[Paper Review] Emergence and dynamics of delusions and hallucinations across stages in early psychosis

Catalina Mourgues, David Benrimoh+22 more|arXiv (Cornell University)|Feb 20, 2024

Schizophrenia research and treatmentMedicine3 citations

TL;DR

This longitudinal study across three early psychosis cohorts (NAPLS 2, NAPLS 3, PEPP-Montreal) reveals that delusions consistently precede hallucinations in onset, with delusional symptoms emerging earlier and re-emerging more frequently post-remission. Delusions also decrease in severity at the time of hallucination onset, suggesting a potential causal or developmental role in hallucination emergence.

ABSTRACT

Hallucinations and delusions are often grouped together within the positive symptoms of psychosis. However, recent evidence suggests 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 CHR-P-level delusion and hallucination onset. Pre-onset symptom patterns in first-episode psychosis patients (FEP) from the Prevention and Early Intervention Program for Psychosis (PEPP-Montreal; N = 694) were also assessed. Symptom onset was determined at baseline assessment and the evolution of symptom patterns examined over 24 months. In all three samples, participants were more likely to report the onset of delusion-spectrum symptoms prior to hallucination-spectrum symptoms (odds ratios (OR): NAPLS 2 = 4.09; NAPLS 3 = 4.14; PEPP, Z = 7.01, P < 0.001) and to present with only delusions compared to only hallucinations (OR: NAPLS 2 = 5.6; NAPLS 3 = 11.11; PEPP = 42.75). Re-emergence of delusions after remission was also more common than re-emergence of hallucinations (Ps < 0.05), and hallucinations more often resolved first (Ps < 0.001). In both CHR-P samples, ratings of delusional ideation fell with the onset of hallucinations (P = 0.007). Delusions tend to emerge before hallucinations and may play a role in their development. Further work should examine the relationship between the mechanisms driving these symptoms and its utility for diagnosis and treatment.

Motivation & Objective

• To investigate the temporal sequence of delusion and hallucination onset in individuals at clinical high risk for psychosis (CHR-P) and in first-episode psychosis (FEP) patients.
• To determine whether delusions emerge before hallucinations and whether this pattern is consistent across different stages of early psychosis.
• To examine the dynamics of symptom remission and re-emergence, particularly whether delusions or hallucinations are more likely to recur after symptom remission.
• To explore whether changes in delusional ideation coincide with the onset of hallucinations, suggesting a potential mechanistic link.
• To assess whether distinct symptom patterns at baseline predict differential progression in psychosis onset trajectories.

Proposed method

• Longitudinal assessment of delusion and hallucination onset using standardized clinical interviews at baseline and every 6 months over 24 months in three cohorts: NAPLS 2 (N = 719), NAPLS 3 (N = 699), and PEPP-Montreal (N = 694).
• Symptom onset was determined via clinician-rated assessments using criteria for clinical high risk for psychosis (CHR-P) and first-episode psychosis (FEP).
• Time-to-onset analysis compared the likelihood of delusion-spectrum versus hallucination-spectrum symptom emergence using odds ratios (OR) and survival analysis.
• Symptom evolution was modeled over 24 months, including remission and re-emergence patterns, with statistical testing for differences in recurrence and resolution timing.
• Delusional ideation severity was tracked longitudinally and tested for association with the onset of hallucinations using paired-samples t-tests or non-parametric equivalents.
• Multivariate analysis compared symptom trajectories across cohorts to assess consistency of findings across diverse early psychosis populations.

Experimental results

Research questions

• RQ1 Do delusions typically emerge before hallucinations in individuals at clinical high risk for psychosis (CHR-P) and in first-episode psychosis (FEP) patients?
• RQ2 Is the likelihood of presenting with only delusions higher than with only hallucinations in early psychosis stages?
• RQ3 Which symptom—delusions or hallucinations—is more likely to re-emerge after remission in early psychosis?
• RQ4 Does the onset of hallucinations coincide with a decline in delusional ideation severity?
• RQ5 Do the temporal dynamics of delusion and hallucination emergence support distinct underlying neurocognitive or computational mechanisms?

Key findings

• Delusions emerged before hallucinations in all three cohorts, with adjusted odds ratios (OR) of 4.09 (NAPLS 2) and 4.14 (NAPLS 3) for delusion onset preceding hallucination onset.
• The odds of presenting with only delusions (without hallucinations) were significantly higher than only hallucinations, with ORs of 5.6 (NAPLS 2), 11.11 (NAPLS 3), and 42.75 (PEPP-Montreal).
• Re-emergence of delusions after remission was significantly more common than re-emergence of hallucinations (p < 0.05 across cohorts).
• Hallucinations were more likely to resolve before delusions, with statistically significant differences in resolution timing (p < 0.001).
• In both NAPLS 2 and 3 samples, delusional ideation ratings significantly decreased at the time of hallucination onset (p = 0.007).
• The consistent temporal pattern across diverse early psychosis cohorts supports a developmental role for delusions in the emergence of hallucinations.