Comorbid posttraumatic stress disorder and major depressive disorder: The usefulness of a sequential treatment approach within a randomised design.

Cognitive Processing Therapy (CPT) and Behavioural Activation Therapy (BA) were used to treat individuals with comorbid posttraumatic stress disorder (PTSD) and major depressive disorder (MDD). Fifty-two individuals (48 women, 4 men) were randomized to CPT alone (n = 18), CPT then BA for MDD (n = 17), or BA then CPT (n = 17). Presenting trauma was primarily interpersonal (87 %). Participants were assessed at pre-, posttreatment, and 6-month follow-up. PTSD and MDD symptoms were the main outcome of interest; trauma cognitions, rumination, and emotional numbing were secondary outcomes. All groups showed sizeable reductions in PTSD and depression (effect sizes at follow-up ranging between 1.02-2.54). A pattern of findings indicated CPT/BA showed better outcomes in terms of larger effect sizes and loss of diagnoses relative to CPT alone and BA/CPT. At follow-up greater numbers of the CPT/BA group were estimated to have achieved good end-state for remission of both PTSD and depression (49 %, CI [.26, .73]) relative to CPT alone (18 %, CI [.03, .38]) and BA/CPT (11 %, CI [.01, .29]). Although tempered by the modest sample size, the findings suggest that individuals with comorbid PTSD and MDD may benefit from having PTSD targeted first before remaining MDD symptoms are addressed.