Abnormal Functional Asymmetry in the Salience and Auditory Networks in First-episode, Drug-naive Somatization Disorder.

Evidence of abnormal functional connectivity (FC) has been implicated in patients with somatization disorder (SD). Although the importance of damage to the functional asymmetry has been established, it remains unclear as to whether abnormal intra- and inter-hemispheric FCs are related to patients with SD. We applied resting-state functional magnetic resonance imaging to first-episode, medication-naive patients with SD (n = 25) and matched healthy controls (HCs) (n = 28). The data were analyzed using parameter of asymmetry (PAS) and support vector machine (SVM). Patients with SD showed significantly lower PAS values in the left inferior temporal gyrus (ITG) and higher PAS values in the right insula compared to HCs. A negative correlation was observed between the higher PAS values in the right insula and the Hamilton Depression Scale (HAMD) sleep subscale scores (r = -0.502, p = 0.011), and positive correlations were found between the lower PAS values in the left ITG and the Hamilton Anxiety Scale (HAMA) somatic anxiety subscale scores (r = 0.443, p = 0.027) and the HAMA total scores (r = 0.456, p = 0.022). Moreover, the increased PAS values in the right insula could distinguish patients with SD from HCs with acceptable accuracy (77.36%). First-episode, treatment-naive patients with SD show disrupted asymmetry of inter- and intra-hemispheric FCs. The pattern of disrupted functional asymmetry occurs early in the course of the disease and is independent of medication status, which suggests that disrupted functional asymmetry of salience and auditory networks may be applied as early biological markers for SD.