Here are some studies:
Cistanches Herba enhances learning and memory by inducing nerve growth factor. https://www.ncbi.nlm.nih.gov/pubmed/20849880
Antifatigue activity of phenylethanoid-rich extract from Cistanche deserticola. https://www.ncbi.nlm.nih.gov/pubmed/19610039
The hypocholesterolemic effects of Cistanche tubulosa extract, a Chinese traditional crude medicine, in mice. https://www.ncbi.nlm.nih.gov/pubmed/19938221