Psychotic-like experiences and multimorbid psychopathology: The relationship between the 16-item prodromal questionnaire and DSM-IV classifications in a help-seeking population

Aim: Identifying multimorbid psychopathology is necessary to offer more adequate treatment and ultimately reduce the prevalence of persistent mental illnesses. Psychotic symptoms are increasingly seen as a transdiagnostic indicator of multimorbidity, severity and complexity of non-psychotic psychopathology. This study aims to investigate whether psychotic-like experiences and subclinical psychotic symptoms as measured by the 16-item Prodromal Questionnaire are also associated with multimorbid psychopathology. Methods: Participants were help-seeking individuals from outpatient mental healthcare settings and intensive home-treatment teams, aged 17–35. Assessment included the 16-item Prodromal Questionnaire to measure psychotic-like experiences, the Structured Clinical Interview for DSM-IV Axis I, and three sections of the Structured Clinical Interview for DSM-IV Axis II Disorders to determine DSM-IV-TR classifications. The final sample comprised of 160 participants who scored above a cutoff of 6 items on the 16-item Prodromal Questionnaire (HIGH-score) and 60 participants who scored below cutoff (LOW-score). A Poisson Regression was executed to determine the association between the PQ-16 and DSM-IV-TR classifications. Results: The HIGH-score group had a mean of 2.76 multimorbid disorders (range 0–7), while the LOW-score group had a mean of 1.45 disorders (range 0–3). Participants with four to seven disorders scored high on the 16-item Prodromal Questionnaire. Conclusions: Our results suggest that psychotic-like experiences are associated with multimorbidity and severity of psychopathology. Screening for psychotic-like experiences via the PQ-16 in a help-seeking population may help prevent under-diagnosis and under-treatment of comorbid psychopathology.