Altered effective connectivity during cognitive distancing in cognitive behavioral therapy nonresponders with depression

Approximately half of individuals with major depressive disorder (MDD) do not respond to cognitive behavioral therapy (CBT). Cognitive distancing is a reappraisal tactic central to CBT, and neural responses during reappraisal have been linked to psychotherapy outcome. We examined whether pretreatment effective connectivity during cognitive distancing was associated with CBT response in adults with MDD.

Seventy-seven outpatients with MDD (31 women) completed fMRI during a distancing task before 25 CBT sessions as part of the SPeED trial, which included a pre-CBT phase of exercise or waiting list. Dynamic causal modeling estimated effective connectivity within a 10-region network. Group differences were assessed with parametric empirical Bayes, and predictive utility was evaluated with leave-one-out cross-validation.

Responders (n = 39) showed greater relative modulation along a dorsomedial-to-ventrolateral prefrontal-to-superior frontal/pre-supplementary motor area cascade during distancing, whereas nonresponders exhibited greater relative modulation of amygdala-to-ventrolateral prefrontal cortex connectivity. Nonresponders showed decreased dorsolateral prefrontal self-inhibition during negative picture processing, consistent with heightened local excitability. Distancing-related effects exceeded 99% posterior probability and predicted treatment response in cross-validation (r = .21-.31, p < .05).

Effective connectivity during distancing robustly differentiated responders from nonresponders, with nonresponders showing weaker intra-prefrontal control and stronger amygdala-to-prefrontal influence. These neural patterns contribute to insight into CBT nonresponse and suggest a mechanism associated with lowered symptom improvement through cognitive interventions. However, incremental predictive value beyond baseline clinical measures was modest. If replicated prospectively, such measures may contribute to multimodal prediction models and adjunctive treatment strategies.

Neurobiological correlates and mechanisms of the augmentation of psychotherapy with endurance exercise in mild to moderate depression - SPeED, http://apps.who.int/trialsearch/Trial2.aspx?TrialID=DRKS00008869, DRKS00008869.