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Background and hypothesisWhile the conservatism bias refers to the human need for more evidence for decision-making than rational thinking expects, people with schizophrenia and delusion require less evidence, known as the jumping to conclusions (JTC) bias. The midbrain-striatal aberrant salience of schizophrenia is postulated to form delusion; however, the association between conservatism/JTC and aberrant salience and their neural correlates are unclear.Study designThirty-seven patients with schizophrenia and 33 healthy controls performed the beads task, with large/small numbers of bead draws to decision (DTD) used as an index of conservative/hasty (JTC) decisions, respectively. We performed meta-independent component analysis and thresholded dual regression of resting functional magnetic resonance imaging (MRI) data, and structural covariance network analysis (SCNA) of structural and diffusion MRI data. We investigated interactions between diagnosis and DTD, and main effects of DTD for each imaging modality.Study resultsWe found no significant interactions. We identified main effects of DTD (positive correlation) for: 1) functional connectivity between the striatum and default mode network (DMN), 2) DMN-like structural SCNA network, and 3) the diffusion SCNA network connecting networks of 1) and 2) (all p < 0.05, family-wise error [FWE] correction). The functional connectivity between the striatum and DMN was also negatively correlated with delusion severity in patients (p < 0.05, FWE), indicating that the greater the anti-correlation, the stronger the JTC and delusion.ConclusionsOur results support a novel concept that conservatism/JTC biases are associated with aberrant salience of schizophrenia and the default brain mode. |
