Non-human

Psychopathology in non-human primates has been studied since the mid 20th century. Over 20 behavioral patterns in captive chimpanzees have been documented as (statistically) abnormal for their frequency, severity or oddness - some of which have also been observed in the wild. Captive great apes show gross behavioral abnormalities such as stereotypy of movements, self-mutilation, disturbed emotional reactions (mainly fear or aggression) towards companions, lack of species-typical communications, and generalized learned helplessness. In some cases such behaviors are hypothesized to be equivalent to symptoms associated with psychiatric disorders in humans such as depression, anxiety disorders, eating disorders and post-traumatic stress disorder. Concepts of antisocial, borderline and schizoid personality disorders have also been applied to non-human great apes.

The risk of anthropomorphism is often raised with regard to such comparisons, and assessment of non-human animals cannot incorporate evidence from linguistic communication. However, available evidence may range from nonverbal behaviors - including physiological responses and homologous facial displays and acoustic utterances - to neurochemical studies. It is pointed out that human psychiatric classification is often based on statistical description and judgment of behaviors (especially when speech or language is impaired) and that the use of verbal self-report is itself problematic and unreliable.