Regional homogeneity associated with overgeneral autobiographical memory of first-episode treatment-naive patients with major depressive disorder in the orbitofrontal cortex: A resting-state fMRI study

Abstract Background Overgeneral autobiographical memory (OGM) is involved in the onset and maintenance of depression. Recent studies have shown correlations between OGM and alterations of some brain regions by using task-state functional magnetic resonance imaging (fMRI). However, the correlation between OGM and spontaneous brain activity in depression remains unclear. The purpose of this study was to determine whether patients with major depressive disorder (MDD) show abnormal regional homogeneity (ReHo) and, if so, whether the brain areas with abnormal ReHo are associated with OGM. Methods Twenty five patients with MDD and 25 age-matched, sex-matched, and education-matched healthy controls underwent resting-state fMRI. All participants were also assessed by 17-item Hamilton Depression Rating Scale and autobiographical memory test. The ReHo method was used to analyze regional synchronization of spontaneous neuronal activity. Results Patients with MDD, compared to healthy controls, exhibited extensive ReHo abnormalities in some brain regions, including the frontal, temporal, and occipital cortex. Moreover, ReHo value of the orbitofrontal cortex was negatively correlated with OGM scores in patients with MDD. Limitations The sample size of this study was relatively small, and the influence of physiological noise was not completely excluded. Conclusions These results suggest that abnormal ReHo of spontaneous brain activity in the orbitofrontal cortex may be involved in the pathophysiology of OGM in patients with MDD.