Emergence and Dynamics of Delusions and Hallucinations Across Stages in Early Psychosis

Hallucinations and delusions are often grouped together as positive symptoms of psychosis. However, recent evidence suggests that they may be driven by distinct computational and neural mechanisms. Examining the time course of their emergence may provide insights into the relationship between these underlying mechanisms.

Participants from the second (N = 719) and third (N = 699) iterations of the North American Prodrome Longitudinal Study (NAPLS 2 and 3) were assessed for timing of clinical high risk for psychosis (CHR-P)-level delusion and hallucination onset. Pre-onset symptom patterns in patients with first-episode psychosis from the Prevention and Early Intervention Program for Psychosis (PEPP-Montréal) (N = 694) were also assessed. Symptom onset was determined at the baseline assessment, and the evolution of symptom patterns was examined over 24 months.

In all 3 samples, participants were more likely to report the onset of attenuated/subthreshold delusions prior to attenuated/subthreshold hallucinations (odds ratios [ORs]: NAPLS 2 = 4.09; NAPLS 3 = 4.14; PEPP, z = 7.01, p < .001) and to present with only attenuated/subthreshold delusions compared with only attenuated/subthreshold hallucinations (ORs: NAPLS 2 = 5.6; NAPLS 3 = 11.11; PEPP = 42.75). The reemergence of attenuated/subthreshold delusions after remission was also more common than reemergence of attenuated/subthreshold hallucinations (ps < .05), which more often resolved first (ps < .001). In both CHR-P samples, ratings of delusional ideation decreased with the onset of attenuated hallucinations (p = .007).

Attenuated/subthreshold delusions tend to emerge before attenuated/subthreshold hallucinations and may play a role in their development. Future work should examine the relationship between the mechanisms that drive these symptoms and its utility for diagnosis and treatment.