Alterations of regional homogeneity in pediatric bipolar depression : 1 A resting - state fMRI study

17 18 Objective: Pediatric bipolar disorder (PBD) has attracted increasing attentions due to its high 19 prevalence and great influence on social functions of children and adolescents. However, the 20 pathophysiology underlying PBD remains unclear. In the present study, the resting-state 21 functional magnetic resonance imaging (fMRI) was used to detect abnormalities of baseline brain 22 functions in depressed PBD youth. 23 Methods: Seventeen youth with PBD-depression aged 10-18 years old and 18 age-and 24 sex-matched normal controls were recruited in this study. The fMRI data under resting state were 25 obtained on a Siemens 3.0 Tesla scanner and were analyzed using the regional homogeneity 26 (ReHo) method. Correlations between the ReHo values of each survived area and the severity of 27 depression symptoms in patients were further analyzed. 28 Results: As compared with the control group, PBD-depression patients showed decreased ReHo 29 in the medial frontal gyrus, bilateral middle frontal gyrus and middle temporal gyrus, and the right 30 putamen. Significant negative correlations of the mood and feelings questionnaire scores with 31 mean ReHo values in the medial frontal gyrus and the right middle frontal gyrus in 32 PBD-depression patients were observed. 33 Conclusion: Our results suggest that extensive regions with altered baseline brain activities are 34 existed in PBD-depression and these brain regions mainly locate in the fronto-limbic circuit and 35 associated striatal structures. Moreover, the present findings also add to our understanding that 36 there could be unique neuropathophysiological mechanisms underlying PBD-depression. 37 38 3 39