Brain functional network correlates and predictors of the perioperative antidepressant effect of esketamine in breast cancer patients: a double-blind randomized controlled trial using resting-state fMRI and graph theory.

Postoperative depression adversely influences breast cancer patients' clinical outcomes. Our prior study demonstrated that intraoperative esketamine ameliorated postoperative depression in breast cancer patients, yet the underlying neural mechanism remains incompletely understood. We performed a double-blind randomized controlled trial in 35 breast cancer patients with preoperative depressive symptoms, who were randomly given intraoperative esketamine 0.25 mg·kg⁻¹ (n = 18) or saline placebo (n = 17) over the initial 40 min of anesthesia. Resting-state functional magnetic resonance imaging data were collected at preoperative baseline and postoperative day 1 follow-up to calculate brain functional network measures. In contrast to no significant change in the placebo group, the esketamine group showed increased degree centrality of the left inferior frontal gyrus, opercular part from baseline to follow-up, which was related to improvement in depressive symptoms. Additionally, we found significant associations of baseline network measures at the global, nodal, and edge levels with short-term and long-term improvements in depressive symptoms following esketamine administration. These findings may not only provide novel insights into the neural mechanism by which esketamine exerts its antidepressant efficacy during the perioperative period, but also highlight the prospect of functional network measures as useful predictors of antidepressant response to esketamine in patients with breast cancer.