Higher cardiovascular activation, but normal heartbeat-evoked potentials and cardiac interoceptive accuracy in somatoform disorders and major depressive disorder

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The perception-filter model posits that the generation of medically-unexplained symptoms is associated with (I.) more intense afferent bodily signals, (II.) impaired filter system activity to differentiate relevant from irrelevant signals, and (III.) altered perception of bodily signals. We tested these assumptions for cardiac perception in patients with somatoform disorders (SFD), patients with major depressive disorder (MDD) and healthy control (HC) individuals. Heart rate (variability; HR/HRV) and blood pressure served as indicators of bodily signals (I.); heartbeat-evoked potentials (HEPs) assessed during a heartbeat counting task (HCT) and a distraction task indicated filter system activity (II.); interoceptive accuracy (IAc) in the HCT was interpreted as an index of perception (III.). All indicators were assessed before and after a socially-evaluated cold pressor stress task (SECPT) and a control intervention. SFD patients (n ​= ​24) showed higher average HR and diastolic blood pressure, as well as lower HRV than HC individuals (n ​= ​22), but there were no differences in HEPs or IAc. Neither were there significant differences between the SFD and the MDD groups (n ​= ​24), nor any stress effect on HEPs or IAc. Our findings suggest that increased intensity of bodily signals (I.) is the only model assumption that could be supported for patients with fully-developed SFD. • We investigated interoception in somatoform disorders (SFD) and depression (MDD). • SFD and MDD patients had higher heart rate (HR) and blood pressure than controls. • Heartbeat-evoked potentials did not differ between SFD, MDD patients and controls. • Cardiac interoception did not differ between SFD, MDD patients and controls. • Acute stress did not affect heartbeat-evoked potentials and cardiac interoception.