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Clinicopathological significance of psychotic experiences in non-psychotic young people: evidence from four population-based studies

  • I. Kelleher (a1), H. Keeley (a2), P. Corcoran (a2), F. Lynch (a3), C. Fitzpatrick (a4), N. Devlin (a1), C. Molloy (a1), S. Roddy (a1), M. C. Clarke (a1), M. Harley (a5), L. Arseneault (a6), C. Wasserman (a7), V. Carli (a8), M. Sarchiapone (a9), C. Hoven (a7), D. Wasserman (a10) and M. Cannon (a11)...
Abstract
Background

Epidemiological research has shown that hallucinations and delusions, the classic symptoms of psychosis, are far more prevalent in the population than actual psychotic disorder. These symptoms are especially prevalent in childhood and adolescence. Longitudinal research has demonstrated that psychotic symptoms in adolescence increase the risk of psychotic disorder in adulthood. There has been a lack of research, however, on the immediate clinicopathological significance of psychotic symptoms in adolescence.

Aims

To investigate the relationship between psychotic symptoms and non-psychotic psychopathology in community samples of adolescents in terms of prevalence, co-occurring disorders, comorbid (multiple) psychopathology and variation across early v. middle adolescence.

Method

Data from four population studies were used: two early adolescence studies (ages 11–13 years) and two mid-adolescence studies (ages 13–16 years). Studies 1 and 2 involved school-based surveys of 2243 children aged 11–16 years for psychotic symptoms and for emotional and behavioural symptoms of psychopathology. Studies 3 and 4 involved in-depth diagnostic interview assessments of psychotic symptoms and lifetime psychiatric disorders in community samples of 423 children aged 11–15 years.

Results

Younger adolescents had a higher prevalence (21–23%) of psychotic symptoms than older adolescents (7%). In both age groups the majority of adolescents who reported psychotic symptoms had at least one diagnosable non-psychotic psychiatric disorder, although associations with psychopathology increased with age: nearly 80% of the mid-adolescence sample who reported psychotic symptoms had at least one diagnosis, compared with 57% of the early adolescence sample. Adolescents who reported psychotic symptoms were at particularly high risk of having multiple co-occurring diagnoses.

Conclusions

Psychotic symptoms are important risk markers for a wide range of non-psychotic psychopathological disorders, in particular for severe psychopathology characterised by multiple co-occurring diagnoses. These symptoms should be carefully assessed in all patients.

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Copyright
Corresponding author
Mary Cannon, Department of Psychiatry, Royal College of Surgeons in Ireland, Education and Research Centre, Beaumont Hospital, Dublin 9, Ireland. Email: marycannon@rcsi.ie
Footnotes
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See editorial, pp. 4–6, this issue.

Declaration of interest

None.

Footnotes
References
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Clinicopathological significance of psychotic experiences in non-psychotic young people: evidence from four population-based studies

  • I. Kelleher (a1), H. Keeley (a2), P. Corcoran (a2), F. Lynch (a3), C. Fitzpatrick (a4), N. Devlin (a1), C. Molloy (a1), S. Roddy (a1), M. C. Clarke (a1), M. Harley (a5), L. Arseneault (a6), C. Wasserman (a7), V. Carli (a8), M. Sarchiapone (a9), C. Hoven (a7), D. Wasserman (a10) and M. Cannon (a11)...
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eLetters

Re: Psychotic experiences - Things to consider

Ian Kelleher
05 December 2012

Thank you to Kostic and colleagues for their interest in our recent paper on the clinicopathological significance of psychotic symptoms (1). There are a number of misunderstandings put forward by the authors, however, that we should clarify. First, it is important to correct the authors with regard to their understanding of the issue of confounding: a confound is a variable of relevance in epidemiological models of causation. To be clear, we did not suggest in our report that psychotic symptoms somehow cause psychiatric disorder. Symptoms and signs of course cannot cause pathology; rather, they act as clinical risk markers for disease. Using an analogy from respiratory medicine, the authors' suggestion that we should control for substance use (which is a potential cause of psychotic symptoms) makes no more sense than suggesting that respiratory researchers should control for cigarette smoking when looking at haemoptysis as a risk marker for lung pathology. That is, haemoptysis alerts the clinician to the likely presence of pathology (i.e., it is a risk marker); the cause of the pathology remains to be determined. Similarly, we showed that psychotic symptoms act as risk markers for a broader range of psychopathology than has generally been recognised (and, in particular, for multimorbid psychopathology). In the same way that there are multiple mechanistic causes for the occurrence of haemoptysis inlung pathology (e.g., cigarette smoking, infection, trauma etc.), there are also likely multiple mechanistic causes for the occurrence of psychotic symptoms in psychopathology. In this regard, we would direct theauthors to paragraph 3 of the discussion section, in which we put forward a number of suggestions for such causes.

Kostic and colleagues also wonder whether the response rate in study 1 or the fact that study 4 specifically over-selected for psychopathology may have affected the validity of these findings. Unfortunately, we do nothave space to provide a comprehensive explanation of the epidemiological impact of response rates on findings; however, it is important to clarify that, while response rates can introduce bias with regard to reported incidences or prevalences, they usually have little effect on statistical measures of association. With regard to study 4, which purposely over-selected for psychopathology, this is, in fact, the very methodological basis of a case-control study. A statistical weight must be applied to determine population prevalences from such an approach but, as evidenced by the many thousands of case-control studies in the medical literature, this does not create problems for identifying associations that can be generalised to the population. Quite aside from this, we would remind the authors that the best way to address the possibility that sampling and other biases are responsible for a set of results is independent replication; our findings were replicated across multiple independent studies, led by multiple independent teams in multiple independent centres. With regard to symptom inclusion, in accordance with the guidelines of the interview instrument (the schedule for affective disorders and schizophrenia for school aged children) (2), hypnopompic, hypnagogic and drug-induced hallucinations were excluded, as were symptomsexperienced only in the context of febrile illness.

Lastly, Kostic and colleagues stated that there was no mention of thepotential role of 'school and family problems' in our findings, although we specifically suggested this as one of a number of important issues in the discussion. In fact, we have already published results from study 4 (in this journal, in fact) on the relationship between psychotic symptoms and a number of measures of school and family problems, including bullying, interparental domestic violence and physical and sexual abuse (3). We cited this in the paper. Furthermore, the authors will be glad to know that a report on the relationship between childhood trauma and psychotic symptoms in another of the samples (study 2) is currently under review (4). However, it is important to recognise that, again, the authorsare raising an issue of causality in the relationship between psychotic symptoms and psychopathology; the point of the current paper, on the otherhand, was to highlight new developments in our understanding of the importance of psychotic symptoms as clinical risk markers for psychopathology.

We appreciate that Kostic and colleagues are certainly not the only individuals who may have had conceptual misunderstandings about the above epidemiological points and we thank them for the opportunity to clarify some of these issues for the benefit of other readers with similar questions. We are also pleased to find that the Journal's readers are actively discussing the importance of assessing psychotic symptoms in the context of non-psychotic psychopathology. As well as recognising that psychotic symptoms are risk markers for a range of non-psychotic Axis-1 disorders in general, and for multimorbidity in particular (1), we would also especially encourage discussion around findings on the importance of these symptoms as risk markers for suicidal behaviour in young people withpsychopathology (5). Considering the serious implications of these findings, an improved awareness of the significance of these symptoms among clinicians is urgently needed.

References

1.Kelleher I, Keeley H, Corcoran P, Lynch F, Fitzpatrick C, Devlin N, Molloy C, Roddy S, Clarke MC, Harley M, Arseneault L, Wasserman C, Carli V, Sarchiapone M, Hoven C, Wasserman D, Cannon M. Clinicopathological significance of psychotic experiences in non-psychoticyoung people: evidence from four population-based studies. Br J Psychiatry. 2012;201:26-32.

2.Kaufman J, Birmaher B, Brent D, Rao U, Ryan N. The schedule for affective disorders and schizophrenia for school aged children: present and lifetime version. University of Pittsburgh, Western Psychiatric Institute and Clinic. 1996.

3.Kelleher I, Harley M, Lynch F, Arseneault L, Fitzpatrick C, CannonM. Associations between childhood trauma, bullying and psychotic symptoms among a school-based adolescent sample. Br J Psychiatry. 2008;193(5):378-382.

4.Kelleher I, Keeley H, Corcoran P, Ramsay H, Wasserman C, Carli V, Sarchiapone M, Hoven C, Wasserman D, Cannon M. Childhood trauma and psychotic symptoms - cause, effect and directionality: results from a prospective cohort study. Submitted.

5.Kelleher I, Lynch F, Harley M, Molloy C, Roddy S, Fitzpatrick C, Cannon M. Psychotic symptoms in adolescence index risk for suicidal behavior: findings from two population-based case-control clinical interview studies. Arch Gen Psychiatry. 2012.

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Conflict of interest: None declared

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Psychotic experiences - Things to consider

Milutin V. Kostic, psychiatry trainee
14 November 2012

Dear Sir,

We have greatly enjoyed reading the article "Clinicopathological significance of psychotic experiences in non-psychotic young people: evidence from four population-based studies" by Kelleher et al. in the July issue of BJP. This is a very interesting study that raises some important questions, but we think that it also has some confounding factors that need to be addressed before conclusions are made. Also, thereare some methodological issues in the study that we would like to be clarified.The response rate in the first study is 52% which might not be enough to make a conclusion for this kind of study. Secondly, due to the different inclusion criteria in studies 1 and 2 there is a strong case for non-response bias. The way in which the first interview sample (study 3) was assembled seems unclear in the paper. Also, how the second interview sample (study 4) was composed leaves questions whether it can truly be considered a sample that represents the general population as claimed in the article.As far as confounding factors go there is no mention of psychoactive substances abuse. With the potential of drugs to produce hallucinogenic effects, and the known link between conduct disorder, depression and ADHD with substance abuse comorbidity 1, there is a chance that this could leadto results that do not reflect the true nature of the link between psychotic symptoms and nonpsychotic disorders. Another thing that could possibly be of interest and could effect the overall conclusions of the study is whether the study made any kind of differentiation between hypnagogic, hypnopompic and daytime hallucinations2. Lastly, there is no mention on the effects of the hallucinations on the children and adolescents, whether they have perceived them as positive, negative or neutral and whether they have sought any help or counseling because of them. There is also no mention of help seeking or school and family problems among the children and adolescents that were classified ashaving a diagnosable non-psychotic disorder which might have been a more precise way to link the severity of childhood and adolescent problems thanthe simple use of the number of comorbid diagnosis assessed in one interview in a nonclinical setting.

1. Zeitlin H. Psychiatric comorbidity with substance misuse in children and teenagers. Drug Alcohol Depend 1999; 1;55(3):225-34.

2. Ohayon MM, Priest RG, Caulet M, Guilleminault C. Hypnagogic and hypnopompic hallucinations: pathological phenomena? Br J Psychiatry 1996; 169(4):459-67.

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Conflict of interest: None declared

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Re: Clinicopathological significance of psychotic experiences in non-psychotic young people

Michael Fitzgerald, Psychiatrist
10 October 2012

Dear Sir,

The article by Kelleher et al on psychotic experiences reminds me of Henry Maudsley comment that "hallucinations may undoubtedly be fugitive events in the history of any child endowed with a highly nervous temperament, as in William Blake, the Engraver, and may not denote any positive disease". Maudsley also notes that his first vision occurred whenhe was eight or nine years of age and was that of a tree with many angels on the tree. However his wife claimed that he had his first vision or hallucination at the age of four when she said "you know, dear, the first time you saw God was when you were four years old and he put his head to the window and set you screaming".

Gilchrist . It is interesting that William Blake had all the featuresof Asperger's Syndrome and these psychotic type phenomena described by Kelleher are very commonly associated with this condition and often mistaken for schizophrenia and treated with life long neuroleptics. I haveseen a number of these patients in their fifties with a diagnosis of schizophrenia who came to me asking me if they had Asperger's Syndrome andit was very clear to me that they had.

Yours sincerely,

Professor Michael Fitzgerald, M.C.004541 Consultant Child & AdultPsychiatrist

I. Kelleher, H. Kealy, P. Corcoran, F. Lynch, C. Fitzpatrick, N. Devlin, C. Molloy, S. Roddy, M. Clarke, M. Harley, L. Arseneault, C. Wasserman, V. Carlimsarchiapone, C. Hoven, D. Wasserman and M. Cannon. Clinicopathological significance of psychotic experiences in non-psychoticyoung people: evidence from four population-based studies. British Journalof Psychiatry 2012 201, 26-32

H. Maudsley 1879 The Biology of Mind. McMillan & Co: London 1879.

Gilchrist Life of Blake

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Conflict of interest: None declared

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