Delusional beliefs in adolescents with anorexia nervosa, obsessive-compulsive disorder, or first-episode psychosis: A comparative study.

Delusional thinking is a key symptom of first-episode psychosis (FEP), but it has also been studied in obsessive-compulsive disorder (OCD) and anorexia nervosa (AN). This study aimed to analyze the psychometric properties of the Brown Assessment of Beliefs Scale (BABS) in a sample of adolescents diagnosed with a FEP, AN, or OCD, and to compare delusional thinking among the three samples. The sample comprised 60 patients in three groups of 20 diagnosed with OCD, AN, or FEP. Participants underwent assessment by diagnostic interview, the BABS scale, and a measure of depressive symptomatology. Specific instruments were also used to assess the main symptomatology of each disorder. The BABS had good internal consistency, and high validity and reliability. The OCD group scored significantly lower than the other two groups in all scale items except for items 4 (fixation of ideas), 6 (insight), and 7 (delusions of reference). A significant difference only existed between the AN and FEP groups for item 7 (delusions of reference). The BABS scale is a valid and reliable tool for assessing delusionality in adolescents diagnosed with OCD, AN, or FEP, with evidence of marked differences between the disorders. Assessing these symptoms could influence management, helping to improve treatment adherence and prognosis.