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This page is an AI-assisted Turkish summary of the study presented at the 26th World Congress of Psychiatry. The study belongs to the presenting authors; please refer to the original source when citing it.

EV0823

Changes in local neural activity and functional connectivity density in first-episode and recurrent major depressive disorder: a resting-state fMRI study

ALTERATIONS IN LOCAL NEURAL ACTIVITY AND FUNCTIONAL CONNECTIVITY DENSITY IN FIRST-EPISODE AND RECURRENT MAJOR DEPRESSIVE DISORDER: A RESTING-STATE FMRI STUDY

Increased functional connectivity density in the left anterior cingulate cortex was identified as a distinguishing feature of recurrent major depressive disorder compared with first-episode patients and healthy controls.

The study aimed to elucidate the mechanisms of recurrence and progression by comparing differences in intrinsic brain activity between recurrent major depressive disorder (RMDD) and first-episode major depressive disorder (FMDD). A total of 99 participants were examined: 33 with FMDD, 20 with RMDD, and 46 healthy controls (HC). All participants underwent resting-state functional magnetic resonance imaging; the data were preprocessed using DPABI to calculate four-dimensional spatial-temporal consistency of local neural activity (FOCA) and functional connectivity density (FCD) measures. Between-group differences were assessed using analysis of covariance (ANCOVA), with age, sex, and mean framewise displacement as covariates, followed by region-of-interest extraction and correlation analyses with clinical measures. Compared with controls, both the FMDD and RMDD groups showed reduced FOCA in the left superior parietal gyrus; the RMDD group also showed significantly increased FOCA in the right inferior frontal gyrus, both global and local FCD in the left anterior cingulate cortex (ACC), and local FCD in the right parahippocampal gyrus compared with both the FMDD and HC groups. Aberrant FCD values in the left ACC were positively correlated with the number of episodes and Snaith-Hamilton Pleasure Scale (SHAPS) scores: global FCD and number of episodes, r = 0.584, p = 0.011; local FCD and number of episodes, r = 0.691, p = 0.002; global FCD and SHAPS, r = 0.692, p = 0.001; local FCD and SHAPS, r = 0.708, p = 0.001. All clusters survived AlphaSim correction (p < 0.01, cluster size > 23 voxels). The authors interpreted the findings as distinct functional alterations in FMDD and RMDD and suggested that increased functional connectivity in the left ACC may be a core feature of functional dysregulation in RMDD.

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