What Do EURO-D Scores Capture? Disentangling Trait and State Variances in Depression Symptoms Across the Adult Life Span in Nine European Nations

The primary purposes of the present study were to determine (a) whether the EURO-D measures trait (i.e., time-invariant) versus state (i.e., time-variant) aspects of depression and (b) whether these aspects are stable across countries and ages. In five waves of the SHARE survey (a nationally representative Survey of Health, Ageing, and Retirement in Europe), we estimated trait-state-occasion models (TSO), including multiple-nation TSO, based on data from nine European nations over a 10-year period. Also, we used local structural equation modeling to test for the moderating effects of age on the TSO parameters. Our main findings were: (a) there were differences in the trait/state variances of depressive symptoms across nations. The amount of trait variance was above 60% for Belgium, Denmark, and France. It was between 50% and 60% for Austria, Germany, Sweden, and Switzerland, while it was below 50% for Italy and Spain. (b) The effects of trait and state were almost equally the source of variance for depression symptoms across ages, with a slight advantage for the effects of trait (56% of the variance). This trend showed substantial stability across the adult life course (from age 40 up to age 95).