Symptoms induced by negative affect in functional somatic syndrome patients: What are the underlying brain activation patterns?

Abstract

Objective. Inducing negative affect through picture viewing increases somatic symptom reporting in patients with functional somatic syndromes (FSS). We investigated the neural mechanisms underlying this effect. Methods. Patients with FSS (fibromyalgia and/or IBS; N=30;) and healthy controls (HC; N=30) watched blocks of neutral, positive and negative affective pictures during functional MRI scanning. Negative affect and somatic symptoms were rated after every picture block. Whole-brain parcelwise robust GLM analysis was used to compare brain activation during negative vs. neutral picture viewing in FSS patients vs HC. Also activation of the neurologic pain signature (NPS) and the picture-induced negative emotion signature (PINES) were compared for the negative affect vs neutral picture contrast. Mediational patterns were explored. Results. During negative (compared to neutral) picture viewing, we observed: (1) higher levels of symptoms, and this effect was stronger in patients compared to HC; (2) stronger activations of somatosensory regions (SI/SII, insular regions) in patients compared to HC; (3) relatively stronger activation of the NPS, but not of the PINES, in patients compared to HC; (4) NPS-mediation of the differences in somatic symptoms between patients and HC. Conclusion. Picture-induced negative affect elicits somatic symptom reports in FSS patients as a result of activation of somatosensory and nociceptive brain patterns. Our findings suggest that affect-related changes in processing of bodily signals are a critical mechanism underlying FSS.