Fractional amplitude of low-frequency fluctuations and gray matter volume alterations in patients with bipolar depression

Purpose: We used fractional amplitude of low-frequency fluctuations (fALFF) and gray matter volume (GMV) jointly to explore the mechanism of brain function and structure in unmedicated patients with bipolar disorder (BD). Methods: Thirty first episode drug-naive patients with and thirty healthy controls (HCs) were recruited in this study; All the subjects underwent Magnetic Resonance Imaging (MRI) scanning and performed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS), all the patients with MDD finished the 17-item Hamilton Depression Rating Scale (HAMD17). Data Processing and Analysis for Brain Imaging (DPABI) and SPM8 were used to find potential differences in fALFF and GMV between the two groups. A Pearson correlation model was used to analyze associations of functional and morphometric changes with clinical symptoms and cognitive tests. Results: Compared to healthy controls, the BD group had significantly reduced fALFF values in the lingual gyrus and increased fALFF values in the bilateral superior frontal gyrus and superior frontal gyrus. With regards to VBM, patients with BD showed significant GMV decreases in the bilateral superior temporal gyrus, bilateral superior frontal gyrus, right superior frontal gyrus, right parahippocampal gyrus and precuneus. Additionally, we found an overlap of brain regions focused on the left SFG. Significant negative correlations were observed between abnormal GMV values in the left SFG and vocabulary memory. Conclusion: The superior frontal gyrus was the site of the most robust and reliable abnormality, with an overlap of abnormal structural and functional MRI features that play an important role in pathology in BD.