People With Atypical Psychosis Share More Risk Factors With Schizophrenia Than Bipolar Disorder

In a study of 1,099 people with psychotic disorders, those with atypical presentations (PNOS) had early cannabis use rates and academic difficulties more similar to schizophrenia than to psychotic bipolar disorder.

Widing, Line et al.·Comprehensive psychiatry·2022·Moderate EvidenceCross-Sectional
RTHC-04300Cross SectionalModerate Evidence2022RETHINKTHC RESEARCH DATABASErethinkthc.com/research

Quick Facts

Study Type
Cross-Sectional
Evidence
Moderate Evidence
Sample
N=1,099

What This Study Found

17.5% of PNOS participants and 11.5% of schizophrenia spectrum participants used cannabis before age 16, compared to only 5.3% of psychotic bipolar participants. PNOS and schizophrenia groups also had poorer premorbid academic functioning than the bipolar group.

Key Numbers

1,099 participants total; 17.5% of PNOS used cannabis before 16 vs 11.5% SSD vs 5.3% PBD; premorbid academic functioning significantly worse in PNOS and SSD vs PBD (F=7.81, p<0.05); childhood adversity rates were high across all three groups with no significant differences

How They Did This

Cross-sectional study of 1,099 participants from the Norwegian TOP-study: 688 with schizophrenia spectrum disorders, 274 with psychotic bipolar spectrum disorders, and 137 with psychotic disorder not otherwise specified (PNOS). Assessed using SCID-I diagnostic interviews, Premorbid Adjustment Scale, cannabis use history, and Childhood Trauma Questionnaire.

Why This Research Matters

Psychotic disorder NOS is a common but poorly understood diagnosis. Understanding whether these patients look more like schizophrenia or bipolar patients in their early histories can guide treatment decisions and help predict outcomes.

The Bigger Picture

This adds to evidence that early cannabis use clusters with certain psychosis subtypes. The finding that PNOS patients resemble schizophrenia patients more than bipolar patients suggests these conditions may share developmental pathways.

What This Study Doesn't Tell Us

Cross-sectional design cannot establish whether early cannabis use contributed to the psychotic disorder. Self-reported cannabis use history may be subject to recall bias. PNOS is a heterogeneous diagnostic category.

Questions This Raises

  • ?Does early cannabis use contribute to the development of PNOS, or do shared genetic vulnerabilities explain both?
  • ?Would reclassifying PNOS patients based on premorbid factors improve treatment outcomes?

Trust & Context

Key Stat:
1,099 participants across 3 diagnostic groups
Evidence Grade:
Large sample from a well-established research cohort, but cross-sectional design limits causal inference
Study Age:
2022 study
Original Title:
Premorbid characteristics of patients with DSM-IV psychotic disorders.
Published In:
Comprehensive psychiatry, 115, 152310 (2022)
Database ID:
RTHC-04300

Evidence Hierarchy

Meta-Analysis / Systematic Review
Randomized Controlled Trial
Cohort / Case-Control
Cross-Sectional / ObservationalSnapshot without intervening
This study
Case Report / Animal Study

A snapshot of a population at one point in time.

What do these levels mean? →

Frequently Asked Questions

Does cannabis before age 16 cause psychosis?

This study cannot answer that question directly. It found an association between early cannabis use and certain psychosis subtypes, but the cross-sectional design cannot determine causation.

Were childhood trauma rates different across the groups?

No. All three groups had similarly high rates of childhood adversity, suggesting trauma is a shared risk factor across psychotic disorders regardless of subtype.

Read More on RethinkTHC

Cite This Study

RTHC-04300·https://rethinkthc.com/research/RTHC-04300

APA

Widing, Line; Simonsen, Carmen; Flaaten, Camilla B; Haatveit, Beathe; Vik, Ruth Kristine; Wold, Kristin F; Åsbø, Gina; Ueland, Torill; Melle, Ingrid. (2022). Premorbid characteristics of patients with DSM-IV psychotic disorders.. Comprehensive psychiatry, 115, 152310. https://doi.org/10.1016/j.comppsych.2022.152310

MLA

Widing, Line, et al. "Premorbid characteristics of patients with DSM-IV psychotic disorders.." Comprehensive psychiatry, 2022. https://doi.org/10.1016/j.comppsych.2022.152310

RethinkTHC

RethinkTHC Research Database. "Premorbid characteristics of patients with DSM-IV psychotic ..." RTHC-04300. Retrieved from https://rethinkthc.com/research/widing-2022-premorbid-characteristics-of-patients

Access the Original Study

Study data sourced from PubMed, a service of the U.S. National Library of Medicine, National Institutes of Health.

This study breakdown was produced by the RethinkTHC research team. We analyze and report published research findings without making health recommendations. All interpretations are based solely on the published abstract and study data.