AN EVALUATION OF THE USE OF DEFEAT-INDUCED LOSS OF STATUS IN THE RAT AS A MODEL OF LOSS OF SELF-ESTEEM AND DEPRESSION IN HUMANS

Social defeat by Tryon Maze Dull rats, resulting in loss of rank of a previously dominant rat, has recently been advanced as a model of loss of self-esteem and depression in humans. However, before loss of rank in animals can be assessed as a model of human depression, certain re quirements must be fulfilled: (1) a situation must be developed in whi ch rank can be determined, and this assessment must, under normal circ umstances, remain stable if it is to be the baseline against which exp erimental manipulations are measured; (2) it must be established that defeat of a dominant animal does indeed cause a change in rank for tha t animal; and (3) once these practical requirements have been fulfille d, to be a ''model of depression,'' antidepressant treatment must be s een to reverse the loss of rank caused by defeat. Each of these points is considered in turn. (1) So far, a situation has not been discovere d in which social hierarchies are produced that are both unequivocal a nd stable. (2) Defeat seems to have very variable effects, the variabi lity being most likely due to natural variation in the quality of the defeat ''experience'' for the recipient. (3) Antidepressant treatment has not yet been shown to reverse the effects of defeat for more than a single test session. In addition, it has not been demonstrated that loss of rank actually produces a lowering of self-esteem in the animal as opposed to helplessness. If the change in self-perception does not change the value the animal attributes to itself, but rather the leve l of ability the animal attributes to itself, then the model breaks do wn. Consequently, at this time, the predictive validity of the model h as not yet been established. Furthermore, its construct validity may b e low In summary, much more work is required before defeat-induced los s of status in the rat can be properly assessed as a model of loss of self-esteem and depression in humans, although it may be bedevilled by theoretical weaknesses even at this early stage. (C) 1998 Wiley-Liss, Inc.