Cross-sectional and prospective relationships between physical morbidity and depression in older adolescents

To examine cross-sectional and prospective associations between major depressive disorder (MDD), physical morbidity (disease and injury), health-related reductions in activities, and functional impairment in adolescents.

Data on depression and health-related variables were available for a sample of 1,410 adolescents (aged 14 to 18 years) at point of entry into the study and approximately 1 year later.

Girls were more likely to have been treated for a disease and to have a health-related reduction in activities, whereas boys were more likely to have been treated for an injury. The expected cross-sectional associations were found between disease, reductions in activities, functional impairment, and depression, but the association between injury and depression was not significant. Prospective analyses suggest that functional impairment and disease are risk factors for future MDD and that MDD is a risk factor for future functional impairment and disease.

The robust prospective associations between MDD and functional impairment suggest that the impact of disease on depression is particularly strong when it disrupts important behavior patterns. Clinically, the results emphasize the importance of assessing health-related variables in depressed adolescents and of assessing depression in those with functional impairment or disease.