Depressive symptoms at age 9-13 and chronic disabling fatigue at age 16: a longitudinal study, by Simon M Collin, Tom Norris, Carol Joinson, Maria E Loades, Glyn Lewis, Stephen A Stansfeld, Esther Crawley in  Journal of Adolescence Vol 75, pp 123-129, August 2, 2019 [https://doi.org/10.1016/j.adolescence.2019.07.014]

Research abstract:

Introduction
We investigated whether depressive symptoms at ages 9-13 years were associated with chronic disabling fatigue (CDF) at age 16 among children in the Avon Longitudinal Study of Parents & Children (ALSPAC) birth cohort.

Methods
Depressive symptoms at ages 9, 10, 11, 12, and 13 years were defined as a child- or parent-completed Short Mood and Feelings Questionnaire (SMFQ) score ≥11 (range 0-26). SMFQ score was also analysed as a continuous exposure. Chronic disabling fatigue at 16 was defined as fatigue of ≥6 months’ but <5 years’ duration which prevented school attendance or activities, for which other causes were not identified, and with a Chalder Fatigue Questionnaire score ≥19. Logistic regression was used with multiple imputation to correct for missing data bias. We performed sensitivity analyses in which children who had CDF and depressive symptoms at age 16 were reclassified as not having CDF.

Results
In fully adjusted models using imputed data (N = 13,978), depressive symptoms at ages 9, 11, and 13 years were associated with 2- to 3-fold higher odds of CDF at age 16. Each one-point increase in SMFQ score at ages 9, 10, 11, 12, and 13 years was associated with 6-11% higher odds of CDF at age 16. Depressive symptoms and continuous SMFQ scores at each age were not associated with CDF if the outcome was reclassified to exclude children with comorbid depressive symptoms at age 16.

Conclusions
Depressive symptoms at ages 9-13 were associated with chronic disabling fatigue at age 16, but causality is not certain.