Relationship between functional connectivity and demographic characteristics in patients with functional somatic syndrome with pain: a resting-state fMRI study

Objective. We aimed to investigate the relationship between alterations in spontaneous brain activity and demographic characteristics in patients with functional somatic syndrome (FSS) and associated pain. Materials and Methods. Thirty-four FSS patients participated, each undergoing a 5-min resting-state fMRI scan. We performed seed-based correlation analysis on individual data as the first-level of analysis. The seed regions were the periaqueductal gray, dorsal / rostral anterior cingulate cortex (ACC), insula, amygdala, and posterior cingulate cortex. Multiple regression of group data was performed as the second-level of analysis. The independent variables were age, average pain intensity on a numerical rating scale, pain duration, and hospital anxiety and depression scale (HADS) and pain catastrophizing scale (PCS) scores. Results. Left amygdala-left insula functional connectivity had a significant positive correlation with average pain intensity. Left rostral ACC-left anterior insula functional connectivity was significantly negatively correlated with pain duration. Right amygdala functional connectivity significantly negatively correlated with HADS anxiety scores. Furthermore, functional connectivity of the right amygdala-right parahippocampal gyrus and right rostral ACC-right thalamus were significantly positively correlated with PCS. Conclusions. We found that the functional connectivity of several brain regions related to pain processing relate to the demographic characteristics of FSS patients. This suggests that alterations in spontaneous brain activity relating to pathological pain are modulated by several demographic characteristics. Dysfunction of the brain is one of the pathophysiological mechanisms leading to FSS.