Amplitude of brain low-frequency fluctuation and functional connectivity changes based on fMRI study in first-episode...

Recent functional connectivity (FC) studies have proved the potential value of resting-state functional magnetic resonance imaging (rs-fMRI) in the study of major depressive disorder (MDD). This study investigates alterations of amplitude of low-frequency fluctuations (ALFF) in first-episode major depressive disorder (FED) using rs-fMRI, and then explore the abnormalities of FC.

A total of 66 FED patients and 66 healthy controls were recruited for this study. The amplitude of low frequency fluctuations (ALFF) method was employed to assess changes in brain activity across the entire brain in both groups. Subsequently, the identified brain regions were used as seeds to examine whole-brain functional connectivity (FC) changes. Additionally, we conducted partial correlation analyses to investigate the relationship between functional connectivity values in FED patients and clinical variables, such as the 17-item Hamilton Depression Rating Scale (HAMD-17) scores and illness duration.

FED patients exhibited increased ALFF values in the right fusiform and the right parahippocampal gyrus compared to controls (P < 0.05, GRF correction). Enhanced FC was observed between the right parahippocampal gyrus and the right precentral gyrus, with reduced connectivity to the brainstem (P < 0.05, GRF correction). The FC values of the right parahippocampal gyrus and right precentral gyrus positively correlated with the HAMD-17 scores (r = 0.314, P = 0.012).

Abnormal ALFF and FC in several brain regions of FED patients suggest these areas could serve as biological markers for identifying FED.