M114. DELUSIONAL CONTENT AT INITIAL PRESENTATION TO A CATCHMENT-BASED EARLY INTERVENTION SERVICE FOR PSYCHOSIS

BACKGROUND: During a psychotic episode, patients frequently suffer from severe maladaptive beliefs known as delusions. Despite the abundant literature investigating the simple presence or absence of these beliefs, there exists little detailed knowledge regarding their actual content and severity at the onset of illness. Investigating delusions in early clinical samples is critical, because their relatively young, treatment-naïve presentations are less likely to be confounded by the effects of long-term illness or previous interventions. Furthermore, a more detailed view of the association between clinical factors and delusion severity, both globally and per theme, in a larger and more representative sample may improve psychological models and ultimately treatment options. This study reports on delusions during the initiation of indicated treatment for a first episode psychosis (FEP). METHODS: Data were systematically collected from a sample of 637 service users entering an early intervention service for FEP. The FEP service provides a comprehensive standardized assessment battery with longitudinal follow-up for two years of treatment. The average severity and frequency of each delusional theme at baseline was reported using the Scale for Assessment of Positive Symptoms. Delusional severity, both globally and per theme, was examined across a number of sociodemographic and clinical variables. RESULTS: Delusions of a moderate severity or higher were present in the vast majority of individuals experiencing onset of a FEP (94.0%), with persecutory (77.7%), reference (65.5%), and grandiose (40.2%) being the most common themes. Eighty-one percent of service users presented with two or more delusion themes. Persecutory delusions remained consistent in severity across diagnoses, but were more severe with older age of onset (r = .144). No meaningful differences in delusional severity were observed across sex, affective versus non-affective psychosis, or presence/absence of substance abuse or dependence. Global delusion severity was associated with anxiety (r = .205) but not with depression (r = .052), with specific relationships emerging per theme. Delusions commonly referred to as passivity experiences and/or thought alienation, mind reading delusions (r = .242) and delusions of control (r = .247), were related to hallucinatory experiences. We will also examine delusions longitudinally by investigating their relationship to the duration of untreated psychosis and outcomes, along with the stability of delusional content across episodes. DISCUSSION: Unlike the more selected samples, confounded treatment effects, and/or varying levels of chronicity seen in previous reports, this community representative sample offers a rare clinical lens into the severity and content of delusions in FEP. While delusional severity remained consistent across certain sociodemographic and clinical variables, this was not always the case. Future work may wish to investigate the evolution of delusions over time, including focusing on specific themes and/or their overlaps, including with smaller samples and in-depth, phenomenologically oriented interviews.