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Background: Previous studies have demonstrated structural and functional changes of the hippocampus in patients with major depressive disorder (MDD). However, no studies have analyzed the dynamic functional connectivity (dFC) of hippocampal subregions in melancholic MDD. We aimed to reveal the patterns for dFC variability in hippocampus subregions – including the bilateral rostral and caudal areas and its associations with cognitive impairment in melancholic MDD. Methods: Forty-two treatment-naive MDD patients with melancholic features and 55 demographically matched healthy controls were included. The sliding-window analysis was used to evaluate whole-brain dFC for each hippocampal subregions seed. We assessed between-group differences in the dFC variability values of each hippocampal subregion in the whole brain and cognitive performance on the MATRICS Consensus Cognitive Battery (MCCB). Finally, association analysis was conducted to investigate their relationships. Results: Patients with melancholic MDD showed decreased dFC variability between the left rostral hippocampus and left anterior lobe of cerebellum compared with healthy controls (voxel p < 0.005, cluster p < 0.0125, GRF corrected), and poorer cognitive scores in working memory, verbal learning, visual learning, and social cognition (all p < 0.05). Association analysis showed that working memory was positively correlated with the dFC variability values of the left rostral hippocampus-left anterior lobe of the cerebellum (r = 0.338, p = 0.029) in melancholic MDD. Conclusions: These findings confirmed the distinct dynamic functional pathway of hippocampal subregions in patients with melancholic MDD, and suggested that the dysfunction of hippocampus-cerebellum connectivity may be underlying the neural substrate of working memory impairment in melancholic MDD. [ABSTRACT FROM AUTHOR]

Background: H protons magnetic resonance spectroscopy (1H-MRS) has been used to detect the biochemical metabolism changes and the mechanism of executive dysfunction in major depressive disorder (MDD). While, finding information associated with non-suicidal self-injury (NSSI) among adolescents with MDD is challenging. The present study aimed to examine the executive function and biochemical metabolism alterations, as well as to elucidate their associations in depressed adolescents with NSSI.Methods: A total of 86 adolescents with MDD (40 with NSSI, and 46 without NSSI) and 28 healthy controls were recruited in the current study. The executive function was assessed by Digital symbol test (DST), Wisconsin Card Sorting Test (WCST), Trail Making Test, part B (TMT-B), and Verbal fluency (VF). Bilateral metabolite levels of the prefrontal cortex (PFC), anterior cingulated cortex (ACC), lenticular nucleus (LN) of basal ganglia and thalamus were obtained by 1H-MRS at 3.0 T, and then the ratios of N-acetyl aspartate (NAA) and choline-containing compounds (Cho) to creatine (Cr) were determined, respectively. Finally, association analysis was conducted to investigate their relationships.Results: The depressed adolescents with NSSI showed significantly lower VF scores than those without NSSI and healthy controls. We also found significantly higher NAA/Cr ratios in the right thalamus, while significantly lower Cho/Cr ratios in the right thalamus of NSSI group than the MDD without NSSI group and healthy controls. And NSSI group also showed lower NAA/Cr ratio in the right LN than the MDD without NSSI group. For MDD with NSSI, the NAA/Cr ratios of the left thalamus were positively correlated with the time of TMTB and the Cho/Cr ratios of the left ACC were positively correlated with the VF scores.Conclusions: Depressed adolescents with NSSI may have executive dysfunction and NAA and Cho metabolism abnormalities in the thalamus. And the NAA/Cr ratios of the right LN could distinguish NSSI from depressed adolescents. Further, the executive dysfunction may be associated with the abnormal NAA metabolism in the left thalamus and ACC. [ABSTRACT FROM AUTHOR]