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Major depressive disorder (MDD) is a common debilitating disorder characterized by impaired spontaneous brain activity, yet little is known about its alterations in dynamic properties and the molecular mechanisms associated with these changes.
Based on the resting-state functional MRI data of 65 first-episode, treatment-naïve patients with MDD and 66 healthy controls, we compared dynamic regional homogeneity (dReHo) of spontaneous brain activity between the two groups, and we investigated gene expression profiles associated with dReHo alterations in MDD by leveraging transcriptional data from the Allen Human Brain Atlas and weighted gene co-expression network analysis.
Compared with healthy controls, patients with MDD consistently showed reduced dReHo in both fusiform gyri and in the right temporal pole and hippocampus. The expression profiles of 16 gene modules were correlated with dReHo alterations in MDD. These gene modules were enriched for various biological process terms, including immune, synaptic signalling, ion channels, mitochondrial function and protein metabolism, and were preferentially expressed in different cell types.
Patients with MDD have reduced dReHo in brain areas associated with emotional and cognitive regulation, and these changes may be related to complex polygenetic and polypathway mechanisms.
Genome-wide association studies (GWAS) have consistently revealed that a variant of microRNA 137 (MIR137) shows a quite significant association with schizophrenia. Identifying the network of genes regulated by MIR137 could provide insights into the biological processes underlying schizophrenia. In addition, DLPFC functional connectivity, a robust correlate of MIR137, may provide plausible endophenotypes. However, the regulatory role of the MIR137 gene network in the disrupted functional connectivity remains unclear. Here, we tested the effects of the MIR137 regulated genes on the risk for schizophrenia and DLPFC functional connectivity.
To evaluate the additive effects of the MIR137 regulated genes (N = 1274), we calculated a MIR137 polygenic risk score (PRS) for schizophrenia and tested its association with the risk for schizophrenia in the genomic data of a Han Chinese population that included schizophrenia patients (N = 589) and normal controls (N = 575). We then investigated the association between MIR137 PRS and DLPFC functional connectivity in two independent young healthy cohorts (N = 356 and N = 314).
We found that the MIR137 PRS successfully captured the differences in genetic structure between the patients and controls, but the single gene MIR137 did not. We then consistently found that a higher MIR137 PRS was correlated with lower functional connectivities between the DLPFC and both the superior parietal cortex and the inferior temporal cortex in two independent cohorts.
The findings suggested that these two functional connectivities of the DLPFC could be important endophenotypes linking the MIR137-regulated genetic structure to schizophrenia.
Auditory verbal hallucinations (AVHs) have been associated with deficits
in auditory and speech-related networks. However, the resting-state
cerebral blood flow (CBF) alterations specific to AVHs in schizophrenia
To explore AVH-related CBF alterations in individuals with
In total, 35 individuals with schizophrenia with AVHs, 41 individuals
with schizophrenia without AVHs and 50 controls underwent arterial spin
labelling magnetic resonance imaging. The CBF differences were voxel-wise
compared across the three groups.
We found AVH-specific CBF increase in the right superior temporal gyrus
and caudate, and AVH-specific CBF decrease in the bilateral occipital and
left parietal cortices. We also observed consistent CBF changes in both
schizophrenia subgroups (i.e. those with and without AVHs) including
decreased CBF in the bilateral occipital regions, the left lateral
prefrontal and insular cortices, and the right anterior cingulate cortex
and increased CBF in the bilateral lateral temporal regions and putamen,
the left middle cingulate cortex and the right thalamus.
The AVH-specific CBF increases in the auditory and striatal areas and CBF
reductions in the visual and parietal areas suggest that there exists a
CBF redistribution associated with AVHs.
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