The Neuroanatomy of Somatoform Disorders: A Magnetic Resonance Imaging Study

Abstract

Background: Somatoform disorders (SDs) 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 SDs are still inconclusive.

Objective: 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 SDs 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 the 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 SDs 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.

Keywords: MRI; clinical profile; cognition; gray matter; somatoform disorder.