Support for Predictive Processing Assumptions on Health Anxiety: Imprecise Expectations on the Origin of Somatic Symptoms Increase Health Anxiety

Objective: In pathological health anxiety (pHA), a more liberal interoceptive response bias and health-threat related biases are observed. In predictive processing terms, this could be translated into a precise prior on high somatic symptom probability (symptom-prior) and an imprecise prior on one’s current (and future) health state (hidden-state-prior). Methods: In an online experiment, we used an adapted version of the Affect and Symptom Paradigm (ASP), previously shown to sufficiently elicit somatic symptoms. N =261 participants (Age: M =27.79, SD =9.61; Gender: 77.8% female, 21.5% male, 0.8% divers) were randomly assigned to four conditions, manipulating priors on somatic symptom probability (symptom-prior: precise and high probability vs. precise and low probability) and origins of somatic symptoms (hidden-state-prior: imprecise vs. precise and non-illness). Results: We did not observe any significant effects of symptom-prior manipulation on symptom report ( P =0.27). Inducing an imprecise prior on the origin of somatic symptoms (imprecise hidden-state-prior), though, was significantly associated with higher health anxiety after negative (compared to neutral) pictures in people with higher pre-existing health anxiety ( b =0.113, SE =0.045, 95% BCa CI [0.025, 0.201]). This effect was not attributable to a simultaneous change in valence or arousal ( p val =0.73; p aro =0.56). Conclusions: The findings suggest a possible central role of imprecise priors, especially on one’s health state, in pHA. Further evidence in clinical samples is needed.