The Neuroanatomy of Somatoform Disorders: A Magnetic Resonance Imaging Study

Background: Somatoform Disorders (SD) are a heterogeneous group of psychiatric syndromes characterized by common symptoms, which may mimic a physical condition but they are not explained by a medical condition. Although the biologic nature of this disorder has been widely accepted, the neuroanatomical correlates characterizing SD are still inconclusive. Therefore, this study aims to explore gray matter (GM) volume alterations in SD patients compared to healthy controls and their possible association with clinical and cognitive measures. Method: We used voxel-based morphometry to examine regional GM volumes in 20 inpatients with SD and 24-matched healthy controls. Only for SD patients, we employed multiple instruments to assess psychopathology and cognitive functioning, which were then used to explore their association with GM volume deficits. Results: Compared to healthy controls, SD patients showed GM volume reductions in hypothalamus, left fusiform gyrus, right cuneus, left inferior frontal gyrus, left posterior cingulate, and right amygdala (p < 0.05, cluster Family Wise Error corrected). Additionally, in SD, Symptom Checklist-90-Phobia and Hamilton Depressive Rating Scale scores negatively correlated with specific fronto-temporoparietal regions whereas Symptom Checklist-90-Sleep scores positively correlated with anterior cingulate cortex. Lastly, the Boston Naming Test negatively correlated with fronto-temporoparietal and striatal volumes whereas Free and Cued Selective Reminding Test and Stroop scores positively correlated with superior temporal gyrus and cuneus, respectively (all p < 0.05, cluster Family Wise Error corrected). Conclusion: Our results suggest that SD might be characterized by selective impairments in specific cortico-limbic regions associated to two overlapping circuits, the neuromatrix of pain and the emotion regulation system.