Premorbid temperament as predictor of onset of depression: 23-year follow-up

Background: Previously Cloninger's temperament traits have been researched as a risk factor for depression mostly in cross-sectional studies. In these studies, especially high harm avoidance has been associated with an increased risk of depression. The main objective of this study was to investigate how temperament traits affect the risk of the onset of depression in a previously mentally healthy adult population. Methods: This study includes a follow-up period of 23 years from the age of 31 until 54 in the Northern Finland Birth Cohort 1966 Study. Temperament was measured at the 31-year follow-up using Temperament and Character Inventory (TCI). The outcome of the study was depressive disorder diagnosis during the follow-up in both sexes. To be able to take correlations between temperament traits we also did an analysis using temperament clusters. Results: Our sample size was 3999 individuals, out of which 240 were diagnosed with depression. For women an increase in the TCI score for novelty seeking (NS), harm avoidance (HA) or persistence (P) increased the risk of depression during the follow-up. For men only HA was a significant predictor of depression. An increase in reward dependence (RD) was found to reduce the risk of psychotic depression. In the analysis using the temperament clusters, the cluster including shy and pessimistic individuals was associated with risk for depression diagnosis in men. Conclusions: This prospective general population-based cohort study added to previous knowledge of high HA being a risk factor for depression, but it also found new associations such as higher P and NS