Neural activity in adults with major depressive disorder differs from that in healthy individuals: A resting-state functional magnetic resonance imaging study

Abstract

ObjectiveCurrently, findings regarding resting-state functional magnetic resonance imaging studies of major depressive disorder (MDD) are inconsistent. In contrast to the previously used a priori seed-based functional connectivity analyses, this study employed whole-brain exploratory analyses and aimed to explore neural activity patterns in Chinese adults with MDD.Materials and methodsSpecifically, this study examined the amplitude of low-frequency fluctuations within the whole brain and adopted a large-scale brain network template to explore the core dysfunctional brain regions in individuals with MDD.ResultsOverall, 32 individuals with MDD and 32 healthy controls were evaluated. Compared to healthy controls, individuals with MDD showed more profound alterations in the amplitude of low-frequency fluctuations in the temporolimbic affective circuit (e.g., middle temporal gyrus and parahippocampus) and default mode network (e.g., precuneus and thalamus). Moreover, functional connectivity between the left mid-insula and parietal regions within the sensorimotor network was weaker in individuals with MDD than in healthy controls.ConclusionIn conclusion, the neural characteristics of MDD correspond to cognitive deficits in self-referential processing and emotional processing and are related to a risk of sensory disorders or psychomotor retardation. These findings present neural markers that may be used to identify MDD, contributing to clinical diagnosis.

Effects of repetitive transcranial magnetic stimulation on individual variability of resting-state functional connectivity in major depressive disorder

“…This study examined individual variability of rs-fc from regions belonging to functional networks implicated in MDD, in the context of rTMS treatment interventions. In contrast to a prior study showing greater variability of network connectivity in MDD, 36 we did not find increased variability in MDD at baseline. While some results did not survive statistical correction, consistent patterns emerged with regard to the right sgACC: patients with MDD showed (nonsignificant) lower variability at baseline, rTMS increased variability toward that observed in healthy controls, and lower baseline variability was somewhat related to greater symptom reductions.…”

“…[29][30][31][32]34,35 We assessed group differences in MCD between patients with MDD and healthy controls at baseline. Given recent work showing greater individual variability of rs-fc across the brain in patients with MDD, 36 and our work showing greater MCD in those with autism, schizophrenia, and bipolar disorder, 17,18,22 we hypothesize that patients with MDD would show greater MCD than healthy controls. Second, individual variability was investigated as a potential biomarker of response in patients with MDD; we hypothesized that rTMS would reduce individual variability and that this reduction would be associated with clinical improvement.…”

“…Our analytic approach calculated functional connectivity using a seed-based approach compared with the whole-brain connectivity approach, 5 – 7 which may have been too constrained for detecting other connectivity patterns beyond the selected ROIs. 36 …”

“…Our analytic approach calculated functional connectivity using a seed-based approach compared with the whole-brain connectivity approach, [5][6][7] which may have been too constrained for detecting other connectivity patterns beyond the selected ROIs. 36 Prior studies have reported inconsistent findings of connectivity in MDD using case-control group-level differences; 26,45,46 group-averaging analytical approaches may be inadequate to preserve the substantial heterogeneity in symptoms and connectivity in MDD. 5 Individual variability metrics such as MCD provide a unique way of analyzing brain functions of a specific system while allowing for unique differences in patients' individual connectivity profiles, which may drive greater variability (i.e., MCD does not assume every patient shows the same pattern of deficits in sgACC connectivity to other brain regions).…”