In a recent study published in BMC Psychiatry, researchers sought to investigate volumetric alterations of individual brainstem regions with regard to the number of previous MDD episodes and disease duration.

The authors indicated that there are a sparse number of neuroimaging studies examining morphological changes of the brainstem in patients with first-episode MDD (FMDD) and recurrent MDD (RMDD).

The authors wrote, “Based on previous findings, we hypothesized that morphologic changes of the brainstem could be involved in the pathophysiology of MDD, and depressive recurrence might lead to distinctive deficits of brainstem substructures in MDD patients.”

The authors indicated that the study intended to examine volume changes in each region of the brainstem in patients with first-episode and recurrent MDD and particularly to assess the effect of recurrence on brainstem volume in MDD patients.

The study included 111 individuals, of whom 36 were diagnosed with FMDD, 25 individuals with RMDD, and 50 healthy controls (HCs) who underwent T1-weighted structural MRI scans. Researchers employed a Bayesian segmentation algorithm to examine the volume of each brainstem region, including the medulla oblongata, pons, midbrain, and superior cerebellar peduncle (SCP), as well as the whole brainstem volume.

To acquire brain regions with significant variances among three groups, analyses of variance (ANOVA) were performed, and post hoc tests were then calculated for intergroup comparisons. Partial correlation analyses were further conducted to detect correlations between regional volumes and clinical features.

The results from the ANOVA indicated that among the three groups, there were significant brainstem volumetric variances in the pons, midbrain, SCP, and the whole brainstem (F = 3.996~5.886, adjusted P = .015~.028). Both groups of MDD patients displayed diminished volumes in the pons as well as the entire brainstem (P = .002~.034) compared with the healthy controls; however, only the FMDD group demonstrated a meaningfully decreased volume in the midbrain (P = .003). Specifically, the RMDD group showed significantly reduced SCP volume when compared with both the FMDD (P = .021) group and HCs (P = .008). The authors also noted that the correlation analyses revealed that the SCP volumes were negatively correlated with the number of depressive episodes (r = –0.36, P <.01) and illness duration (r = –0.28, P = .035) in patients with MDD.

The authors wrote, “The current study is in parallel with previous research findings which showed significant structural alterations in the brainstem regions in MDD patients compared to HCs.”

Based on their findings, the authors concluded, “The present findings provided evidence of decreased brainstem volume involving in the pathophysiology of MDD, particularly, volumetric reduction in the SCP might represent a neurobiological marker for RMDD. Further research is needed to confirm our observations and deepen our understanding of the neural mechanisms underlying depression recurrence.”

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