If we go back over a century to Bleuler’s four “A’s” of schizophrenia (ambivalence, autism, affective incongruity, and association disturbances) (Bleuler, 1911) it is not hard to see a place for dissociation. However, with more modern definitions (e.g. ICD-11) dissociation doesn’t feature as a symptom, with the emphasis now being firmly upon positive and negative symptoms.
There is evidence that patients with psychosis and developmental trauma have worse clinical outcomes and more severe symptoms, in comparison to those without (Bailey et al 2018). Trauma related dissociation is a common clinical consideration, however it doesn’t currently feature as a factor in psychosis.
Within the woodland we have considered Service user experiences of dissociation (2020), Trauma and psychotic experiences: results from a transnational survey (2017) and Trauma and psychotic symptoms: clear association, but do we know why? (2016), but the Venn diagram of psychosis, developmental trauma and dissociation has little evidence base.
The blog today looks at a pair of papers from Melegkovits et al from University College London. A systematic review on the experience and role of dissociation in psychosis following developmental trauma, published in Clinical Psychology Review (Melegkovits et al 2025a) and a qualitative study on the dissociative experiences in individuals with subclinical psychosis and a history of developmental trauma published in the European Journal of Psychotraumatology (Melegkovits et al 2025b).
Patients with the overlap of psychosis and developmental trauma have worse clinical outcomes and more severe symptoms in comparison to those without.
Methods
The systematic review looked for literature in “Embase,” “MEDLINE,” and “PsychINFO” databases (without publication date boundaries), employing predetermined search terminologies.
The qualitative study involved participants with a history of developmental trauma and meeting the criteria for subclinical psychosis, based on the CAPE-15; recruited via social media. Semi-structured interviews were completed online, which were transcribed verbatim and analysed with thematic analysis.
Aims of the systematic review:
- Analyse the association between developmental trauma and dissociation, and compare the prevalence and characteristics of dissociative occurrences among psychotic individuals with and without a history of developmental trauma.
- Investigate the potential intermediary function of dissociation and its subtypes in the nexus between developmental trauma and psychotic experiences across the psychosis continuum.
Aim of the qualitative study:
- To investigate the phenomenology, context, and impact of dissociative experiences in individuals with subclinical psychosis and a history of developmental trauma.
Results
The systematic review identified 40 studies within the search criteria published between 1990 and 2024. Interestingly none of these were qualitative studies. The review involved:
- 6,941 participants
- 26 cross sectional studies
- 10 case control studies
- 4 cohort studies
- 18 were designated with a high risk of bias (ROB)
- 15 with a moderate ROB, and
- 6 as having a low ROB
Elevated levels of developmental trauma and psychosis; small to moderate correlation between developmental trauma and psychotic symptoms.
Higher dissociation levels in clinical psychosis groups; dissociation metrics correlated with positive symptoms, although this wasn’t universal.
Moderate to large correlation between developmental trauma and dissociation; small to moderate correlation between developmental trauma and psychotic symptoms.
Abuse subtypes and dissociation:
- Moderate relationship between sexual abuse and dissociation, r = 0.32 (95 % CI: 0.23 to 0.40).
- Moderate correlation between emotional abuse and dissociation, r = 0.31 (95 % CI: 0.19 to 0.42).
- Small association between physical abuse and dissociation: r = 0.19 (95 % CI: 0.12 to 0.26).
- Small association between physical neglect and dissociation, r = 0.19 (95 % CI: 0.11 to 0.28)
- Small relationship between emotional neglect and dissociation, r = 0.14 (95 % CI: 0.05 to 0.24).
Dose response relationship between developmental trauma and dissociation. Both trauma severity and number of exposures to trauma correlated with increased dissociation.
Dissociation as a mediator between trauma and psychosis:
- Hallucinations. 5 studies provided evidence for mediation of dissociation in the occurrence of hallucinations (only for frequency and quality of hallucinations).
- Delusions and paranoia: Mediation by dissociation was seen in 1/3 clinical samples and 2/2 general population sample
- Negative symptoms: 3 studies linked dissociation and negative symptoms and 2 further studies highlighted the link between developmental trauma and self-reported negative symptoms.
Statistical mediation examines the process by which an independent variable (in this case trauma) affects a dependent variable (psychosis here) through its impact on a third variable, known as a mediator (dissociation).
The qualitative study involved 25 participants from the UK and the thematic analysis yielded the following themes:
Phenomenology of dissociation
- Depersonalisation: awareness, ownership and control of bodily experience
- Depersonalisation: ‘looking at myself from the outside’
- Detachment linked to emotional numbness
- Derealisation phenomenology
- Compartmentalisation phenomenology
Context of dissociation
- As a response to trauma in childhood
- Following trauma reminders
- In response to low mood and distressing emotions
Impact of dissociation
- Highly distressing and threatening experience
- Incomprehensible and confusing
Dissociation and psychotic-like phenomena
- Disconnection…contributing to feelings of mistrust and paranoia.
- Changes in shape, brightness and colour of objects, but also to tactile anomalous experiences akin to hallucinations
- Dissociation as a response to the distress induced by hallucinations
Dissociation may act as a mediator between developmental trauma and psychosis.
Conclusions
The authors concluded that:
We identified a moderate association between developmental trauma and dissociation in psychosis patients, and evidence suggesting that dissociation may mediate the link between developmental trauma and psychosis.
Both studies highlight the complexity of the interplay between dissociative experiences, developmental trauma and psychosis and indicate there may be a specific mediating effect by dissociation in this group.
However, being the first to specifically look into this area it is clear that further research is required to increase our understanding of how dissociation and distress can link to other aspects of psychopathology.
Strengths and limitations
Systematic review
The quality of any systematic review will always be determined by what research has gone before it – both the number of papers and the quality of them. As this is an emerging area of study there will be some natural limitations. However, the processes involved were of a good standard.
The initial study question was quite broad but necessarily so to capture the relevant papers. The paper identification process was robust with major databases used and a PRISMA diagram included in the paper. All types of studies were involved (otherwise I suspect there would have been very few papers), however this does then pose a challenge in relation to articulating the review itself – mainly choosing a narrative process. Risk of bias was completed and reported for all papers using standardised tools depending on the study type. Of the 40 included studies just six had a low risk of bias, while 18 were categorised as high risk and 15 as moderate.
For the meta-analysis, the number of papers in relation to subtypes of developmental trauma became much smaller, which in itself reduces the robustness of the results and the fact that the studies were predominantly cross-sectional removes the ability to imply causal attributes, but it is a good start.
The clinical studies focused on an older demographic and had a lower proportion of females (Mean = 33.26, SD = 10.32; 41 % female) compared to studies on the general population (Mean = 25.25, SD = 7.27; 76.8 % female) which may well impact the validity of the results and generalisability.
Qualitative study
25 participants is a good number of participants for a qualitative study and the research aims were clear and focussed. The study process itself was standardised, semi structured and the inclusion and exclusion criteria were clear.
The selection process has the potential to create some bias: recruiting purely from social media will create selection bias and this does seem to have been the case given the gender imbalance. Self-report scales for assessing the inclusion and exclusion criteria have fallibility and may have led to variation within the selected group.
Within the process of rating whether people were at risk for psychosis they used the CAARMS tool and this does have descriptions of dissociative experiences which the authors do reflect may have led to some inductive bias. However other descriptions were also collated.
The demographics of the population used were mainly young, female participants of white ethnicity and of higher education background, limiting the wider generalisability of the results. This may have been as a result of the sampling method, but future research should seek to explore these experiences in a broader and more representative demographic.
Given the clear focus on phenomenology in the qualitative study, it is hard to understand why a thematic analysis was adopted. Interpretative Phenomenological Analysis (IPA) is a qualitative research methodology rooted in phenomenology and hermeneutics that aims to explore how people make sense of their experiences of a particular phenomenon, which has been used in the past to explore this topic. While it is a time consuming and exacting form of analysis, it may have allowed for a deeper exploration of the lived experience of dissociation.
If the research team had opted to use Interpretative Phenomenological Analysis, it may have allowed for a deeper exploration of the lived experience of dissociation.
Implications for practice
Clinicians are often guided by diagnostic frameworks in relation to symptom correlation and the wider formulation of the patient. With the more modern diagnostic categories for psychotic disorders focusing on the positive and negative symptoms, dissociation (and at times developmental trauma) can be overlooked.
The key take home message from this blog is that clinicians should engage their clinical curiosity and explore for symptoms of dissociation in all patients with psychosis especially if they have a history of developmental trauma.
There is a complexity to articulating dissociative symptoms, however the themes from the qualitative study do start to create a natural language to use, which will be clinically useful. Through the process of writing this blog, I have already amended my own clinical practice and have shared it with the staff I supervise: none of whom would necessarily have considered screening for dissociation in patients with psychosis.
Without a change in clinical practice, the treatment plan for the individual may not be focusing on all the aetiological components, which in turn could lead to poorer outcomes and all of the subsequent ramifications associated with this.
Clinicians should engage their clinical curiosity and explore for symptoms of dissociation in all patients with psychosis, especially if they have a history of developmental trauma.
A little music to listen to whilst we reflect on this…
Statement of interests
I have no conflicting interests in relation to this paper.
Links
Primary papers
Melegkovits 2025a: The experience and role of dissociation in psychosis following developmental trauma: A systematic review Clin Psychol Rev. 2025 Apr:117:102564. doi: 10.1016/j.cpr.2025.102564. https://doi.org/10.1016/j.cpr.2025.102564
Melegkovits 2025b Dissociative experiences in individuals with subclinical psychosis and a history of developmental trauma: a qualitative study . Eur J Psychotraumatol. 2025 Dec;16(1):2472473. https://doi.org/10.1080/20008066.2025.2472473
Other references
Bleuler, E. (1911). Dementia praecox, oder Gruppe der Schizophrenien. Deutsche Zeitschrift für Nervenheilkunde. doi.org/10.1055/s-0031-1295586
Bailey, T., Alvarez-Jimenez, M., Garcia-Sanchez, A. M., Hulbert, C., Barlow, E., & Bendall, S. (2018). Childhood trauma is associated with severity of hallucinations and delusions in psychotic disorders: A systematic review and meta-analysis. Schizophrenia Bulletin, 44, 1111–1122. doi.org/10.1093/schbul/sbx161
