Altered regional homogeneity in pediatric bipolar disorder during manic and euthymic state: a resting-state fMRI study.

Pediatric bipolar disorder (PBD) is a severely debilitating illness, which is characterized by episodes of mania and depression separated by periods of remission. Little is known about the abnormalities in PBD in resting state, especially comparing manic with euthymic state. Resting state brain activity measured by fMRI might help to explore neurobiological biomarkers of the disorder. Regional homogeneity (ReHo) was examined with resting-state fMRI on 22 manic PBD patients, 21 euthymic PBD patients and 19 healthy controls. Compared with control group, manic group presented reduced cortical ReHo signal in the superior temporal gyrus(STG), the superior parietal lobe (SPL), precentral gyrus and altered subcortical ReHo signal in the insula and cerebelum crus I. Compared with control group, euthymic group only presented reduced cortical ReHo signal in the STG and SPL. Compared with euthymic group, we found reduced ReHo signal in insula, the STG and increased ReHo signal in cerebelum crus I in the manic group. The neural regions we found to have altered ReHo signal in the PBD manic and euthymic group are parts of the cortical-limbic systems, which are important for affective and cognitive processing. Importantly, our findings suggested that there was a difference between manic and euthymic PBD in the insula, cerebelum crus I and the STG.