Self-reported cognitive distortions in the psychosis continuum: a Polish 18-item version of the Davos Assessment of Cognitive Biases Scale (DACOBS-18)

Aim: The aim of this study was to provide a short version of the Davos Assessment of Cognitive Biases Scale (DACOBS), which is a self-report tool to assess cognitive distortions related to psychosis. Methods: A principal component analysis (PCA) was conducted on a large non-clinical sample (n = 1207) and cross-validated with a confirmatory factor analysis on an independent non-clinical sample (n = 653). Discriminative validity was performed by contrasting the high risk for psychosis non-clinical sample (n = 63), low risk for psychosis non-clinical sample (n = 152), patients with schizophrenia (n = 105), and patients with depression (n = 56). Correlations between symptoms, cognitive functions, source monitoring deficits, and jumping to conclusions were performed among a subgroup of patients with schizophrenia. Results: An 18-item scale (DACOBS-18) with a four-factor solution was established. Internal consistency (α = 0.84) and test-retest reliability (r = 0.84, p <. 0.001) were good. The DACOBS-18 has satisfactory discriminative power, with 99.1% sensitivity and 74.3% specificity in discriminating low risk for psychosis from schizophrenia patients. The DACOBS-18 subscales correlate significantly with psychotic symptoms and psychotic-like experiences. After Bonferroni correction, significant correlations between Safety Behaviors and neuropsychological functioning were found. Conclusions: The DACOBS-18 is a reliable scale with satisfactory discriminative power and thus may be a valuable self-report screening tool for use in everyday clinical practice with psychotic patients and with people at risk for psychosis. Further research on its relationship to objective cognitive measures is needed.