Shared and Distinct Fractional Amplitude of Low-Frequency Fluctuation Patterns in Major Depressive Disorders With and Without Gastrointestinal Symptoms

Abstract

Objective: Gastrointestinal (GI) symptoms are fairly common somatic symptoms in depressed patients. The purpose of this study was to explore the influence of concomitant GI symptoms on the fractional amplitude of low-frequency fluctuation (fALFF) patterns in patients with major depressive disorder (MDD) and investigate the connection between aberrant fALFF and clinical characteristics. Methods: This study included 35 MDD patients with GI symptoms (GI-MDD patients), 17 MDD patients without GI symptoms (nGI-MDD patients), and 28 healthy controls (HCs). The fALFF method was used to analyze the resting-state functional magnetic resonance imaging data. Correlation analysis and pattern classification were employed to investigate the relationship of the fALFF patterns with the clinical characteristics of patients. Results: GI-MDD patients exhibited higher scores in the HRSD-17 and suffered more severe insomnia, anxiety/somatization, and weight loss than nGI-MDD patients. GI-MDD patients showed higher fALFF in the right superior frontal gyrus (SFG)/middle frontal gyrus (MFG) and lower fALFF in the left superior medial prefrontal cortex (MPFC) compared with nGI-MDD patients. A combination of the fALFF values of these two clusters could be applied to discriminate GI-MDD patients from nGI-MDD patients, with accuracy, sensitivity, and specificity of 86.54, 94.29, and 70.59%, respectively. Conclusion: GI-MDD patients showed more severe depressive symptoms. Increased fALFF in the right SFG/MFG and decreased fALFF in the left superior MPFC might be distinctive neurobiological features of MDD patients with GI symptoms.

Keywords: fractional amplitude low-frequency fluctuation; functional magnet resonance imaging (fMRI); gastrointestinal symptoms; major depressive disorder; somatic symptoms.

Figure 1

Brain regions showing significantly different fALFF values across three groups at a false discovery rate (FDR)-corrected p < 0.05. The color bar indicates the F values based on ANCOVA. fALFF, fractional amplitude of low-frequency fluctuation; ANCOVA, analysis of covariance.

Figure 2

Regional fALFF differences between GI-MDD patients and nGI-MDD patients. The color bar indicates the t values from post-hoc t-tests. Red and blue colors denote increased and decreased fALFF, respectively. fALFF, fractional amplitude of low-frequency fluctuation; GI-MDD, major depressive disorder with gastrointestinal symptoms; nGI-MDD, major depressive disorder without gastrointestinal symptoms.

Figure 3

Statistical maps showing the fALFF differences between GI-MDD patients and HCs. The color bar indicates t values from post-hoc t-tests. Red and blue colors denote increased and decreased fALFF, respectively. fALFF, fractional amplitude of low-frequency fluctuation; GI-MDD, major depressive disorder with gastrointestinal symptoms; HCs, healthy controls.

Figure 4

Statistical maps showing the fALFF differences between nGI-MDD patients and HCs. The color bar indicates t values from post-hoc t-tests. Red and blue colors denote increased and decreased fALFF, respectively. fALFF, fractional amplitude of low-frequency fluctuation; nGI-MDD, major depressive disorder without gastrointestinal symptoms; HCs, healthy controls.

Figure 5

Correlations between abnormal fALFF and clinical variables. For all MDD patients, a negative correlation was found between the scores of weight loss in HRSD-17 and the fALFF of the left superior MPFC (A). The severity of GI symptoms was found positively correlated with the fALFF values of the right superior frontal gyrus/middle frontal gyrus (B) and negatively correlated with the fALFF values of the left superior MPFC (C). fALFF, fractional amplitude of low-frequency fluctuation; MDD, major depressive disorder; HRSD-17, 17-item Hamilton Rating Scale for Depression; MPFC, medial prefrontal cortex.

Figure 6

Visualization of the classification using the combination of fALFF values of the left superior MPFC and the right superior frontal gyrus/middle frontal gyrus through SVM. (A) SVM parameter results with 3D view. (B) Classified map of the results. Green crosses represent GI-MDD patients and red crosses represent GI-MDD patients. fALFF, fractional amplitude of low-frequency fluctuation; MPFC, medial prefrontal cortex; SVM, support vector machine; GI-MDD, major depressive disorder with gastrointestinal symptoms; nGI-MDD, major depressive disorder without gastrointestinal symptoms.