The association between anhedonia and prefrontal cortex activation in patients with major depression: a functional near-infrared spectroscopy study

This study investigated cerebral blood flow characteristics using functional nearinfrared spectroscopy (fNIRS) in agomelatine-treated depressed patients with anhedonia. The level of anhedonia was assessed by the Snaith Hamilton Rating Scale (SHAPS) and Montgomery Åsberg Depression Rating Scale 5-item (MADRS 5-item) score. All 84 patients were evaluated on the day of the study initiation and followed at week 1, 4 and 8 after the study initiation. Graph theory-based network analysis showed 2-back task-modulated global efficiency (adjusted B = 0.055, 95% CI = 0.043 - 0.066) and local efficiency (adjusted B = 0.066, 95% CI = 0.050 - 0.081) were significantly increased 1 week after treatment compared with the baseline. Furthermore, the increased oxy-hemoglobin (oxy-Hb) values from the baseline to the one week after treatment was positively related to the total MADRAS 5-item score reductions in the left-hemispheric orbitofrontal cortex (r = - 0.307, p = 0.005). Our findings suggest that abnormal functional connectivity over OFC may reflect the pathophysiological characteristics of anhedonia and serve as a clinical biomarker for anhedonia.