Abstract

The negative interpretation of body sensations (e.g., as sign of a severe illness) is a crucial cognitive process in pathological health anxiety (HA). However, little is known about the nature and the degree of automaticity of this interpretation bias. We applied an implicit association test (IAT) in 20 subjects during functional magnetic resonance imaging (fMRI) to investigate behavioral and neural correlates of implicit attitudes toward symptom words. On the behavioral level, body symptom words elicited strong negative implicit association effects, as indexed by slowed reaction times, when symptom words were paired with the attribute “harmless” (incongruent condition). fMRI revealed increased activation in the dorsolateral prefrontal cortex (DLPFC) and posterior parietal cortex for the comparison of incongruent words with control words, as well as with a lower significance threshold also in comparison to congruent words. Moreover, activation in the DLPFC, posterior parietal cortex, nucleus accumbens, and cerebellum varied with individual levels of HA (again, in comparison to control words, as well as with a lower significance threshold also in comparison to congruent words). Slowed reaction times as well as increased activation in dorsolateral prefrontal and posterior parietal cortex point to increased inhibitory demands during the incongruent IAT condition. The positive association between HA severity and neural activity in nucleus accumbens, dorsolateral prefrontal, and posterior parietal cortex suggests that HA is characterized by both intensified negative implicit attitudes and hampered cognitive control mechanisms when confronted with body symptoms.

Highlights

  • Automatic biases in information processing seem characteristic for individuals suffering from mental disorders (American Psychiatric Association, 2000, 2013)

  • It seems reasonable to assume that implicit association test (IAT) effects as found on the behavioral level mainly represent the joint contribution of a bottom-up network consisting of orbitofrontal/medial prefrontal, insular, and limbic-striatal regions, which seem predominately linked to implicit mechanisms of initial stimulus evaluation, and the dorsolateral prefrontal cortex (DLPFC) being involved in top-down control of response conflicts when stimulus response contingencies mismatch the affective evaluation [for a detailed sub-process (Quad) model of automatic and controlled processes, see Beer et al, 2008]

  • Post hoc t-tests indicated that responses to letters were significantly faster compared to words [t(19) = 17.24, p < 0.01; d = 3.35] and that responses were faster in the congruent compared to the incongruent condition [t(19) = 5.55, p < 0.01; d = 0.56]

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Summary

Introduction

Automatic biases in information processing seem characteristic for individuals suffering from mental disorders (American Psychiatric Association, 2000, 2013). In contrast to converging results for especially the DLPFC (and ACC) to be involved in controlled IAT demands (incongruent condition), several approaches to isolate brain regions linked to implicit, automatic mechanisms (congruent condition) found a variety of areas which seem to mediate in particular the processing of the emotional significance of stimulus materials. These areas include (orbitofrontal and medial) prefrontal regions, the insula, and limbic (e.g., amygdala) including striatal (e.g., caudate) structures (Luo et al, 2006; Knutson et al, 2007; Beer et al, 2008). It seems reasonable to assume that IAT effects as found on the behavioral level mainly represent the joint contribution of a bottom-up network consisting of orbitofrontal/medial prefrontal, insular, and limbic-striatal regions, which seem predominately linked to implicit mechanisms of initial stimulus evaluation, and the DLPFC (and ACC) being involved in top-down control of response conflicts when stimulus response contingencies mismatch the affective evaluation [for a detailed sub-process (Quad) model of automatic and controlled processes, see Beer et al, 2008]

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