Functional connectivity of suprachiasmatic nucleus in major depressive episodes patients with morning heavy night light rhythm

Abstract

Objective To explore the variations of functional connectivity in depressive episode patients with diurnal rhythm. Methods Totaly 44 patients with depressive episode with diurnal rhythm(rhythm group), 58 patients with depressive episode without diurnal rhythm(non-rhythm group) and 56 matched healthy volunteer controls(healthy group)were scanned with 3.0 T MRI Scanner.Functional connectivity (FC) were calculated between suprachiasmatic nucleus(SCN) and whole brain regions.According to results of ANOVA, group-wise two sample t-test was completed.Correlation analysis were conducted between FC of significant difference brain regions and the score of Hamilton rating scale(HAMD-24) for depression. Results The brain regions showing differences among three groups were located in the left medial superior frontal gyrus(MNI: x=0, y=39, z=51; K=14) and right cerebellum crus 1(MNI: x=39, y=-48, z=-36; K=18)(P<0.05, Alphasim). Compared with non-rhythm group, the FC of rhythm group showed significantly increased in the left medial superior frontal gyrus and right triangular inferior frontal gyrus(MNI: x=39, y=27, z=27; K=10)(P<0.05, Alphasim). Compared with healthy group, the FC of non-rhythm group showed significantly decreased in left medial superior frontal gyrus(P<0.05, Alphasim). Positive correlation was found between FC in left medial superior frontal gyrus and despair score of HAMD-24(r=0.31, P=0.041). Conclusion The synergistic increase in SCN and prefrontal activity in patients with depressive episodes with morning heavy night light rhythm which may be involved in the formation mechanism of the diurnal rhythm. Key words: Depressive episode; Diurnal rhythm; Functional magnetic resonance; Suprachiasmatic nucleus; Functional connectivity