title: Amygdala volume in combat-exposed veterans with and without posttraumatic stress disorder: a cross-sectional study.
abstract: BACKGROUND
  Data from animal models demonstrate a link between stress exposure and hypertrophic changes in the amygdala; however, studies of adults with posttraumatic stress disorder (PTSD) have failed to find analogous structural alterations.
  
  
  OBJECTIVE
  To compare amygdala volumes between a sample of combat veterans with and without PTSD (analysis 1) and examine whether our observation of larger amygdala volume in individuals with PTSD could be accounted for by the presence of trauma exposure in childhood and the severity of combat exposure in adulthood (analysis 2).
  
  
  METHODS
  Cross-sectional magnetic resonance imaging.
  
  
  METHODS
  Veterans Affairs Palo Alto Health Care System Inpatient Trauma Recovery Program and Veterans Affairs New England Health Care System Outpatient PTSD program.
  
  
  METHODS
  Ninety-nine combat-exposed veterans from the Vietnam Conflict or the Persian Gulf War who had been exposed to substantial military operational stress.
  
  
  METHODS
  Amygdala volume adjusted for total cerebral volume, Life Events Checklist, and the Combat Exposure Scale.
  
  
  RESULTS
  Analysis 1 indicated that combat-exposed individuals with PTSD exhibited larger total amygdala volume compared with their non-PTSD counterparts (99 individuals, P = .047). Analysis 2 indicated that greater severity of combat exposure (87 individuals, P = .02), as well as the interaction between the presence of early life trauma and the severity of combat exposure (87 individuals, P = .008), were significantly associated with smaller total amygdala volume. The PTSD diagnosis continued to explain larger amygdala volume (87 individuals, P = .006).
  
  
  CONCLUSIONS
  Posttraumatic stress disorder is associated with enlarged amygdala volume, above the variance accounted for by a history of early life trauma and severity of adult trauma exposure. The discrepancy between our and prior findings may be explained by variability in these trauma indices in previous investigations. These findings support additional study of amygdala structure in human stress disorders and further delineation of the role of early and adult trauma on associated neurologic changes.
authors.affiliation: Department of Psychology, Ryerson University, Toronto, Ontario, Canada. jkuo@psych.ryerson.ca
authors.forename: Janice R
authors.initials: JR
authors.lastname: Kuo
authors.forename: Danny G
authors.initials: DG
authors.lastname: Kaloupek
authors.forename: Steven H
authors.initials: SH
authors.lastname: Woodward
mesh_terms: D000328:Adult; D000679:Amygdala / Q000473:pathology*; D002140:California; D003130:Combat Disorders / Q000175:diagnosis / Q000473:pathology* / Q000523:psychology; D003430:Cross-Sectional Studies; D005260:Female; D047830:Gulf War; D006801:Humans; D008016:Life Change Events; D008279:Magnetic Resonance Imaging / Q000295:instrumentation / Q000379:methods*; D008297:Male; D008875:Middle Aged; D009511:New England; D012720:Severity of Illness Index; D013313:Stress Disorders, Post-Traumatic / Q000175:diagnosis / Q000473:pathology* / Q000523:psychology; D014481:United States; D014493:United States Department of Veterans Affairs; D014728:Veterans / Q000523:psychology*; D047829:Vietnam Conflict