The Induction of Dissociative States: A Meta-Analysis.
Benjamin Brake, Lillian Wieder, Natasha Hughes, Ivonne Saravia Lalinde, Danielle Marr, Dali Geagea, Susannah Pick, Antje A. T. S. Reinders, Sunjeev K. Kamboj, Trevor Thompson, Devin B. Terhune
Biological Psychiatry Global Open Science July 1, 2025 DOI: 10.1016/j.bpsgos.2025.100521 (opens in new tab)
Study at a glance
AI-extracted from the abstract| Characteristics | Meta-analysis Peer reviewed |
|---|---|
| Sample size | 6,692 |
| Population | Individuals from clinical and nonclinical samples |
| Interventions | mirror gazing ketamine cannabis |
| Topics | Altered states of consciousness Ketamine PTSD |
| Keywords | Mirror gazing Nmdar Psychedelics Dissociative induction Dissociation induction Dissociative states Evoked dissociation Dissociative experiences Drug-induced dissociation Psychopharmacology Neuropharmacology Chemical induction Drug effects Pharmacological agents Induction techniques Experimental methods Evocation techniques Non-pharmacological induction Behavioral techniques Research approaches |
| Citations | 5 |
| Key findings | Mirror gazing and pharmacological agents, especially ketamine and cannabis, induced state dissociation levels comparable to or exceeding those in PTSD dissociative and complex subtypes. |
Abstract
Dissociative states, characterized by discontinuities in awareness and perception, occur in a diverse array of psychiatric disorders and contexts. These states have been experimentally modeled in the laboratory through various induction methods, but relatively little is known about the efficacy and comparability of different experimental methods. In this meta-analysis, we quantified dissociative states, as indexed by a standardized instrument (Clinician-Administered Dissociative States Scale), at baseline in varied diagnostic categories and in response to different experimental induction methods (psychological techniques and pharmacological agents) in both clinical and nonclinical samples. Primary outcomes were state dissociation effect sizes (Hedges' g) (PROSPERO registration: CRD42022384886). A total of 2214 articles were screened, which yielded 123 eligible articles and 155 effect sizes comprising 6692 individuals. High levels of baseline state dissociation were observed in multiple diagnostic categories relative to controls, with the largest effects found in the dissociative and complex subtypes of posttraumatic stress disorder (PTSD-DC). In controlled experiments, induced state dissociation was most pronounced in response to mirror gazing and multiple pharmacological agents, with effects in ketamine and cannabis exceeding baseline state dissociation in PTSD-DC. The effect sizes were characterized by pronounced heterogeneity but were not reliably associated with methodological features of the original studies. Elevated state dissociation is present in multiple diagnostic categories, and comparable or higher levels can be reliably induced in controlled experiments using psychological techniques and pharmacological agents. These results demonstrate the efficacy of several methods for experimentally modeling dissociation and have implications for measuring adverse events and predicting outcomes in clinical interventions that involve pharmacological agents.
Comparable studies
Other systematic reviews and meta-analyses on ketamine for PTSD, most cited first.
| Study | Year | Design | Participants |
|---|---|---|---|
| Efficacy of Psychoactive Drugs for the Treatment of Posttraumatic Stress Disorder: A Systematic Review of MDMA, Ketamine, LSD and Psilocybin Adults with PTSD | 2020 | Systematic review | n = 9 |
| The Multivariate Effect of Ketamine on PTSD: Systematic Review and Meta-Analysis Soldiers with combat experience, including wounded or burn soldiers | 2022 | Meta-analysis | n = 503 |
| Effectiveness of Ketamine for the Treatment of Post-Traumatic Stress Disorder - A Systematic Review and Meta-Analysis. Adults with post-traumatic stress disorder | 2024 | Systematic review and meta-analysis | |
| Molecular pathways of ketamine: A systematic review of immediate and sustained effects on PTSD. | 2025 | Systematic review | |
| Ketamine in the effective management of chronic pain, depression, and posttraumatic stress disorder for Veterans: A meta-analysis and systematic review. Military populations (active-duty and Veterans) | 2024 | Meta-analysis and systematic review |
Citations in the library
Cited by 3
- Task-induced transient depersonalization- and derealization-like experiences: a comparative examination of mirror gazing and fixed attention tasks Consciousness and Cognition July 3, 2026
- Development and validation of a short-form (6-item) version of the clinician-administered dissociative states scale (CADSS-SF). European Journal of Psychotraumatology June 15, 2026
- Toward an Experimental Model to Study Dissociation in the Laboratory: Current Challenges and a Path Forward Biological Psychiatry Global Open Science June 1, 2025
Cites 19
- Measurement of dissociative states with the Clinician‐Administered Dissociative States Scale (CADSS) Journal of Traumatic Stress 1998
- Side-effects associated with ketamine use in depression: a systematic review. The Lancet Psychiatry 2018
- Features of Dissociation Differentially Predict Antidepressant Response to Ketamine in Treatment-Resistant Depression Journal of Affective Disorders February 17, 2018
- Ketamine and serotonergic psychedelics: An update on the mechanisms and biosignatures underlying rapid-acting antidepressant treatment Neuropharmacology January 13, 2023
- Classical and non-classical psychedelic drugs induce common network changes in human cortex. Neuroimage June 1, 2023
and 14 more in the library