Neural correlates of thought-action fusion and their associations with rumination in patients with major depressive disorder.

Thought-action fusion (TAF) is the metacognitive belief that the power of thoughts can have real-life consequences, often inducing unpleasant inner experiences and recruiting coping strategies such as rumination. Therefore, this study aimed to investigate the neural correlates of TAF and their associations with rumination in depression. A total of 37 patients with major depressive disorder (MDD) and 37 healthy controls (HCs) underwent functional magnetic resonance imaging with a TAF induction task and psychological assessments. In the TAF induction task, participants were asked to read the name of a close person (CP) or neutral person (NP) in association with negative (Neg) TAF and neutral (Neu) control statements. In this study, our TAF induction task activated brain regions, including the salient and default-mode networks, in the MDD and HC groups. However, along with higher likelihood TAF and rumination, behavioral data showed less negative feelings and longer reaction times under the NegCP condition in the MDD group compared with the HC group. Furthermore, in the MDD group, significantly higher activation in the bilateral caudate nuclei, left inferior frontal gyrus/anterior insula, putamen, and inferior parietal lobule under the NegCP condition was positively correlated with TAF and reflection. These findings suggest that during the TAF task, patients with MDD may activate different brain areas associated with the maintenance of high stimulus saliency and habit formation, which are important neural correlates linking TAF and rumination in depression.