We assessed whether known risk factors for MDD were similar between definitions of depression22. Figure 2a-g shows the mean effect (odds ratio, OR) with confidence intervals of each of the following: sex23,24, age25, educational attainment26-28, socioeconomic status29, neuroticism24,30, experience of stressful life events in the 2 years leading up to the baseline assessment and cumulative traumatic life events preceding assessment31,32 (Supplementary Note and Supplementary Table 12). Estimates of the risk factor effect sizes differed substantially, and often highly significantly, as shown by the confidence intervals in Fig. 2. These may reflect differences in methods of ascertainment or underlying pathology between definitions of depression. Next, we asked whether differences in risk factors could be used to classify definitions of depression. We applied a clustering algorithm and found that all minimal phenotyping definitions of depression clustered separately from strictly defined MDD (Fig. 2h).
