Abstract
BackgroundMajor depressive disorder (MDD) has been associated with abnormal structure and function of the brain's affective network, including the amygdala and orbitofrontal cortex (OFC). However, it is unclear if alterations of resting-state function in this affective network are present at the initial onset of MDD.AimsTo examine resting-state function of the brain's affective network in first-episode, medication-naive patients with MDD compared to healthy controls (HCs).MethodsResting-state functional magnetic resonance imaging (rs-fMRI) was performed on 32 first-episode, medication-naive young adult patients with MDD and 35 matched HCs. The amplitude of low-frequency fluctuations (ALFF) of the blood oxygen level-dependent (BOLD) signal and amygdala-seeded functional connectivity (FC) were investigated.ResultsCompared to HC, MDD patients showed reduced ALFF in the bilateral OFC and increased ALFF in the bilateral temporal lobe extending to the insular and left fusiform cortices. Enhanced anti-correlation of activity between the left amygdala seed and the left OFC was found in MDD patients but not in HCs.ConclusionsReduced ALFF in the OFC suggests hypo-functioning of emotion regulation in the affective network. Enhanced anti-correlation of activity between the amygdala and OFC may reflect dysfunction of the amygdala-OFC network and additionally represent a pathological process of MDD.
Highlights
Major depressive disorder (MDD) is a common psychiatric disorder, typically characterized by pervasive despondency and failure to suppress negative thought, as well as specific cognitive and behavioral alterations [1]
Reduced amplitude of low-frequency fluctuations (ALFF) in the orbitofrontal cortex (OFC) suggests hypo-functioning of emotion regulation in the affective network
Altered ALFF in patients with MDD In support of our hypothesis, patients with MDD showed significantly decreased ALFF bilaterally in the OFC compared to healthy controls (HCs) (Figure 1 and Table 2)
Summary
Major depressive disorder (MDD) is a common psychiatric disorder, typically characterized by pervasive despondency and failure to suppress negative thought, as well as specific cognitive and behavioral alterations [1]. Previous neuroimaging studies have revealed abnormal structure and function of the OFC and amygdala in patients with MDD. Hyperactivity in the amygdala has been inversely associated with OFC reactivity during the suppression of negative emotions [23], and abnormal amygdala-OFC functional connectivity has been observed in depressed patients [24,25]. Major depressive disorder (MDD) has been associated with abnormal structure and function of the brain’s affective network, including the amygdala and orbitofrontal cortex (OFC).
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