The nature of relations between these personality traits and depression is complex, and our understanding is still limited. N/NE, the most widely studied personality trait in depression, raises challenging conceptual and methodological issues due to the overlap between some of its features and depressive symptoms (Ormel et al. 2004b). Nonetheless, this cannot completely explain the association between these constructs (Tang et al. 2009). N/NE is moderately influenced by clinical state (the concomitants model), shares common etiological influences with MDD (common cause, continuum/spectrum, and precursor models), predicts the subsequent onset of MDD (precursor and predisposition models), and influences the course of depression (pathoplasticity model). In addition, N/NE appears to contribute to subsequent stress and adversity and increases the risk of depression in the face of negative life events (predisposition model). Finally, it may also be changed by experience of MDD episodes (consequences model), but the evidence for this is weaker and less consistent.
