TOWARDS A SOCIOBIOLOGICAL MODEL OF DEPRESSION - A MARSUPIAL MODEL (PETAURUS BREVICEPS)

Background. This is a sociobiological approach to depression using hie rarchy and its hypothesised relevance to self-esteem in the marsupial sugar glider (Petaurus breviceps). Method. Differential access to reso urces between the dominant and submissive animal is measured by observ ation in four stable colonies. The dominant animals from two of these colonies are then introduced into the other two, resulting in the tran sferred former dominants becoming subordinate. Behavioural and biochem ical measures relevant to depression and involving access to resources are then repeated. These measures include eating, drinking, social an d sexual access, motility, grooming and biochemical estimates of corti sol and testosterone.Results. Subordinate animals have significantly l ess access to resources, both in the stable colony and when the former ly dominant animals become subordinate. Conclusions. A sociobiological approach using a hierarchy model equating resource-holding potential with self-esteem, exemplified by this study, may provide new concepts and insights into the phenomenology and pathophysiology of depression. It allows comparisons to be made between animal behaviour and cogniti on: the lack of such has been a major difficulty in animal studies hit herto. The findings are possibly more relevant to dysthymia than to af fective disorder and imply a relationship between low resource-holding potential in sub-human animals as a phylogenetic antecedent of some o f the cognitive and affective aspects of depression in man.