Screening for the at-risk mental state in young people
: Identifying psychosis-risk with the prodromal questionnaire-16 (PQ-16)

  • Clare Howie

Student thesis: Doctoral ThesisDoctor of Philosophy


Psychosis can be debilitating for those affected and can have impacts on wider society and early identification and intervention for psychosis can improve outcomes for individuals with psychotic disorders. Research over the last century has shown that there is a prodromal period before the onset of psychotic disorders and this has become a target for researchers and clinicians to identify this prodromal period and intervene at this point. The at-risk mental state is a concept developed in the 1990s which described subthreshold psychotic symptoms and aimed to identify those at-risk of psychosis and offer intervention. Clinics can offer assessment and intervention for those referred to their services, but further work needs to be done to identify those who are not help-seeking but still distressed by attenuated symptoms. Screening measures for the at-risk mental state may provide a means of reducing time for assessment and the use of screening in non-clinical settings may identify more individuals at-risk of psychosis, and at an earlier stage.
Aims and methods
This thesis is comprised of four original studies to examine the use of screening in non-clinical settings and the suitability of a specific screening measure for the at-risk mental state: The Prodromal Questionnaire-16 (PQ-16). Chapter 3 is a systematic review conducted to identify what screening has been conducted within educational settings, how screening has been conducted, particularly what screening measures have been implemented, and to explore the need for further research within this area. Two factor analytic studies were conducted to examine the structure of the PQ-16 in two non-clinical populations. Chapter 4 examined the structure of the PQ-16 in a sample (N=1045) who completed the study through Amazon’s Mechanical Turk, with an average age of 27 years. Chapter 5 examined the structure of the PQ-16 in a sample (n=1165) who completed the PQ-16 as part of the Northern Ireland Youth Wellbeing Survey, with an average age of 15 years. It also determined if there were any differences in the structure of this screening measure between these two cohorts. Chapter 6 aimed to examine the association between adverse and benevolent childhood experiences and attenuated psychotic symptoms in a youth population sample (n=1165), using the PQ-16 to identify attenuated symptoms. This is to identify if there are certain experiences that are present in those who experience attenuated psychotic symptoms and clinicians and researchers should be aware of when screening for these symptoms.
The systematic review provided evidence that screening for the ARMS has been conducted within educational settings and the rate of individuals at-risk of psychosis in these settings vary. For clinicians and researcher using the PQ-16 in educational settings, the use of different cut-off scoring for follow-up assessment should be considered to avoid a high rate of false positives. Chapter 4 identified a three-factor model representing perceptual abnormalities/hallucinations, unusual thought content, and negative symptoms appeared to be a better fit for the data in this study. Chapter 5 indicated a two-factor structure in the PQ-16 in this study. Factor 1 represented hallucinations and factor 2 represented perplexity/anxiety. This highlighted that there was a difference in how the PQ-16 is structured across two age groups in non-clinical settings. Chapter 6 identified that prodromal symptoms as identified by the PQ-16 were associated with childhood abuse and neglect, and benevolent childhood experiences were negative predictor of symptoms.
The aim of this thesis was to examine the role of screening for psychosis prevention, specifically the use of the Prodromal Questionnaire-16 and its suitability for screening for the at-risk mental state. The use of the PQ-16 as a screening measure in non-clinical settings is appropriate but its use should be adapted depending on the population due to the potential differences in structure and the need for differing cut-off scores. The co-occurrence of childhood adversities with prodromal symptoms should be considered when researching the at-risk mental state in non-clinical settings.

Date of AwardJul 2022
Original languageEnglish
Awarding Institution
  • Queen's University Belfast
SponsorsNorthern Ireland Department for the Economy
SupervisorCiaran Mulholland (Supervisor), Gavin Davidson (Supervisor) & Ciaran Shannon (Supervisor)


  • psychosis
  • at-risk mental state
  • screening
  • prodromal symptoms
  • Prodromal Questionnaire-16

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