Brain Functional Connectivity in Patients With Somatic Symptom Disorder

The aim of the study was to evaluate whether individuals with somatic symptom disorder (SSD) display increased resting-state functional connectivity (FC) within and between the sensorimotor network (SMN), default mode network (DMN), salience network, and dorsal attention network (DAN).

Eighteen patients with SSD and 20 age- and sex-matched healthy control participants underwent resting-state functional magnetic resonance imaging. We used a seed-based correlation approach for the four brain networks.

Patients with SSD had higher scores on the Somato-Sensory Amplification Scale (z = 5.22, p < .001) and Symptom Checklist-90-Revised-Somatization (z = 4.94, p < .001) and greater FC within the SMN, DMN, and salience network than healthy control participants. Patients with SSD also had increased FC between the SMN and DMN, SMN and salience network, SMN and DAN, and salience network and DAN (t = 5.10-7.47, all false discovery rate q < .05). The Somato-Sensory Amplification Scale scores correlated with FC between the SMN and salience network and between the SMN and DAN (r = .61-.82, all p < .003).

Based on the results of the FC analysis between the SMN and salience network, we suggest that SSD may be associated with alterations of sensory-discriminative processing of pain and other somatic symptoms, which is influenced by affective processing. Based on the results of the FC analysis of the SMN and DAN, we suggest that patients with SSD have a deficit in attention, leading to misperception of external stimuli and failure to regulate bodily functions aimed at interactions with external stimuli.