Functional brain abnormalities in patients with somatic symptom disorder presenting with chest pain: a resting-state fMRI study

Somatic symptom disorder (SSD) is characterized by persistent physical symptoms that cannot be fully explained by structural abnormalities or laboratory findings. However, the underlying neural mechanisms of SSD remain poorly understood. This study aimed to investigate functional brain abnormalities in SSD patients presenting predominantly with chest pain using resting-state functional magnetic resonance imaging (rs-fMRI). A total of 102 participants were prospectively enrolled, including 56 patients with SSD and 46 healthy controls (HCs). All participants underwent clinical assessments and structural MRI examinations, including T2-weighted imaging (T2WI), T1-weighted imaging (T1WI), diffusion-weighted imaging (DWI), fluid-attenuated inversion recovery (FLAIR), and rs-fMRI. The rs-fMRI metrics included regional homogeneity (ReHo), amplitude of low-frequency fluctuations (ALFF), and fractional ALFF (fALFF). Group comparisons were conducted to identify differences in brain activity, and correlation analyses were performed to examine associations between brain activity and clinical symptoms. No significant differences were observed between the two groups in demographic variables, including age, gender, and education level. Clinical assessments revealed that SSD patients scored significantly higher than HCs on the Patient Health Questionnaire-15 (PHQ-15), Somatic Symptom Scale (SSS), Generalized Anxiety Disorder-7 (GAD-7), and Hamilton Depression Scale (HAMD). ALFF, fALFF, and ReHo analyses demonstrated significant alterations in spontaneous neural activity in SSD patients compared with HCs. Specifically, increased activity was observed in the left inferior frontal gyrus and precuneus, whereas decreased activity was detected in the hippocampus and insula. Correlation analyses revealed significant associations between these abnormal brain activity patterns and clinical symptom severity in SSD patients. This study highlights regional functional brain abnormalities in SSD, particularly in regions associated with emotion regulation, memory, and sensory processing. These findings provide novel insights into the neural mechanisms underlying SSD and suggest potential neuroimaging targets for therapeutic interventions that may help alleviate symptoms and improve patient outcomes.