The precursor model views personality as an early manifestation or “forme fruste” of depressive disorder. Like the common cause and continuum/spectrum accounts, the precursor model posits that personality and depressive disorders are caused by similar etiologic factors. Also like the continuum/spectrum account, it implies considerable phenomenologic similarity between the relevant trait and depression. However, the precursor model differs from both of these other models in that it assumes a particular developmental sequence, with the personality traits being evident prior to the onset of depressive disorder. In other words, both the common cause and continuum/spectrum models assume a fixed clinical expression as traits or disorder, whereas the precursor model implies escalation from traits to disorder within individuals over time. Support for the precursor model would come from evidence that the trait and depression are associated with the same etiological influences and that individuals with high levels of the trait are at increased risk for developing the disorder over time.2
