title: Altered functional connectivity networks of hippocampal subregions in remitted late-onset depression: a longitudinal resting-state study.
abstract: The regional specificity of hippocampal abnormalities in late-life depression (LLD) has been demonstrated in previous studies. In this study, we sought to examine the functional connectivity (FC) patterns of hippocampal subregions in remitted late-onset depression (rLOD), a special subtype of LLD. Fourteen rLOD patients and 18 healthy controls underwent clinical and cognitive evaluations as well as resting-state functional magnetic resonance imaging scans at baseline and at ∼21 months of follow-up. Each hippocampus was divided into three parts, the cornu ammonis (CA), the dentate gyrus, and the subicular complex, and then six seed-based hippocampal subregional networks were established. Longitudinal changes of the six networks over time were directly compared between the rLOD and control groups. From baseline to follow-up, the rLOD group showed a greater decline in connectivity of the left CA to the bilateral posterior cingulate cortex/precuneus (PCC/PCUN), but showed increased connectivity of the right hippocampal subregional networks with the frontal cortex (bilateral medial prefrontal cortex/anterior cingulate cortex and supplementary motor area). Further correlative analyses revealed that the longitudinal changes in FC between the left CA and PCC/PCUN were positively correlated with longitudinal changes in the Symbol Digit Modalities Test (r = 0.624, P = 0.017) and the Digit Span Test (r = 0.545, P = 0.044) scores in the rLOD group. These results may provide insights into the neurobiological mechanism underlying the cognitive dysfunction in rLOD patients.
authors.affiliation: Neurology Department, Affiliated ZhongDa Hospital, Neuropsychiatric Institute and Medical School of Southeast University, Nanjing, 210009, China.
authors.forename: Zan
authors.initials: Z
authors.lastname: Wang
authors.forename: Yonggui
authors.initials: Y
authors.lastname: Yuan
authors.forename: Feng
authors.initials: F
authors.lastname: Bai
authors.forename: Hao
authors.initials: H
authors.lastname: Shu
authors.forename: Jiayong
authors.initials: J
authors.lastname: You
authors.forename: Lingjiang
authors.initials: L
authors.lastname: Li
authors.forename: Zhijun
authors.initials: Z
authors.lastname: Zhang
mesh_terms: D000368:Aged; D001921:Brain / Q000503:physiopathology*; D001931:Brain Mapping; D003865:Major Depressive Disorder / Q000503:physiopathology*; D018450:Disease Progression; D005260:Female; D005500:Follow-Up Studies; D006624:Hippocampus / Q000503:physiopathology*; D006801:Humans; D008137:Longitudinal Studies; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged