Do trauma-focussed psychological interventions have an effect on psychotic symptoms? A systematic review and meta-analysis
Introduction
There is mounting evidence that exposure to traumatic or adverse experiences in childhood represents a significant risk factor in the development of psychosis (Bendall et al., 2008, Read et al., 2001, Varese et al., 2012) and there is thematic correspondence between the content of psychotic experiences and significant past life events (Corstens and Longden, 2013, Hardy et al., 2005, McCarthy-Jones et al., 2014). There is also compelling evidence to suggest a relationship between posttraumatic stress disorder (PTSD, arguably the ‘hallmark’ disorder caused by traumatic events) and psychosis, including high rates of comorbidity (Sareen et al., 2005) and PTSD being a risk factor for the development of psychosis (Okkels et al., 2017).
This relationship suggests similar mechanisms could be involved in psychotic experiences and symptoms of PTSD (Morrison et al., 2003). For example, it has been proposed that auditory hallucinations are a type of posttraumatic intrusion, contributed to by contextual processing difficulties (Hardy, 2017, Steel et al., 2005). Additionally, dissociation (Moskowitz and Corstens, 2007) and negative posttraumatic beliefs (Gracie et al., 2007) have been implicated in the development of auditory hallucinations. Similar psychological mechanisms are also implicated in the development of delusional experiences and PTSD symptoms following a traumatic event (Freeman et al., 2013), whilst negative symptoms have been conceptualized as manifestations of trauma-related avoidance (McGorry, 1991).
Trauma-focussed (TF) interventions are effective in treating PTSD (Bisson et al., 2007). Given potential mechanistic overlaps between PTSD and psychosis TF treatments represent a new direction in treatment development for psychosis. This aligns with mental health service-user calls for therapeutic approaches that consider psychosis in the context of past life experiences (Corstens et al., 2014). Recently, researchers have begun to apply TF treatments to comorbid PTSD and other trauma-related symptoms in people with psychotic disorders. Whilst evidence remains too limited for a Cochrane review to draw any meaningful conclusions (Sin et al., 2017), two recent reviews have concluded that TF treatments can be used safely and effectively reduce PTSD symptoms in this population (Sin and Spain, 2016, Swan et al., 2017). Emerging data also suggests that TF treatments may have an impact on psychotic symptoms, but this is yet to be systematically synthesized across studies. We examined the literature on TF treatments conducted within psychosis populations to determine whether these interventions have an effect on psychotic symptoms.
Section snippets
Methods
The review was prospectively registered with the International Prospective Register of Systematic Reviews (PROSPERO), protocol no: CRD42016035827 and is reported in accordance with PRISMA guidelines.
Results
The database search yielded 4399 records. Once duplicates were removed, 3236 records were screened on titles and abstracts. Forty-one full text records were assessed. An additional two ‘in press’ studies were identified through contact with the authors (de Bont et al., 2016, Steel et al., 2016). Twenty-five articles were included in the final review. Fig. 1 displays the PRISMA flow-chart of the selection process.
Primary outcomes: do TF therapies have an effect on the symptoms of psychosis?
The results of the meta-analysis suggest that TF treatments have a small, significant effect on the positive symptoms of psychosis immediately following treatment. The between-group effect size of 0.31 post-treatment is notable, since it is within the range of effect sizes usually reported for current best-practice CBT for psychosis when compared with TAU (Jauhar et al., 2014, van der Gaag et al., 2014, Wykes et al., 2008). However, the fact that this between-group effect was not maintained at
Contributors
RB designed the review, wrote the protocol, managed the literature searches, quality checks and analyses and led the write up of the manuscript. NT provided methodological and content advice throughout the process of the review. Author CM was a second rater in screening articles for inclusion, rating risk of bias and GRADE assessments. Authors SB and SR had input to protocol development and writing up the final manuscript. All authors contributed to and have approved the final manuscript.
Conflict of interest
The authors have no conflicts of interest to declare.
Acknowledgements
We thank all of the authors of the original studies included in the review for kindly providing the data necessary for our analysis.
Funding source declaration
The first author is funded by a Swinburne University of Technology PhD scholarship.
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