Neural correlates of somatoform disorders from a meta-analytic perspective on neuroimaging studies

Abstract

Somatoform disorders (SD) are common medical disorders with prevalence rates between 3.5% and 18.4%, depending on country and medical setting. SD as outlined in the ICD-10 exhibits various biological, social, and psychological pathogenic factors. Little is known about the neural correlates of SD. The aims of this meta-analysis are to identify neuronal areas that are involved in SD and consistently differ between patients and healthy controls. We conducted a systematic literature research on neuroimaging studies of SD. Ten out of 686 studies fulfilled the inclusion criteria and were analyzed using activation likelihood estimation. Five neuronal areas differ between patients with SD and healthy controls namely the premotor and supplementary motor cortexes, the middle frontal gyrus, the anterior cingulate cortex, the insula, and the posterior cingulate cortex. These areas seem to have a particular importance for the occurrence of SD. Out of the ten studies two did not contribute to any of the clusters. Our results seem to largely overlap with the circuit network model of somatosensory amplification for SD. It is conceivable that functional disorders, independent of the clinical impression, show similar neurobiological processes. While overlaps do occur it is necessary to understand single functional somatic syndromes and their aetiology for future research, terminology, and treatment guidelines.

Keywords: ALE; Activation likelihood estimation; Anterior cingulate cortex; Insula; MRI; Meta-analysis; Middle frontal gyrus; Neuroimaging; Posterior cingulate cortex; Premotor area; Somatoform disorders; Somatoform pain disorders; Supplementary motor cortex.

Graphical abstract

Fig. 1

Flow chart of review process. Number of publications (n) and number of individuals (N) are indicated.

Fig. 2

Results of the activation likelihood estimation (ALE) of A) functional studies and B) of functional and structural scans. Five areas were identified that were consistently differential in the comparison between healthy controls and patients with pain-related somatoform disorder (the premotor and supplementary motor cortexes, anterior prefrontal cortex, anterior cingulate cortex, insula, dorsal posterior cingulate cortex). Differential areas in A) functional analysis are dorsal posterior cingulate cortex, anterior prefrontal cortex, and insula and in B) functional and structural analysis the anterior prefrontal cortex, premotor and supplementary motor cortex (including lateral and medial supplementary cortex), dorsal posterior cingulate cortex, anterior cingulate cortex. Z coordinates in Talairach space are reported. Scale bar shows z-scores of ALE statistics with increasing significance from left to right. Only significant clusters are indicated with a cluster level above 0.05 and a p-value below 0.001.