Jumping to Conclusions, Neuropsychological Functioning, and Delusional Beliefs in First Episode Psychosis

Background: The "jumping to conclusions" (JTC) data-gathering bias is implicated in the development and maintenance of psychosis but has only recently been studied in first episode psychosis (FEP). In this study, we set out to establish the relationship of JTC in FEP with delusions and neuropsychological functioning. Methods: One hundred and eight FEP patients and 101 age-matched controls completed assessments of delusions, general intelligence (IQ), working memory (WM), and JTC (the probabilistic reasoning "beads" task). Results: Half the FEP participants jumped to conclusions on at least 1 task, compared with 25% of controls (OR range 2.1 to 3.9; 95% CI range 1.5 to 8.0, P values ≤ .02). JTC was associated with clinical, but not nonclinical delusion severity, and with neuropsychological functioning, irrespective of clinical status. Both IQ and delusion severity, but not WM, were independently associated with JTC in the FEP group. Conclusions: JTC is present in FEP. The specific association of JTC with clinical delusions supports a state, maintaining role for the bias. The associations of JTC with neuropsychological functioning indicate a separable, trait aspect to the bias, which may confer vulnerability to psychosis. The work has potential to inform emerging interventions targeting reasoning biases in early psychosis.