Past meta-analyses have confirmed robust associations between childhood traumatic experiences and the risk of psychosis. However, the dose–response relationship between cumulative adversity exposure and psychosis risk observed in some, but not all, previous studies in this area has not been specifically scrutinized or substantiated via recommended meta-analytic methods. This meta-analysis aimed to synthesize the available evidence on dose–response effects between childhood trauma and psychosis outcomes.

PsycINFO, PubMed, EMBASE, Web of Science, CNKI, and WANFANG were searched from inception to July 2024 to identify observational studies reporting odds ratios for psychosis outcomes across multiple levels of childhood trauma exposure. Dose–response effects were extracted from eligible studies and synthesized via robust error meta-regression analyses.

Twenty-one studies comprising 59,975 participants were included in the meta-analysis. A significant nonlinear relationship was observed between the number of childhood adversities and the risk of future psychosis experiences (p for nonlinearity = .021). The pooled odds ratio for psychosis increased from 1.76 (95% confidence interval [CI]: 1.39–2.22) for 1 exposure to 6.46 (95% CI: 4.37–9.53) for 5+ exposures compared to no traumatic experience.

This meta-analysis provides robust evidence for a dose–response relationship between cumulative childhood adversity and psychosis risk, with nonlinear patterns suggestive of an accelerating, more pronounced, risk at higher levels of trauma exposure. These findings underscore the importance of considering childhood traumatic experiences as a putative and potentially causative risk factor for psychotic experiences, as well as early prevention and intervention efforts targeting childhood adversity to reduce the risk of psychosis.

Trauma is prevalent amongst early psychosis patients and associated with adverse outcomes. Past trials of trauma-focused therapy have focused on chronic patients with psychosis/schizophrenia and comorbid Post-Traumatic Stress Disorder (PTSD). We aimed to determine the feasibility of a large-scale randomized controlled trial (RCT) of an Eye Movement Desensitization and Reprocessing for psychosis (EMDRp) intervention for early psychosis service users.

A single-blind RCT comparing 16 sessions of EMDRp + TAU v. TAU only was conducted. Participants completed baseline, 6-month and 12-month post-randomization assessments. EMDRp and trial assessments were delivered both in-person and remotely due to COVID-19 restrictions. Feasibility outcomes were recruitment and retention, therapy attendance/engagement, adherence to EMDRp treatment protocol, and the ‘promise of efficacy’ of EMDRp on relevant clinical outcomes.

Sixty participants (100% of the recruitment target) received TAU or EMDR + TAU. 83% completed at least one follow-up assessment, with 74% at 6-month and 70% at 12-month. 74% of EMDRp + TAU participants received at least eight therapy sessions and 97% rated therapy sessions demonstrated good treatment fidelity. At 6-month, there were signals of promise of efficacy of EMDRp + TAU v. TAU for total psychotic symptoms (PANSS), subjective recovery from psychosis, PTSD symptoms, depression, anxiety, and general health status. Signals of efficacy at 12-month were less pronounced but remained robust for PTSD symptoms and general health status.

The trial feasibility criteria were fully met, and EMDRp was associated with promising signals of efficacy on a range of valuable clinical outcomes. A larger-scale, multi-center trial of EMDRp is feasible and warranted.