Short-term group cognitive behavior therapy contributes to recovery from mild depression: Evidence from functional and structural MRI

• Short-term of group CBT was an effective treatment for mild depression.
• Group CBT increased GMV and decreased ALFF in the right middle frontal gyrus.
• Group CBT decreased the GMV in the left postcentral gyrus.
• Group CBT decreased salience detection for negative stimuli.

We used the functional and structural magnetic resonance imaging to explore the neural correlates of response to group cognitive behavioral therapy (CBT) in mild depression. College students with mild depressive symptoms participated in our 4-week group CBT training. The behavioral results showed that depression symptoms decreased after participation in group CBT. After the training, the gray matter volume (GMV) in the right middle frontal gyrus (MFG) increased and amplitude of low-frequency fluctuations (ALFF) decreased. In addition, GMV in the left postcentral gyrus decreased after the group CBT. Moreover, the increase of percentage change in the right MFG was positively correlated with the decrease of the Beck Depression Inventory (BDI) score, while less decrease in percentage change in the left postcentral gyrus was significantly correlated with greater decrease of BDI score. Finally, after the training, functional connectivity between the right MFG and the insula decreased, while the connectivity between the left postcentral gyrus and the parahippocampal gyrus increased. These findings suggested that short-term participation in group CBT had an effective impact on mild depression. It contributed to decreasing negative bias (salience detection for negative stimuli).