Similarity and diversity of spontaneous brain activity in functional dyspepsia subtypes.

Background Functional dyspepsia (FD) subtypes may differ in terms of pathophysiology, but the underlying mechanisms remain poorly understood. Purpose To explore spontaneous brain activity in two main FD subtypes, namely epigastric pain syndrome (EPS) and postprandial distress syndrome (PDS), using the amplitude of low-frequency fluctuation (ALFF). Material and Methods Thirty-one FD patients (18 EPS and 13 PDS) and 22 matched healthy controls (HC) underwent resting-state functional MRI scanning. Spontaneous brain activity was evaluated by measuring the ALFF and then compared among the EPS, PDS, and HC groups with ANOVA test. Pearson correlation analysis was performed between the ALFF values and clinical indices. Results Compared to healthy controls, both EPS and PDS patients had increased ALFF in the bilateral precentral/postcentral gyri, insula, and thalami. Furthermore, only the EPS patients displayed increased ALFF in the right middle and inferior frontal gyri, and only the PDS patients showed increased ALFF in the left posterior cingulate cortex (PCC). The ALFF values in the left thalamus were positively correlated with the sleep disturbance in EPS patients, and the ALFF values in the right precentral/postcentral gyri showed a positive correlation with the symptom score in PDS patients. Conclusion EPS and PDS had similarities of higher spontaneous brain activity in the primary motor/sensory areas and homeostatic-afferent network regions, and differences in the prefrontal region and PCC, providing evidence to suggest the similarity and diversity of pathophysiology in FD subtypes.