprotective effect against AD. Thus, we conducted a preclinical systematic review to assess preclinical evidence and possible mechanisms of ECC in experimental AD. A systematical searching strategy was carried out across seven databases from their inceptions to July 2018. Twenty studies with 1696 rats or mice were involved. Neurobehavioral function indices as primary outcome measures were established by the Morris water maze test (n = 11), step-down test (n = 10), electrical Y-maze test (n = 4), step-through test (n = 3), open field test (n = 2) and passage water maze test (n = 1). Compared with controls, the results of the meta-analysis showed ECC exerted a significant effect in decreasing the escape latency, error times and wrong reaction latency in both the training test and the retention test, and in increasing the exact time and the percentage of time in the platform-quadrant and the number of platform crossings (all P<0.01). In conclusion, ECC exert potential neuroprotective effects in experimental AD, mainly through mechanisms involving antioxidant stress and antiapoptosic effects, inhibiting Aβ deposition and tau protein hyperphosphorylation and promoting synapse protection. Thus, ECC could be a candidate for AD treatment and further clinical trials.