Belief Updating and Paranoia in Individuals with Schizophrenia

Background and Hypothesis: Persecutory delusions are among the most common delusions in schizophrenia and represent the extreme end of the paranoia continuum. Paranoia is accompanied by significant worry and distress. Identifying cognitive mechanisms underlying paranoia is critical for advancing treatment. We hypothesized that aberrant belief updating, which is related to paranoia in human and animal models, would also contribute to persecutory beliefs in individuals with schizophrenia. Study Design: Belief updating was assessed in 42 schizophrenia and 44 healthy participants, using a 3-option probabilistic reversal learning (3-PRL) task. Hierarchical Gaussian filter (HGF) was used to estimate computational parameters of belief updating. Paranoia was measured using the Positive and Negative Syndrome Scale (PANSS) and the revised Green et al. Paranoid Thoughts Scale (R-GPTS). Unusual thought content was measured with the Psychosis Symptom Rating Scale (PSYRATS) and the Peters et al. Delusions Inventory (PDI-21). Worry was measured using the Dunn Worry Questionnaire. Results: Consistent with prior work, paranoia was significantly associated with elevated win-switch rate, prior on volatility and sensitivity to volatility in both schizophrenia and across the whole sample. These relationships were specific to paranoia and did not extend to unusual thought content or measures of anxiety. We did, however, find a significant indirect effect of paranoia on the relationship between prior beliefs about volatility and worry. Conclusions: This work provides evidence that relationships between belief updating parameters and paranoia extend to schizophrenia, may be specific to persecutory beliefs, and contribute to theoretical models implicating worry in the maintenance of persecutory delusions.