title: A single administration of testosterone reduces fear-potentiated startle in humans.
abstract: BACKGROUND
  Ample evidence from animal research indicates that the gonadal steroid hormone testosterone has fear-reducing properties. Human data on this topic, however, are scarce and far less unequivocal. The present study therefore aimed to scrutinize anxiolytic effects of a single dose of testosterone, using a direct physiological index of fear in humans.
  
  
  METHODS
  Twenty healthy female participants were tested in a double-blind, placebo-controlled crossover design involving sublingual administration of a single dose of testosterone. Four hours after intake, we assessed effects on baseline startle and fear-potentiated startle in a verbal threat-of-shock paradigm.
  
  
  RESULTS
  In accordance with predictions, testosterone administration resulted in reduced fear-potentiated startle, without affecting baseline startle.
  
  
  CONCLUSIONS
  This study provides direct evidence that a single dose of testosterone reduces fear in humans. The relationship of this effect to previous research on anxiolytic effects of benzodiazepines, as well as possible mechanisms of action, is discussed.
authors.affiliation: Helmholtz Institute, Utrecht University, Utrecht, The Netherlands. E.Hermans@fss.uu.nl
authors.forename: Erno J
authors.initials: EJ
authors.lastname: Hermans
authors.forename: Peter
authors.initials: P
authors.lastname: Putman
authors.forename: Johanna M
authors.initials: JM
authors.lastname: Baas
authors.forename: Hans P
authors.initials: HP
authors.lastname: Koppeschaar
authors.forename: Jack
authors.initials: J
authors.lastname: van Honk
mesh_terms: D000293:Adolescent; D000328:Adult; D000704:Analysis of Variance; D000728:Androgens / Q000008:administration & dosage*; D018592:Cross-Over Studies; D004311:Double-Blind Method; D004576:Electromyography / Q000379:methods; D004597:Electroshock / Q000009:adverse effects; D005239:Fear / Q000187:drug effects*; D005260:Female; D006801:Humans; D011930:Reaction Time / Q000187:drug effects; D013216:Reflex, Startle / Q000187:drug effects*; D013739:Testosterone / Q000008:administration & dosage*
chemical_list: D000728:Androgens; D013739:Testosterone