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Investigating the meanings and mechanisms of psychotic experiences in young people: a novel, mixed-methods approach

Periodic Reporting for period 2 - iHEAR (Investigating the meanings and mechanisms of psychotic experiences in young people: a novel, mixed-methods approach)

Reporting period: 2018-12-01 to 2020-05-31

At the heart of this study is a wish to better understand experiences of hallucinations and delusions in young people. Hallucinations are sensory and perceptual experiences that involve hearing, seeing, smelling or feeling things that aren’t there and delusions refer thoughts and beliefs that aren’t true, so much so that someone who has them can’t be convinced that they aren’t true. Over the past twenty years, research with children and adolescents in the general population (i.e. recruited from schools and communities and not from mental health services) has revealed that up to 1 in 5 young people may experience some form of hallucination or delusions during their childhood or adolescent years. For most young people, these experiences stop of their own accord and, for many, they are not an indication of any underlying mental health issues or a cause of concern. However, for others, they do seem to be related to their emotional and mental health and they put some young people at risk for developing a range of mental health issues when they are adults, including experiencing depression, feeling suicidal or making a suicide attempt and, for a small minority, developing a psychotic illness.

A number of researchers have been looking at the relationship between hallucination and delusions and experiences of early life stress and traumatic childhood experiences. That research has shown that young people who experience early life stress or trauma - for example, growing up in poverty, experiencing childhood abuse, being bullied in childhood - are at greater risk of experiencing hallucinations and delusions. This project wants to advance our understanding of how and why it is that this relationship exists by looking at multiple aspects of a young person's experience (their subjective views about themselves, their lives and their experiences of hallucinations and delusions, their mental health, their neurocognitive abilities, their stress response and the structure of their brains). It is hope that, by looking at the interplay between early life stress and hallucinations and delusions in this multi-dimensional way, this project will reveal new insights and generate new knowledge about how and why some young people who experience hallucinations and delusions are at higher risk for poorer outcomes in their early adult years.

Findings from this study are important for society because they could help, not only to identify those children and adolescents who are at high risk for poor outcomes later in life, but to identify targets for meaningful early intervention to reduce and minimise that risk.
1. Completion of qualitative data collection
2. Phase 1 qualitative data analysis
3. Presentation of phase 1 qualitative study findings at the IEPA Early Intervention in Psychiatry Conference, Boston, USA, October 2018
4. Publication of qualitative case study analysis of young people with a history of hallucinatory and delusion-like experiences (
5. Analysis on the phenomenological characteristics of hallucinatory and delusion-like experiences completed and paper publushed(

1. Securing of access to full Growing Up in Ireland (GUI) data set for epidemiological analysis
2. Systematic review and meta-analysis of existing studies on psychotic-like experiences and mental disorders completed (
3. Analysis of relationship between self-concept and psychotic-like experiences (
4. Analysis of relationship between psychotic-like experiences and psychopathology. (
5. Analysis of relationship between psychotic-like experiences and functioning. (

1. Development of full assessment protocol for follow-up phase of the Adolescent Brain Development (ABD) Study
2. Recruitment of sample of 100+ individuals from the original ABD study cohort for follow-up
3. Completion of clinical interview and neurocognitive assessments for ABD study follow-up
4. Completion of MRI brain scanning being conducted with ABD study sample participants
5. Analysis of relationship between psychotic-like experiences and fine motor skills (
7. Neurocognitive findings presented at the Schizophrenia International Research Society (SIRS) Conference, Florence, April 2018
8. Neurocognitive findings presenting at the Royal College of Surgeons in Ireland Research Day, 7th March 2019
We are working towards building a conceptual model that will better explain aspects of the relationship between early adversity, psychopathology and hallucinations and delusions in young people.

From our systematic review and meta-analysis we can report that the combined evidence to-date confirms that about 1 in 10 children and adolescents experience hallucinations and delusions. We can further report that these phenomena are associated with a variety of mental health difficulties.

For one of our investigations, we examined the relationship between early adversity and later mental health issues, accounting for participants’ levels of self-worth and of conflict between them and their parent(s). What we found is that conflict between a child and his/her parent(s) is a key mediating factor in the relationship between early experiences of adversity and later mood and anxiety difficulties in young people. In another study, high childhood self-worth was found to reduce risk of early adolescent hallucinations and delusions while, inversely, low childhood self-worth increased the risk of these phenomena in early adolescence.

Looking at hallucinations and delusions as a potential risk factor, one study we conducted found that children who experience hallucinations and delusions are at higher risk of later mental health problems, even when accounting for early adversity and trauma (see paper by Healy et al (2018) Do childhood psychotic experiences improve the prediction of adolescent psychopathology? A longitudinal population‐based study). Another found that children with early hallucinations and delusions were at higher risk of poor functioning, even accounting for underlying psychopathology.

From a neuropsychological perspective, findings from our Adolescent Brain Development study revealed that young people with a history of hallucinations and delusions were more likely to have later deficits in their fine motor skills and their speed of processing.

Our qualitative findings have shown that not all young people who experience hallucinations and delusions have high levels of trauma or adversity. However, those who have are more likely to continue experience these phenomena over time. We have identified qualitative differences in the types and meanings of those experiences for young people. A key finding from this work has been the role of early attachment relationships in the lives of young people who report hallucinations and delusions.

Our work to date has used multiple methods to examine a range of factors that are qualitatively and quantitatively associated with hallucinations and delusions. We have a number of additional investigations underway and planned (including some exploring brain MRI data) that we look forward to reporting on in the coming months.
iHEAR Study Team
iHEAR Study Summary Findings Infographic June 2020
Professor Mary Cannon with Professors Pat McGorry (Australia) and David Cotter (Ireland)
Colm Healy presenting findings at the Irish College of Psychiatrists Conference, April 2019