A comparison of cognitive biases between schizophrenia patients with delusions and healthy individuals with delusion-like experiences.

BACKGROUND

The role of psychosis-related cognitive biases (e.g. jumping to conclusions) in a delusion continuum is well-established. Little is known about the role of types of cognitive biases. The aim of this study was to investigate the role of psychosis-related and "Beckian" (i.e. anxiety- and depression-related) cognitive biases assessed with a clinical questionnaire in the delusion continuum and its dimensions.

METHODS

Schizophrenia patients with (n=57) and without (n=35) delusions were compared to healthy subjects who had a low (n=53) and high (n=57) level of delusion-like experiences (DLEs) on the Cognitive Biases Questionnaire for Psychosis (CBQp). Delusion dimensions in the clinical sample were assessed with the semi-structured interview PSYRATS. DLEs were measured with the Peters Delusion Inventory (PDI).

RESULTS

High DLEs participants scored significantly higher than low DLEs, and patients with delusions scored higher than patients without delusions on the total scores of the CBQp. High DLEs participants scored significantly higher than low DLEs on catastrophisation and JTC. Schizophrenia patients with delusions scored significantly higher when compared to patients without delusions on intentionalising, dichotomous thinking, JTC and emotional reasoning. Patients with delusions and high DLEs participants scored similarly on JTC. Stepwise regression analysis revealed that catastrophising predicted total severity of clinical delusions and JTC predicted the cognitive dimension of clinical delusions. Both JTC and catastrophisation predicted the frequency and conviction associated with DLEs.

CONCLUSIONS

Both "Beckian" and psychosis-related cognitive biases may underlie delusions. Different aspects of clinical delusions and delusion-like experiences may be related to different cognitive biases.