Brain structural and functional aberrant of hippocampal subregions was associated with somatic depression.

Background: Somatic depression (SD) was a different subtype compared to non- somatic depression (NSD) in presentation of the resting-state MRI study. Among these studies, hippocampus was believed to be significantly associated with somatization symptoms. However, the hippocampus was a heterogeneous structure which contains five main subfields. Until now, the disruption pattern of the hippocampus subfields in SD patients were not clearly. Therefore, it is necessary to study the different function of each hippocampus subfield in SD group.

Methods: 261 subjects were recruited including 190 major depressive disorder (MDD) patients and 71 health controls (HC). All subjects underwent 3.0T resting state magnetic resonance image scanning. The disruption of grey matter volume (GMV) and the functional connectivity (FC) of the hippocampal subregion were compared between each pairs, respectively. In addition, the correlation between the abnormal functional connectivity of the hippocampal subregions and the symptom of the SD patients were estimated.

Results: Compared to the NSD group, SD group showed decreased grey matter volume (GMV) in the left hippocampus amygdala transition area (HATA) and right HATA. Relative to the NSD group, the SD group showed decreased FC between the left HATA and the left superior occipital gyrus, between the right HATA and left middle temporal gyrus. In SD group, the FC between the left HATA and left superior occipital gyrus were positively correlated with the HAMD-17 and cognitive disturbance.

Conclusion: The structural and functional aberrant of HATA was a neurobiology indicator of the SD and the left superior occipital gyrus may be a potential neuroregulatory targets for SD.