1.1 Research evidence of the Trauma and Psychosis Relationship
Research has found a high level of trauma exposure in individuals who experience psychosis (Kilcommons & Morrison, 2005; Campodonico et al., 2021; Humphrey et al., 2022; Panayi et al., 2022), leading to significant reported rates of PTSD, and C-PTSD in people with psychosis (Williams et al., 2018; Bloomfield et al., 2022). A dose-response relationship between psychosis, PTSD, and trauma has been repeatedly found (Carr et al., 2018; Larkin & Read, 2008; Matheson et al., 2013; Shelvin et al., 2007; Williams et al., 2018), leading the National Institute for Health and Care Excellence to recommend assessing individuals presenting with an FEP for PTSD and trauma exposure (NICE, 2014).
The literature hypothesises that trauma is a key element of the biopsychosocial model of psychosis (Luhrmann et al., 2019). Childhood traumatic experiences are a risk factor for psychosis (Bentall et al., 2014; Varese et al., 2012; Vila-Badia et al., 2021), with childhood interpersonal traumas being linked to the development and maintenance of psychotic symptoms (Bentall et al., 2014; Garety et al., 2001; Humphrey et al., 2022). Early life trauma may begin a chain of risk factors leading to a psychotic outcome. For instance, Kiburi et al. (2021) in their systematic review found that child trauma increased the risk of cannabis use and the subsequent development of psychosis. Individuals who have experienced trauma are more likely to display risky and challenging behaviours (Grattan et al., 2019), such as self-harm (de Kloet et al., 2011), aggression (Ford et al., 2012), substance use (Ford & Fournier, 2007), and homelessness (Grubaugh et al., 2011).
The type of trauma exposure appears to influence the type and content of psychosis presentations (Grattan et al., 2019; Hardy et al., 2016; Neill & Read, 2022). A link between childhood sexual abuse and auditory hallucinations has been found. A study of 17,337 people found that self-reported adverse childhood experiences doubled the risk of hallucinations (Whitfield et al., 2005) and childhood emotional abuse has been linked to delusions (Hardy et al., 2016). Delusions and hallucinations have been found to be related to negative evaluations of the self and others resulting from traumatic experiences (Kuipers et al., 2006).
Stressful life events which would not meet Criterion A for PTSD, are also a risk factor for developing psychosis (Collip et al., 2010), with workplace stress being found to increase the risk of developing psychosis (Amin, 2023), and adulthood bullying has been linked to positive symptoms (O’Moore et al., 1998).