Prevalence, characteristics, and treatment outcomes of fatigue in adolescent depression: Findings from an exploratory secondary analysis of the IMPACT study

Introduction: Fatigue is a highly disabling symptom of depression that is associated with numerous detrimental outcomes and is not effectively treated in adults. Outcomes may be similar for adolescents with depression, but minimal research has been conducted in this area. Little is known about whether current psychological treatments for depression address the symptom of fatigue, nor what clinical or demographic characteristics may be indicative of its presence.
Methods: An exploratory secondary analysis was conducted using data from the IMPACT study, which was a large-scale trial of 465 clinically diagnosed depressed adolescents randomised to receive one of three psychological treatments. Fatigue was measured as a continuous (fatigue severity) and binary variable (fatigue status; fatigued versus non-fatigued) using items from the MFQ and K-SADS. The study explored the prevalence of fatigue, associated clinical and demographic characteristics, changes in fatigue following psychological treatment, and whether fatigue at baseline predicted improvements in depression severity and psychosocial functioning following treatment.
Results: Clinically significant fatigue was reported by 73% of the sample on the MFQ and K-SADS at baseline, although correlations between the two were small, indicating a lack of alignment. Fatigue status and severity on the MFQ and K-SADS were consistently associated with older age and higher depression severity. On the MFQ only, fatigue was also associated with identifying as non-White, reporting more comorbid diagnoses, and experiencing higher psychosocial impairment. However, fatigue severity and status did significantly decrease across all timepoints irrespective of treatment and did not predict improvements in depression severity and psychosocial functioning at 36-weeks. However, up to one third of depressed adolescents reported residual fatigue at 86-weeks follow-up.
Conclusions: Fatigue is a common symptom of adolescent depression that is associated with older age and higher depression severity. Unlike the adult literature, currently available psychological treatments for depression do seem to reduce levels of fatigue in adolescents, and its presence does not seem to impact improvements in depression severity or psychosocial functioning. Despite this, fatigue still seems to be a common residual symptom of adolescent depression, indicating that whilst these treatments may be effective for some, they do not work for everyone.