Depressive symptoms in adolescents with chronic fatigue syndrome (CFS): Are rates higher than in controls and do depressive symptoms affect outcome?

Previous research has indicated that co-morbid depression is common in adolescents with chronic fatigue syndrome (CFS). We sought to compare the characteristics of depressive symptoms in adolescents with CFS to those of healthy controls (HCs) and illness controls (adolescents with asthma). Case-control study nested within a prospective clinical cohort. A total of 121 adolescents with CFS who attended an initial assessment at two specialist CFS units completed the Children's Depression Inventory (CDI). Their responses were compared to 80 HCs and 27 adolescents with asthma (illness controls). The clinical cohort of adolescents with CFS completed questionnaires at assessment, and those who were seen subsequently for treatment at the CFS unit (68%) completed the measures again at their first treatment session. CFS participants scored significantly higher on all the depression subscales than participants with asthma and HCs. Depression score explained 11% of the variance in subsequent fatigue, but only 1.9% of the variance in physical functioning. Depression score also explained most (68%) of the variance in subsequent depression. Depressive symptoms are more prominent in adolescents with CFS than in HCs or illness controls. These symptoms also appear to remain over time during a naturalistic follow-up where no treatment was provided. This highlights the need for further research into depression in CFS, including stratifying treatment outcomes by depression status to determine what is effective at addressing these symptoms.