Due to copyright issues, an electronic copy of the thesis must be ordered from the faculty. For the faculty to have time to process the order, the order must be received by the faculty at the latest 2 days before the public defence. Orders received later than 2 days before the defence will not be processed. After the public defence, please address any inquiries regarding the thesis to the candidate.
Trial Lecture – time and place
See Trial Lecture.
Adjudication committee
- First opponent: Associate Professor Stephen Austin, University of Copenhagen, Denmark
- Second opponent: Professor Erika Jääskeläinen, University of Oulu, Finland
- Third member and chair of the evaluation committee: Associate Professor Linda Wüsthoff, University of Oslo
Chair of the Defence
Associate Professor Emeritus Kjersti Narud, University of Oslo
Principal Supervisor
Professor Ingrid Melle, University of Oslo
Summary
Psychotic disorder not otherwise specified (PNOS) is categorized within the psychosis spectrum, alongside schizophrenia spectrum disorders (SSD) and psychotic bipolar spectrum disorders (PBD). Approximately 10% of patients with psychotic disorders are diagnosed with PNOS. However, this diagnosis is understudied, leading to uncertainty about treatment needs and expected outcomes.
The main aim of this PhD project was to enhance the understanding of psychotic conditions classified as DSM-IV PNOS. The first two studies in the thesis utilized cross-sectional data from the Thematically Organized Psychosis (TOP) study, while the third study employed data from a 10-year follow-up of a longitudinal cohort of first-episode patients.
In the study, participants with PNOS showed intermediate levels of symptom severity and functional impairment compared to those with PBD and SSD. Notably, PNOS participants had a higher prevalence of substance use. The inability to rule out substance-induced psychotic disorder frequently contributed to PNOS diagnoses. Participants with PNOS and SSD reported poorer academic functioning in childhood than those with PBD. Early cannabis use was more common in PNOS and SSD groups, while childhood trauma rates were similar across all groups. At follow-up, higher remission rates and rates of clinical recovery were observed in individuals with baseline PNOS and PBD in comparison to those with SSD. It was noted that 53% of PNOS participants retained their diagnosis at follow-up.
In conclusion, PNOS is a diverse diagnostic category that requires regular reassessment and tailored treatment. Achieving symptomatic remission and clinical recovery is possible for many within the first ten years of treatment, but some may experience a severe illness course leading to re-diagnosis with schizophrenia. Substance use disorders are common among people with PNOS, and it is vital to include substance abuse treatment in their management plan.
Additional information
Contact the research support staff.