Stress, neurochemical substrates, and depression: Concomitants are not necessarily causes

Depression: an inability to adapt to one's perceived life distress?

A comprehensive biopsychosocial distress adaptation model of depression in which neurochemical shortages are awarded a necessary but insufficient status is proposed. In context of this model, depression is seen as a function of inadequate behavioural, psychological, socioenvironmental and biological coping resources (all of which may be partly a function of genetic factors) for managing one's individually appraised level of life distress. It is further hypothesized that the physiological symptoms of depression arise as a result of a lack of available neurotransmitters to contend with stressors as well as maintain the normal functioning of the individual. Unlike many other theories, this distress adaptation model may account for several of the demographics of depression.

The validity of animal models of depression

Eighteen animal models of depression are reviewed in relation to three sets of validating criteria. Of the 18 models, five could only be assessed for predictive validity, seven could be assessed for predictive and face validity, and six could potentially have predictive, face and construct validity. Some traditional models (reserpine reversal, amphetamine potentiation) are rejected as invalid; the models with the highest overall validity are the intracranial self-stimulation, chronic stress and learned helplessness models in rats, and the primate separation model.