What characteristics are associated with earlier onset of first depressive episodes: A 16-year follow-up of a national population-based cohort

This study examined characteristics associated with earlier onset of first depressive episodes. A nationally representative Canadian sample was randomly selected and followed from 1994 to 2011. At baseline complete data on depression history (Yes/No) and related diseases was available for 12,227 study subjects. Proportional hazard models were used. Meta-analyses were also applied to sync results across studies. Being younger, a woman, a Caucasian, a regular smoker, and having a chronic disease were significantly associated with the expedited trajectory for the onset of the first depressive episode. People were at the greater risk of having earlier onset of first depressive episodes at the 2-year follow-up (p < 0.001), with the risk declining after four years (p < 0.001). Women and men had different sets of characteristics associated with earlier onset of first depressive episodes. In meta-analyses, those having a chronic disease (HRpooled = 1.31) and being a woman (HRpooled = 1.43) were more likely to have earlier onset of first depressive episodes. This study provides solid evidence on the timing effect of these characteristics on first depressive episodes. Approaches focused on these identified risk characteristics should be prioritized to reduce the risk and postpone the onset of major depressive episode.