The Stress Sensitization Model

The stress sensitization model was developed to explain the mechanism through which the relationship between stress and affective disorder onsets changes across the course of the disorder. The model posits that individuals become sensitized to stress over time, such that the level of stress needed to trigger episode onsets becomes increasingly lower with successive episodes. The stress sensitization model has accrued empirical support in the context of major depression and to a lesser extent in bipolar spectrum disorders. Furthermore, expanding upon the original stress sensitization model, research also indicates that early adversity (i.e., early childhood experiences) sensitizes individuals to subsequent proximal stress, increasing risk for psychopathology. In this chapter, the theoretical background underlying the stress sensitization model is reviewed, and research evidence investigating stress sensitization is evaluated. In addition, moderators and mechanisms of stress sensitization effects are reviewed, and recommendations for future research are provided.