title: Sex differences in fear conditioning in posttraumatic stress disorder.
abstract: BACKGROUND
  Women are twice as likely as men to develop Posttraumatic Stress Disorder (PTSD). Abnormal acquisition of conditioned fear has been suggested as a mechanism for the development of PTSD. While some studies of healthy humans suggest that women are either no different or express less conditioned fear responses during conditioning relative to men, differences in the acquisition of conditioned fear between men and women diagnosed with PTSD has not been examined.
  
  
  METHODS
  Thirty-one participants (18 men; 13 women) with full or subsyndromal PTSD completed a fear conditioning task. Participants were shown computer-generated colored circles that were paired (CS+) or unpaired (CS-) with an aversive electrical stimulus and skin conductance levels were assessed throughout the task.
  
  
  RESULTS
  Repeated measures ANOVA indicated a significant sex by stimulus interaction during acquisition. Women had greater differential conditioned skin conductance responses (CS + trials compared to CS- trials) than did men, suggesting greater acquisition of conditioned fear in women with PTSD.
  
  
  CONCLUSIONS
  In contrast to studies of healthy individuals, we found enhanced acquisition of conditioned fear in women with PTSD. Greater fear conditioning in women may either be a pre-existing vulnerability trait or an acquired phenomenon that emerges in a sex-dependent manner after the development of PTSD. Characterizing the underlying mechanisms of these differences is needed to clarify sex-related differences in the pathophysiology of PTSD.
authors.affiliation: University of California, San Francisco, San Francisco, CA 94121, United States. Sabra.Inslicht@ucsf.edu
authors.forename: Sabra S
authors.initials: SS
authors.lastname: Inslicht
authors.forename: Thomas J
authors.initials: TJ
authors.lastname: Metzler
authors.forename: Natalia M
authors.initials: NM
authors.lastname: Garcia
authors.forename: Suzanne L
authors.initials: SL
authors.lastname: Pineles
authors.forename: Mohammed R
authors.initials: MR
authors.lastname: Milad
authors.forename: Scott P
authors.initials: SP
authors.lastname: Orr
authors.forename: Charles R
authors.initials: CR
authors.lastname: Marmar
authors.forename: Thomas C
authors.initials: TC
authors.lastname: Neylan
mesh_terms: D000328:Adult; D003214:Conditioning, Classical / Q000502:physiology*; D004566:Electrodes; D005239:Fear / Q000502:physiology*; D005260:Female; D005712:Galvanic Skin Response / Q000502:physiology*; D006801:Humans; D008297:Male; D012727:Sex Characteristics; D013313:Stress Disorders, Post-Traumatic / Q000503:physiopathology*; D014481:United States; D014493:United States Department of Veterans Affairs