Influences of childhood family factors on depressive symptoms in adolescence and early adulthood: A Danish longitudinal study.

Aims: The study examined the timing of family socio-economic factors during early (aged 0-8 years) and late (aged 9-14 years) childhood, as well as psychosocial variables in relation to depressive symptoms at the ages of 15, 18 and 21. Methods: This prospective cohort study included 3014 young people from western Denmark. Exposure variables were equivalised household income (income), mother's educational level and mother's labour market participation (LMP), derived from registers and self-reported variables family functioning, subjective social status and negative life events. The outcome variable was depressive symptoms. Associations were analysed using logistic regression, adjusted for other exposure variables and sex. Results: In early childhood, mother's low LMP was associated with higher risk of depressive symptoms at the age of 15, whereas mother's low educational level and lower income was associated with higher risk of depressive symptoms at the age of 21. In late childhood, lower income, mother's low educational level and mother's low LMP was associated with higher risk of depressive symptoms at the ages of 15 and 21. Poorer family functioning was associated with depressive symptoms at the age of 15-21, with estimates ranging from 1.8 to 2.6. Reporting two or more negative life events were associated with depressive symptoms at the ages of 15 and 18. Conclusions: Timing of low income, mother's low educational level and mother's low LMP during childhood in relation to future depressive symptoms in the offspring appears to be of some importance in this Danish youth cohort. Family functioning and negative life events were the most stable risk factors for depressive symptoms. Results should, however, be interpreted with caution due to the risk of reverse causality.