Psychotic experiences in the population: Association with functioning and mental distress
Introduction
Psychotic experiences are far more common in the population than psychotic disorder (Lin et al., 2011, Saha et al., 2011a, Laurens et al., 2012, Devylder et al., 2013, Cullen et al., 2014). Amongst young people, these experiences most commonly occur in the form of auditory hallucinations, which may be frankly psychotic in nature or, more commonly, attenuated (that is, hallucinatory experiences with intact reality testing) (Kelleher et al., 2011). Psychotic experiences have been found to be important from a number of clinical perspectives. In addition to a relatively increased risk for psychosis (Poulton et al., 2000, Welham et al., 2009, Kaymaz et al., 2012, Fisher et al., 2013), young people with psychotic experiences are at high risk for a range of psychopathological diagnoses (Scott et al., 2009, Yung et al., 2009, Barragan et al., 2011, Werbeloff et al., 2012, Wigman et al., 2012a, Downs et al., 2013). We recently demonstrated in multiple independent samples that the majority of community-based adolescents who reported psychotic experiences met criteria for at least one (non-psychotic) DSM-IV Axis-1 psychiatric disorder (Kelleher et al., 2012b). Similarly, results from the Dunedin longitudinal study showed that the majority of young people who reported psychotic experiences at age 11 had a DSM IV Axis-1 psychiatric disorder at age 38 (Fisher et al., 2013). Whilst there has been some research on functioning in individuals at ‘clinical high risk’ for psychosis (Carrion et al., 2011, Corcoran et al., 2011, Grano et al., 2011), there has been little research to date on global functioning in community samples who report psychotic experiences. Therefore, we wished to investigate the relationship between psychotic experiences and functioning in a general population sample of adolescents.
At a mechanistic level, there are a number of factors that might contribute to poorer functioning in individuals with psychotic experiences. Aside from an overall increased risk of having a diagnosable mental disorder, psychotic experiences are a strong marker of risk for multimorbidity (that is, the presence of more than one disorder), with the prevalence of psychotic experiences increasing in a dose–response manner with the number of diagnosable disorders (Kelleher et al., 2012b), a finding that has been replicated in clinical (Kelleher et al., 2013b) and heterogeneous population samples (DeVylder et al., 2014). What is more, suicidality is highly prevalent amongst individuals with psychopathology who report psychotic experiences, even compared to individuals with the same diagnoses (but who do not report psychotic experiences) (Kelleher et al., 2012c, Kelleher et al., 2014). Neurocognitive deficits have been reported in individuals with psychotic experiences, most notably in processing speed (Blanchard et al., 2010, Cullen et al., 2010, Barnett et al., 2012, Kelleher et al., 2012a), a domain that has previously been highlighted as important more generally in terms of social/role functioning (Carrion et al., 2011). Furthermore, individuals with psychotic experiences have been shown to have significantly more exposure to childhood trauma (Janssen et al., 2004, Scott et al., 2007, Freeman and Fowler, 2009, Arseneault et al., 2011, Galletly et al., 2011, Saha et al., 2011b, Fisher et al., 2012, Wigman et al., 2012b, Kelleher et al., 2013c), something that might also contribute to long term dysfunction.
We also wished to investigate the relationship between psychotic experiences and subjective mental distress. Whilst young people who report psychotic experiences are at increased risk for a range of distressing outcomes (Yung et al., 2006), there has been little research to examine whether psychotic experiences are, in themselves, distressing to the young people who experience them. Notably, Armando et al. found a strong correlation between the frequency of psychotic experiences in a population sample and reported levels of distress (Armando et al., 2010). However, their methodology did not allow them to report the proportion of individuals with psychotic experiences who were distressed by them, nor whether this distress impacted on overall functioning. Therefore, we also investigated what proportion of young people in the population reported feeling distressed by their psychotic experiences and whether distress was related to overall functioning.
Specifically, our hypotheses were:
- (i)
Individuals with psychotic experiences would have poorer global functioning than individuals without psychotic experiences.
- (ii)
Individuals with psychopathology who reported psychotic experiences would have poorer global functioning than individuals with psychopathology who did not report psychotic experiences.
- (iii)
Multimorbid psychopathology, suicidality, neurocognitive dysfunction and trauma exposure would at least partly explain the relationship between psychotic experiences and poorer global functioning.
- (iv)
Psychotic experiences would be distressing for the majority of individuals.
- (v)
The level of distress associated with psychotic experiences would be inversely related to global functioning.
Section snippets
Recruitment
The study was carried out in Dublin, Ireland and neighbouring counties, with testing conducted over three consecutive years during school summer breaks. The study methodology has been previously reported (Kelleher et al., 2012b). However, briefly, a total of 1131 pupils from 16 schools in the 5th and the 6th class (that is, the two most senior years in the Irish national/primary school system), aged 11 to 13 years, participated in a survey of psychiatric symptoms, using the Strengths and
Statistical analyses
Ordered logistic regression was used to investigate the relationship between psychotic experiences and functioning (score on the CGAS). First, univariate analyses were performed to look at the relationship between CGAS score and psychotic experiences. Univariate analyses were also performed to look at the relationship between CGAS score and psychopathology (number of diagnosable disorders), suicidality, childhood trauma and neurocognitive scores on each of the above tasks. Next, we performed a
Results
The mean CGAS score for the total sample was 79 (out of a maximum of 100). There was no relationship between CGAS score and sex or socio-economic status. Sixteen participants had a history of suicidal behaviour (11 individuals with suicidal ideation alone and 5 individuals with suicide plans, 1 of whom had made a suicide attempt). Ten participants had a history of childhood trauma. Seventy three participants had a lifetime diagnosable affective, anxiety or behavioural disorder. The lifetime
Discussion
In a community sample of adolescents, we found a strong relationship between psychotic experiences and global functioning. Young people with psychiatric disorders who reported psychotic experiences scored, on average, more than 10 points lower on the functioning assessment scale than adolescents with psychiatric disorders who did not report psychotic experiences. This indicates that young people with psychopathology who report psychotic experiences are likely to be significantly more
Strengths and limitations
A strength of the current study was the use of a gold-standard diagnostic clinical interview (Kaufman et al., 1996) with assessments conducted by trained mental health professionals. This strength is also a weakness since it is not possible to conduct these types of in-depth diagnostic interviews in the large numbers that are possible with questionnaires or lay interviewers. Although it was not an original hypothesis of the study that individuals with psychotic experiences would have poorer
Conclusions
Psychotic experiences were strongly related to poor functioning, both in the population in general and amongst individuals with psychiatric disorders. In fact, individuals with psychopathology who reported psychotic experiences had a mean functioning score that was more than 10 points lower on the Children's Global Assessment Scale than individuals with psychopathology who did not report psychotic experiences. Furthermore, three quarters of the sample who reported psychotic experiences reported
Role of funding Source
The funding bodies played no role in the collection or analysis of data or in the preparation of this manuscript.
Contributors
IK performed the statistical analyses and wrote the first draft of the paper. All authors contributed to the critical revision of the manuscript and approved the final version.
Conflict of interest
All authors report no conflict of interest.
Acknowledgments
The Adolescent Brain Development Study was supported by an Essel NARSAD/Brain and Behavior Research Foundation Independent Investigator award and a Clinician Scientist Award (CSA/2004/1) from the Health Research Board (Ireland) to M. Cannon.
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