A preliminary investigation on the evaluation of psychopathologies in a group of ex-pet and ex-performer chimpanzees (Pan troglodytes): A rating approach based on the Diagnostic and Statistical Manual of Mental Disorders (DSM)

The diagnosis of psychopathologies in nonhuman primates has received increasing interest in the last decade. However, only a limited number of categories of pathology have been diagnosed in some chimpanzees exclusively by using adapted versions of the Diagnostic and Statistical Manual of Mental Disorders (DSM). With this in mind, we have created a questionnaire for the assessment of psychopathologies in 23 rescued ex-performer and ex-pet chimpanzees, based on an inclusion-exclusion adaptation of the fifth edition of the DSM. A total of 70 items were retained for the Chimpanzee Psychopathology Questionnaire in accordance with 3 main criteria: deleting those that could not be applied to the subjects, retaining those that could be applied, and adapted when needed. Principal component analysis and regularized exploratory factor analysis revealed 9 statistically significant factors with acceptable standards of interrater reliability and validity, accounting for 70.78 % of the variance. The factors obtained were clear and similar to some of the main categories of diagnosis for humans. Nevertheless, the limitation of the sample, the subjectivity in the creation of the questionnaire, as well as the theoretical and methodological challenges of the adaptation of the DSM to chimpanzees, led to the fact that this research should be considered as a first contact study on the identification of disorder categories in a group of chimpanzees. The main purpose of this study is to start a debate to promote research on psychopathology in chimpanzees and other animals. Likewise, it is important to emphasize that the diagnosis of psychiatric disorders in chimpanzees could be translated to important pragmatic aspects for the species related to awareness, legal implications, welfare, and comparative psychopathology.