Development of health and depressive symptoms among Danish adolescents—Socioeconomic differences and effects of life-style

While the existence of social inequality in health in childhood as well as among adults is well established, research of mechanisms underlying this inequality is still sparse. The study aim was to report on the development of self-rated health and depressive symptoms from age 15 to18 years in a cohort study of Danish adolescents. Methods: The cohort comprised 3,681 individuals born in 1989, 3058 individuals answered the baseline questionnaire in 2004, and 2400 responded to a follow-up questionnaire in 2007, with 2181 individuals participating in both rounds (59% of the original cohort). Social background information of the participants was derived from a national register. For the analysis two variables indicating change in the two health indicators was computed by subtracting the 2007 levels of the variables from the levels experienced in 2004. Results: After 3 years, mean self-rated health (SRH) deteriorated slightly in adolescents (-0.24; 95% CI = -0.28 to -0.19) across all socioeconomic status (SES) groups and depressive symptoms increased (0.64; 95% CI = 0.52 to 0.75). High household income was protective for decrease in SRH (0.62; 0.43 - 0.91). Negative lifestyle changes were associated with poorer SRH and more depressive symptoms. Conclusions: Self-rated health and depressive symptoms changed to the worse among Danish adolescents from age 15 to 18 years. Negative changes in several lifestyle factors were found to accompany the deterioration of health. This result stresses the intrinsic relationship between lifestyle changes and health and the possible positive effect of maintaining and enhancing positive lifestyle factors.