Associations of conservatism/jumping to conclusions biases with aberrant salience and default mode network

Background and hypothesis While 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 design Thirty-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 results We 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. Conclusions Our results support a novel concept that conservatism/JTC biases are associated with aberrant salience of schizophrenia and the default brain mode. ### Competing Interest Statement The authors have declared no competing interest. ### Funding Statement This work was supported by grants from KAKENHI (Japan Society for the Promotion of Science and the Ministry of Education, Culture, Sports, Science and Technology) (grant numbers 26461767, 17H04248, 18H05130, 20H05064, 20K21567, 19H03583, and 21K07544); the Japan Agency for Medical Research and Development Brain/MINDS & beyond studies (grant numbers JP18dm0307008 and JP21uk1024002); the Japan Science and Technology Agency (JST) for the financial support (under Grant No. JPMJMS2021); a Novartis Pharma Research Grant; the SENSHIN Medical Research Foundation; the Uehara Memorial Foundation; the Kyoto University Global Frontier Project for Young Professionals; and the Takeda Science Foundation. ### Author Declarations I confirm all relevant ethical guidelines have been followed, and any necessary IRB and/or ethics committee approvals have been obtained. Yes The details of the IRB/oversight body that provided approval or exemption for the research described are given below: The study design was approved by Kyoto University Graduate School and Faculty of Medicine, Ethics Committee. I confirm that all necessary patient/participant consent has been obtained and the appropriate institutional forms have been archived, and that any patient/participant/sample identifiers included were not known to anyone (e.g., hospital staff, patients or participants themselves) outside the research group so cannot be used to identify individuals. Yes I understand that all clinical trials and any other prospective interventional studies must be registered with an ICMJE-approved registry, such as ClinicalTrials.gov. I confirm that any such study reported in the manuscript has been registered and the trial registration ID is provided (note: if posting a prospective study registered retrospectively, please provide a statement in the trial ID field explaining why the study was not registered in advance). Yes I have followed all appropriate research reporting guidelines and uploaded the relevant EQUATOR Network research reporting checklist(s) and other pertinent material as supplementary files, if applicable. Yes All data produced in the present study are available upon reasonable request to the authors and after MTA.