Unaltered Brain GABA Concentrations and Resting fMRI Activity in Functional Dyspepsia With and Without Comorbid Depression

Abstract

Background: GABA-deficit characterizes depression (MDD), which is highly comorbid with Functional Dyspepsia (FD). We examined brain GABA concentrations and resting activities in post-prandial distress subtype FD (FD-PDS) patients with and without MDD.

Methods: 24 female age/education-matched FD-PDS with comorbid MDD (FD-PDS-MDD), non-depressed FD-PDS, and healthy controls each were compared on GABA concentrations, resting fMRI (fALFF) in bilateral pregenual anterior cingulate (pgACC), left dorsolateral prefrontal cortex (DLPFC), insula, and somatosensory cortex (SSC).

Results: FD-PDS-MDD patients had mild though elevated depressive symptoms. FD-PDS patients had generally mild dyspeptic symptoms. No significant between-group differences in GABA or fALFF were found. No significant correlations were found between GABA and depressive/dyspeptic symptoms after Bonferroni correction. In patients, GABA correlated positively with left insula fALFF (r = 0.38, Bonferroni-corrected p = .03).

Conclusion: We did not find altered GABA concentrations or brain resting activity in FD-PDS or its MDD comorbidity. The neurochemical link between MDD and FD remains elusive.

Keywords: GABA; functional dyspepsia; magnetic resonance spectroscopy; major depressive disorder; resting fMRI.

Figure 1

Positioning of regions of interest in fALFF (Top) and MRS (Bottom) for (A) bilateral pregenual anterior cingulate cortex, (B) left insula, (C) left somatosensory cortex, and (D) left dorsolateral prefrontal cortex.

Figure 2

Group difference in GABA/water in four regions of interest: left dorsolateral prefrontal cortex, left insula, bilateral pregenual anterior cingulate cortex, and left somatosensory cortex.