title: Central additive effect of Ginkgo biloba and Rhodiola rosea on psychomotor vigilance task and short-term working memory accuracy.
abstract: OBJECTIVE
  The present study investigates the effect of combined treatment with Ginkgo biloba and/or Rhodiola rosea on psychomotor vigilance task (PVT) and short-term working memory accuracy.
  
  
  METHODS
  A total number of 112 volunteers were enrolled to study the effect of G. biloba and R. rosea on PVT and short-term working memory accuracy as compared to placebo effects, the central cognitive effect was assessed by critical flicker-fusion frequency, PVT, and computerized N-back test.
  
  
  RESULTS
  Placebo produced no significant effects on all neurocognitive tests measure P > 0.05 in normal healthy volunteers, G. biloba or R. rosea improve PVT and low to moderate working memory accuracy, The combined effect of R. rosea and G. biloba leading to more significant effect on PVT, all levels of short-term working memory accuracy and critical fusion versus flicker P < 0.01, more than of G. biloba or R. rosea when they used alone.
  
  
  CONCLUSIONS
  The combined effect of R. rosea and G. biloba leading to a more significant effect on cognitive function than either G. biloba or R. rosea when they used alone.
authors.affiliation: Department of Pharmacology, Toxicology and Medicine College of Medicine Al-Mustansiriya University, P.O. Box 14132, Iraq, Baghdad.
authors.forename: Hayder M
authors.initials: HM
authors.lastname: Al-Kuraishy
keywords: Ginkgo biloba; Rhodiola rosea; neurocognitive tests