Aberrant functional connectivity of the hippocampus in older adults with subthreshold depression

Major depression disorder (MDD) is closely associated with functional and structural changes in the hippocampus (HC). Neuroimaging studies have demonstrated abnormal functional connectivity (FC) of the HC in patients with MDD, but it remains unknown whether this abnormal hippocampal FC pattern occurs in individuals with subthreshold depression (StD) who are at high risk of MDD. Resting-state functional magnetic resonance imaging data were collected from 19 elderly individuals with StD and 18 normal controls. Whole brain voxel-wise FC analyses were conducted to investigate the hippocampal FC pattern by selecting the HC as the region of interest, and correlation analyses were performed to explore the association of altered FC of the HC with self-reported depressive symptoms. The results showed that elderly individuals with StD had substantially decreased FC of the HC to the prefrontal and cuneus cortices compared with healthy normal controls. Moreover, the strength of HC-cuneus connectivity was correlated with self-reported depressive symptoms in elderly individuals with StD. These findings suggest that dysfunctional integration within the HC and cortical regions may occur at an early stage of depression.