Exploring the journey from trauma to psychosis and recovery

Many individuals with psychosis have experienced traumatic events, and a significant proportion develops post-traumatic stress reactions. Post-traumatic stress is an important factor in the onset and persistence of psychosis. Research suggests that trauma-focused therapies (TFTs), such as cognitive restructuring (CR), prolonged exposure (PE), and eye movement desensitization and reprocessing (EMDR), can be effective for people with PTSD and psychosis. This thesis investigates the relationship between trauma, PTSD and psychosis and evaluates the acceptability, effects, and mechanisms of TFTs for people with PTSD and psychosis. Overview of Chapters Chapter 1 introduces trauma, PTSD, and psychosis and describes the TFTs examined in this thesis. Chapter 2 explores the link between childhood victimization and subclinical psychotic symptoms in individuals at high risk for psychosis. Using cluster analysis, four victimization profiles were identified. Severity of childhood victimization was associated with severity of subclinical psychotic symptoms, emphasizing the need for comprehensive trauma assessment in clinical care. Chapter 3 examines recovery trajectories in long-term care. Five patterns of daily functioning were identified: high stable, medium stable, low stable, high declining, and medium increasing. Most individuals remained stable, but upward trajectories were more common than downward ones. Downward trajectories were predicted by non-symptomatic factors (e.g., reduced physical activity), while upward trajectories were linked to symptomatic factors, suggesting that symptom-focused therapies can promote recovery. Chapter 4 investigates PTSD symptom exacerbation during TFT in people with psychosis. Exacerbation was relatively common (32.3%–46.5%) but not associated with poorer outcomes or dropout. Rather than being seen as a barrier to implementation, symptom exacerbations should be acknowledged as part of the therapy process, and guided. Chapter 5 explores the effect of TFT on voice-hearing. Results indicate a small positive effect, even when voices were not directly targeted. Changes in voice-hearing were related to reductions in PTSD symptoms, particularly re-experiencing and trauma-related cognitions. Chapter 6 outlines the RE.PROCESS trial, a randomized controlled trial (RCT) comparing CR, PE, and EMDR for PTSD and psychosis. Chapter 7 presents a qualitative analysis of experiences with TFT. Three themes emerged: (1) factors supporting therapy adherence, (2) valuable therapy processes such as trauma discussion, exposure, and coping strategies, and (3) experiences of symptomatic and personal recovery. These insights can inform implementation strategies. Finally, Chapter 8 provides an overview and discussion of the studies. Research consistently shows that trauma and PTSD are highly prevalent among individuals with psychosis and contribute to both onset and persistence. Overlapping mechanisms such as emotion regulation difficulties, intrusive memories, and negative cognitions, play a role in both conditions. Evidence from case studies and RCTs, including those in this thesis, demonstrates that TFTs can reduce PTSD symptoms and psychosis-related experiences like distressing voices and paranoia. TFTs are safe and acceptable, even though they can be emotionally challenging. Symptom exacerbation should not be viewed as a barrier to implementation; monitoring distress, preparing for possible worsening, and developing support plans can enhance safety and engagement. Specialized clinician training is essential. Future research should focus on integrated approaches combining cognitive-behavioural therapy for psychosis with evidence-based TFTs. It should also investigate therapeutic mechanisms, personalized interventions, and scaling up of implementation across diverse healthcare settings. Large-scale RCTs are underway and will provide critical insights into effectiveness and mechanisms. Including outcomes related to personal and functional recovery will further improve trauma-sensitive care. Conclusion: This thesis underscores the strong link between trauma and psychosis and demonstrates that TFTs are effective, acceptable, and safe when properly supported. Understanding mechanisms and improving implementation are key to advancing integrated, trauma-informed care for individuals with psychosis.