Brain functional effects of cognitive behavioral therapy for depression: A systematic review of task-based fMRI studies.

Background: Depressive disorders are associated with alterations in brain function, affecting processes such as affective and reward processing and emotion regulation. However, the influence of Cognitive Behavioral Therapy (CBT) on the neuronal patterns remains inadequately understood. Therefore, this review systematically summarizes longitudinal fMRI brain activity changes in depressive patients treated with CBT and their association with symptom remission.

Methods: This systematic review was conducted according to the PRISMA statement. Out of 2149 results of the literature search, N = 14 studies met the inclusion criteria (e.g., diagnosis of a current depressive disorder, assessment of longitudinal task-based fMRI, and the analysis of functional changes before and after CBT).

Results: The findings reveal (1) diminished limbic reactivity following CBT across various tasks, (2) increased striatal activity during reward processing, but decreased activity during affective processing and future thinking, and (3) alterations in cingulate and prefrontal cortex activity across tasks. Partially, these results are associated with symptom remission, especially in the subgenual anterior cingulate cortex.

Limitations: There are heterogenous results especially in cortical areas that might partially be due to methodological issues like differences across the studies in terms of task content, statistical evaluation, and interventions. Thus, future research should focus on the standardization of methodologies.

Conclusions: The results indicate that CBT partially normalizes the neural patterns of depressive patients, particularly within regions involved in affective and reward processing and the development of negative cognitive biases. Overall, potential neural mechanisms underlying CBT were identified, underscoring its effectiveness on an objective neurobiological basis.