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78. Altered functional connectivity between frontal cortex and hypothalamic–pituitary–adrenal axis under acute stress in Major Depressive Disorder
Background and methods:
Stress has been critically implicated in the etiology of major depressive disorder (MDD). In an ongoing study, we recruited female participants aged 18-25 years with current MDD (n=17) or remitted MDD (rMDD, n=9), and healthy controls (HC, n=17) to examine potential abnormalities in neural correlates of stress regulation. During a 3T functional magnetic resonance imaging scan, participants were exposed to the Maastricht Acute Stress Test and the Montreal Imaging Stress Task. Imaging data were preprocessed using SPM12, and functional connectivity among 12 a priori regions of interest were analyzed with generalized psychophysical interactions using the CONN toolbox. MDD and rMDD groups were combined for added power.
Results: Relative to HC, the combined MDD/rMDD group was characterized by lower functional connectivity between the hypothalamus and both the orbitofrontal cortex (t(41) = 4.37, p = 0.01) and superior frontal gyrus (t(41) = 4.00, p = 0.02) during the moderate compared to no-stress condition.
Conclusion: Unlike HC, individuals with current or past MDD failed to show increased connectivity post-stress between regulatory regions and the hypothalamus, highlighting a potential neural mechanism for increased stress sensitivity linked to MDD vulnerability. Additional data will be required to corroborate this preliminary conclusion.