Signs of Mood and Anxiety Disorders in Chimpanzees

Abstract

BackgroundIn 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?Methodology/Principal FindingsIn 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/SignificanceChimpanzees 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.

Relation between the level of self-mutilation and theconcentration of fecal metabolites of glucocorticoids incaptive chimpanzees (Pan troglodytes)

“…Self-mutilation presented the highest frequency of occurrence of abnormal behaviors (mean 38.28% ± 3.98), in contrast with the findings of Ferdowsian (2011), in which coprophagy was the abnormal behavior with a higher prevalence. The frequency of occurrence of abnormal behaviors (13.45% ±2.76), can also be considered higher comparing to the findings by Bloomsmith and Lambet (1995) and Ferdowsian (2011) however, no work had previously related the occurrence of abnormal behaviors with concentrations of glucocorticoids.…”

“…Self-mutilation has been widely studied as an abnormal behavior in chimpanzees (Birkett & Fisher-Newton 2011, Ferdowsian 2011) and quantitative studies of these behaviors can demonstrate the effects of captivity among this specie (Birkett & Fisher-Newton 2011).…”

Managing dingoes on Fraser Island: culling, conflict, and an alternative

“…Conceptualising animals as purely mechanistic has long since been supplanted by a more sophisticated understanding that animals feel, make choices and form deep emotional bonds (Johnson 1991;Haber 1996;Rogers and Kaplan 2003;Bekoff 2007;Ferdowsian et al 2011). Animals have been shown to experience trauma and this can be triggered by loss of family or companions, by abuse and resulting stress (Ferdowsian et al 2011).…”

“…Animals have been shown to experience trauma and this can be triggered by loss of family or companions, by abuse and resulting stress (Ferdowsian et al 2011). One of the mechanisms of coping with trauma is aggression, born sometimes of fearfulness or confusion and denoting, in its true meaning, a dysfunctional behaviour that carries little to no benefit for the individual displaying it (Rogers and Kaplan 2003).…”

Emotion as an Intervening Variable in Understanding the Cognitive and Social Complexity and Well-Being of Chimpanzees

“…Some studies have attempted to estimate the hypothetical emotional states of chimpanzees based on human observers' subjective ratings (Ferdowsian et al, 2011;King & Landau, 2003;Weiss et al, 2009). For example, Weiss et al (2009) asked personnel who were familiar with subject chimpanzees to rate them using questionnaires similar to those commonly used in human studies of subjective well-being; these have included questions about the degree to which the general moods of subject chimpanzees are positive/negative and the extent to which chimpanzees found social interactions to be pleasurable or satisfying.…”