Systematic analysis of transdiagnostic epidemiology and clinical correlates of duration of untreated psychosis in the Cavan-Monaghan First Episode Psychosis Study (CAMFEPS)

This thesis first explores similarities and differences between numerous psychosis diagnoses using an epidemiologically based approach. Secondly, it explores relationships between duration of untreated psychosis (DUP), the less studied duration of untreated illness (DUI), developmental indices and measures of clinical, social and functional outcome, with and without controlling for confounders.

Data were collected from first episode psychosis patients within a stable, rural and ethnically homogeneous population over a15-year period (1995-2010) who were incepted into the naturalistic, prospectively designed Cavan-Monaghan First Episode Psychosis Study (CAMFEPS). CAMFEPS incepts all patients aged 16 and older, with no upper age limit, who are resident in counties Cavan and Monaghan, including patients admitted to private hospitals outside of this catchment area or to the national forensic psychiatric hospital. A comprehensive range of standardised assessments was administered at inception and at 6 months to ascertain DSM-IV diagnoses and measure psychopathology, neuropsychology, neurology, quality of life and functioning in relation to DUP and DUI, with a subset of patients followed up at 6 years.

Annual incidence of any DSM-IV psychotic disorder among the 432 cases incepted over the 15 years of CAMFEPS was 34.1/100,000 of population aged ≥15 years and was resolved for each of 12 DSM-IV psychotic diagnoses. Risk for psychosis was higher in males than in females for schizophrenia (3.1-fold) and substance-induced psychosis (7.0-fold) but not for any other diagnosis. Mean DUP for the cohort was 7.5 (range 0.0-192.0) months and mean DUI was 19.4 months (range 0.0-336.0) months, with these durations also resolved for individual psychotic diagnoses. While longer DUP was associated primarily with more severe negative symptoms, DUI was associated with more severe psychopathology across the positive, negative and general domains and with poorer QOL and insight.

Results from this thesis suggest that psychosis, of whatever diagnosis, can emerge at any point across the life-span, in either sex, with similar extents of psychotic psychopathology, and support a dimensional rather than categorical view of psychosis. DUI revealed more robust associations with more severe psychopathology and poorer functional outcome than were evident for DUP. This suggests that DUI may be associated quantitatively with more adverse biological or psychosocial consequences than DUP and should be factored into early intervention programmes.