title: Effect of a single dose of dextromethorphan on psychomotor performance and working memory capacity.
abstract: BACKGROUND
  Previous studies show that the prolonged use of dextromethorphan produces cognitive deterioration in humans.
  
  
  OBJECTIVE
  The aim of this study was to investigate the effect of a single dose of dextroemthrophan on psychomotor performance and working memory capacity.
  
  
  METHODS
  This is a randomized, double-blind, controlled, and prospective study. Thirty-six (17 women, 19 men) medical students enrolled in the study; half of them (7 women, 11 men) were given placebo, while the other half (10 women, 8 men) received dextromethorphan. The choice reaction time, critical flicker fusion threshold, and N-back working memory task were measured before and after 2 h of taking the drugs.
  
  
  RESULTS
  Dextromethorphan showed a significant deterioration in the 3-back working memory task (P<0.05). No significant changes were seen as regards the choice reaction time components (total, recognition, motor) and critical flicker fusion threshold (P>0.05). On the other hand, placebo showed no significant changes as regards the choice reaction time, critical flicker fusion threshold, and N-back working memory task (P>0.05).
  
  
  CONCLUSIONS
  A single dose of dextromethorphan has no effect on attention and arousal but may significantly impair the working memory capacity.
authors.affiliation: Department of Pharmacology, College of Medicine, Al-Mustansiriya University, Baghdad, Iraq.
authors.forename: Hayder M
authors.initials: HM
authors.lastname: Al-Kuraishy
authors.forename: Ali I
authors.initials: AI
authors.lastname: Al-Gareeb
authors.forename: Ammar Waham
authors.initials: AW
authors.lastname: Ashor