Intolerance of Uncertainty and Psychosis: A Systematic Review

Intolerance of uncertainty (IU), the tendency to interpret and react negatively to uncertainty, is a transdiagnostic risk factor for anxiety, depression, and eating-related conditions. Given the high comorbidity between anxiety, depression, and schizophrenia-spectrum diagnoses (SSDs), there is potential for IU to play a role in modulating psychosis symptoms. To address this gap in our understanding, we conducted a systematic review on IU and psychosis within the general population and SSDs. The systematic review identified seven studies (four clinical samples (total n = 453), two student samples (total n = 413), and one at-risk mental state of psychosis sample (n = 35)) that measured IU and psychosis symptoms. Key findings: (1) IU was not associated with measures of total psychotic symptoms, (2) Higher IU in individuals with at risk mental state of psychosis, compared to controls, (3) Higher IU was associated with more psychotic symptoms related to delusions and paranoia within clinical and nonclinical samples, and (4) there was mixed evidence for a relationship between IU and auditory hallucinations (‘hearing voices’) in clinical samples. Overall, these findings highlight that IU may be an important transdiagnostic dimension for psychotic symptoms such as delusions and paranoia in people with SSDs.