Health Follow-up’ questionnaire (MHQ)17 based on the Composite International Diagnostic Interview Short Form (CIDI-SF)18, which included the Diagnostic and Statistical Manual of Mental Disorders, Fifth Edition (DSM-5) criteria for MDD (Supplementary Note, Supplementary Fig. 1 and Supplementary Table 2). None of the definitions used trained interviewers applying structured clinical interviews, and only the last applied operationalized criteria, including symptoms, length of episode (more than 2 weeks) and impaired social, occupational or educational function. From here on, we refer to the first three definitions as ‘minimal’, the fourth as ‘EMR-based, and the fifth as ‘strictly’ defined MDD (Supplementary Note). We also included a category of participants who met the help-seeking definition (part of broad depression in Howard et al.3) but failed to meet the symptom-based definition (as they had neither of the two cardinal symptoms of depression: depressed mood or a loss of interest or pleasure in daily activities for more than 2 weeks). We refer to this group as ‘no-MDD’ (described in detail in the Supplementary Note and Supplementary Table 3). Figure 1 outlines the different diagnostic categories and the number of samples that each group contained.
