1 1 Double trouble: Do symptom severity and duration interact to predicting treatment outcomes in 2 adolescent depression? 3Lorenzo Lorenzo-Luaces*, PhD a 4Natalie Rodriguez-Quintana, BA, MPHa 5Allen J. Bailey, BA a 6 7a Department of Psychological and Brain Sciences, Indiana University – Bloomington, Indiana 8* Corresponding Author: Lorenzo Lorenzo-Luaces: 1101 E 10th St, Bloomington, IN 47405,
[email protected] 10Word count: 3315 11 12© 2020. This manuscript version is made available under the CC-BY-NC-ND 4.0 13Article accepted at Behavioural Research and Therapy (BRAT), please cite as: 14 15Lorenzo-Luaces, L., Rodriguez-Quintana, N., & Bailey, A. J. (2020). Double trouble: Do 16depression severity and duration interact to predicting treatment outcomes in adolescent 17depression? Behaviour Research and Therapy. Advanced online publication. 18 2 19 Abstract 20Studies suggest that depression severity and duration interact to predict outcomes in depression 21treatment. To our knowledge, no study has explored this question in a sample with a placebo 22control, two therapies, and their combination nor with adolescents. We used data from the 23Treatment of Adolescent Depression Study (N=439), in which adolescent were randomized to 24placebo (PBO), cognitive-behavioral therapy (CBT), antidepressants medications (MEDs), or 25their combination (COMB). We explore the interaction between depression severity, chronicity, 26and treatments (vs. placebo) in predicting outcomes. There was interaction between severity and 27chronicity when comparing COMB and CBT with PBO, but not MEDs. In non-chronic 28depression, the effects of CBT were inversely related to severity to the point that CBT appeared 29iatrogenic with more severe depression. In chronic depression, the effects of CBT did not vary 30by severity, but the relative effects of COMB grew, being smallest in milder, more dysthymic- 31like depression, and largest in chronic-severe depression.