In the original report by Caspi and colleagues [15], a depression outcome at age 26 was assessed using the Diagnostic Interview Schedule [43], yielding a diagnosis of a major depressive episode according to DSM-IV criteria, as well as a continuous measure of depressive symptoms. Stressful life events occurring over a five-year period were assessed retrospectively when study members were aged 26. Subjects with a diagnosis of depression prior to the five-year window were excluded. Stressful events were summed to create a five-level ordinal variable (no life events, one, two, three, and four or more events). Exposure to childhood maltreatment was also examined at three levels (no, probable, and likely maltreatment).
