Core beliefs in psychosis: a systematic review and meta-analysis.

Increasing interest is growing for the identification of psychological mechanisms to account for the influence of trauma on psychosis, with core beliefs being proposed as a putative mediator to account for this relationship. A systematic review (n = 79 studies) was conducted to summarise the existing evidence base regarding the role of core beliefs/schemas in psychosis, Clinical High-Risk (CHR), and non-clinical samples with Psychotic-Like Experiences (PLEs). Compared to Healthy Controls (HCs), individuals with psychosis experiencing Auditory Hallucinations or Persecutory Delusions had significantly higher scores for negative self and negative other-beliefs and significantly lower scores for positive self and positive other-beliefs. This pattern of core beliefs was also observed for CHR individuals. In contrast, the core belief profile for grandiose delusions was in the opposite direction: higher positive self and positive other-beliefs and lower negative self-beliefs. In non-clinical samples, several factors mediated the relationship between Traumatic Life Events (TLEs) and PLEs, such as greater perceived stress, dissociation, external locus of control, and negative self and negative other-beliefs. Compared to HCs, meta-analyses revealed statistically significant large effects for negative self and negative other-beliefs in Schizophrenia. In CHR, statistically significant large and moderate effects were found for negative self and negative other-beliefs, respectively, along with a moderate negative effect for positive self-beliefs. Core beliefs were found to play a significant role in the development and maintenance of positive symptoms of psychosis. The development of psychosocial interventions that explicitly target negative self and other-beliefs, whilst also enhancing positive self-beliefs are warranted and would innovate CBTp practices.