title: Signs of mood and anxiety disorders in chimpanzees.
abstract: BACKGROUND
  In humans, traumatic experiences are sometimes followed by psychiatric disorders. In chimpanzees, studies have demonstrated an association between traumatic events and the emergence of behavioral disturbances resembling posttraumatic stress disorder (PTSD) and depression. We addressed the following central question: Do chimpanzees develop posttraumatic symptoms, in the form of abnormal behaviors, which cluster into syndromes similar to those described in human mood and anxiety disorders?
  
  
  RESULTS
  In phase 1 of this study, we accessed case reports of chimpanzees who had been reportedly subjected to traumatic events, such as maternal separation, social isolation, experimentation, or similar experiences. We applied and tested DSM-IV criteria for PTSD and major depression to published case reports of 20 chimpanzees identified through PrimateLit. Additionally, using the DSM-IV criteria and ethograms as guides, we developed behaviorally anchored alternative criteria that were applied to the case reports. A small number of chimpanzees in the case studies met DSM-IV criteria for PTSD and depression. Measures of inter-rater reliability, including Fleiss' kappa and percentage agreement, were higher with use of the alternative criteria for PTSD and depression. In phase 2, the alternative criteria were applied to chimpanzees living in wild sites in Africa (n = 196) and chimpanzees living in sanctuaries with prior histories of experimentation, orphanage, illegal seizure, or violent human conflict (n = 168). In phase 2, 58% of chimpanzees living in sanctuaries met the set of alternative criteria for depression, compared with 3% of chimpanzees in the wild (p = 0.04), and 44% of chimpanzees in sanctuaries met the set of alternative criteria for PTSD, compared with 0.5% of chimpanzees in the wild (p = 0.04).
  
  
  CONCLUSIONS
  Chimpanzees display behavioral clusters similar to PTSD and depression in their key diagnostic criteria, underscoring the importance of ethical considerations regarding the use of chimpanzees in experimentation and other captive settings.
authors.affiliation: Physicians Committee for Responsible Medicine, Washington, DC, United States of America. hferdowsian@pcrm.org
authors.forename: Hope R
authors.initials: HR
authors.lastname: Ferdowsian
authors.forename: Debra L
authors.initials: DL
authors.lastname: Durham
authors.forename: Charles
authors.initials: C
authors.lastname: Kimwele
authors.forename: Godelieve
authors.initials: G
authors.lastname: Kranendonk
authors.forename: Emily
authors.initials: E
authors.lastname: Otali
authors.forename: Timothy
authors.initials: T
authors.lastname: Akugizibwe
authors.forename: J B
authors.initials: JB
authors.lastname: Mulcahy
authors.forename: Lilly
authors.initials: L
authors.lastname: Ajarova
authors.forename: Cassie Meré
authors.initials: CM
authors.lastname: Johnson
mesh_terms: D000818:Animals; D001007:Anxiety / Q000503:physiopathology*; D005260:Female; D008297:Male; D019964:Mood Disorders / Q000503:physiopathology*; D002679:Pan troglodytes