Social differences in diagnosed depression among adolescents in a Swedish population based cohort.

Background: Population based research regarding social differences in diagnosed depression in adolescence is sparse. In this study unique material containing in-and outpatient data was used to determine if low social position in childhood increases the risk of diagnosed depression in adolescence. To further examine this association, gender differences and interactions were explored.
Methods: The study population was extracted from the Stockholm Youth Cohort (SYC), a register based cohort containing psychiatric care for all young people in Stockholm County and information about social position. For the purpose of this study, all in the SYC who turned 13 years old during 2001-2007, in total 169,262 adolescents, were followed up in 2005-2011 for diagnoses of depression until age 18. Associations were estimated with Cox regression models and presented as Hazard Ratios (HR).
Results: The risk of diagnosed depression was higher for adolescents with parents with low education (HR = 1.1, CI = 1.0-1.2) and medium education (HR = 1.1, CI = 1.1-1.2) compared to high as well as for those with lower household income (for example, medium low, HR = 1.2, CI = 1.1-1.3) and for those with parents who received an unemployment benefit (HR = 1.3, CI = 1.2-1.4). No differences were found for those with the lowest household income compared to those with the highest level. Adolescents with parents born outside the Nordic countries had a lower risk of diagnosed depression (HR = 0.7, CI = 0.6-0.7). An interaction effect was found between gender and parental education.
Conclusions: Social differences were found but the magnitude was modest and gender differences small.