What Does the Research Say About Ketamine-Assisted Psychotherapy?

by | Jun 22, 2026 | Uncategorized

What Does the Research Say About Ketamine-Assisted Psychotherapy?

Over the past decade, ketamine has moved from the margins of psychiatric research to the centre of a growing conversation about how we treat depression, PTSD, and trauma. What was once known primarily as an anaesthetic — and, unfortunately, as a recreational drug — is now the subject of hundreds of published studies exploring its potential as a tool for psychological healing.

Until recently, most of that research focused on depression. But over the last two years, a new wave of trials has begun to look specifically at low-dose ketamine for trauma and PTSD — including, for the first time, low-dose oral ketamine and ketamine paired directly with trauma-focused therapies like EMDR and exposure work. This article reviews what the current evidence actually shows.

It is worth being clear at the outset about an important distinction: ketamine infusion (a medical model where the drug is administered without therapy) is not the same as ketamine-assisted psychotherapy (KAP), where ketamine is used at lower doses to facilitate deeper therapeutic work. The newest and most interesting trauma research sits at the intersection of the two.

What Is Ketamine-Assisted Psychotherapy (KAP)?

Ketamine-assisted psychotherapy integrates sub-anesthetic doses of ketamine with structured psychotherapy. Rather than using ketamine as a standalone pharmacological intervention, KAP treats the medicine as a facilitator of therapeutic processing — creating conditions in which the brain and nervous system are more receptive to change.

Within KAP, there are generally two dosing approaches:

  • Psycholytic (low dose): Lower, sub-psychedelic doses administered orally or sublingually. The person remains present, connected, and able to engage in conversation with the therapist. Psychological defences are gently softened, allowing access to emotions and memories that may be difficult to reach in ordinary states of consciousness.
  • Psychedelic (higher dose): Higher doses that induce a more fully altered or dissociative experience. The therapeutic work typically occurs before and after the session, rather than during it.

The psycholytic model is increasingly favoured by therapists who work with trauma and attachment, because the client can actively participate in the therapeutic process while the medicine is active. As we will see, this is also where the newest trauma research is concentrated.

The Research on Ketamine and Depression

Depression — particularly treatment-resistant depression (TRD) — is where the evidence for ketamine is strongest and longest-standing.

The landmark study by Zarate et al. (2006), published in the Archives of General Psychiatry, demonstrated that a single IV dose of ketamine (0.5 mg/kg) produced rapid antidepressant effects within hours — compared to the weeks typically required for conventional antidepressants. This finding opened an entirely new line of research into rapid-acting antidepressant mechanisms.

Since then, a large body of evidence has confirmed that ketamine produces rapid, if often time-limited, reductions in depressive symptoms. A recurring theme across this literature is that the antidepressant effect frequently fades within days to weeks unless it is reinforced — which is precisely the gap that combining ketamine with psychotherapy aims to address. The working premise of KAP is that therapy integrated with the medicine may produce more durable results than the medicine on its own.

The Research on Ketamine and PTSD and Trauma

The evidence for ketamine in the treatment of PTSD and trauma is newer than the depression literature — but it has grown substantially, and the most recent studies are encouraging.

The foundational PTSD trials

The first randomised controlled trial (RCT) of ketamine for chronic PTSD was published by Feder et al. (2014) in JAMA Psychiatry. In this crossover study of 41 mostly-civilian participants with chronic PTSD, a single IV infusion of ketamine (0.5 mg/kg) produced rapid reductions in PTSD symptoms 24 hours later, compared with the active placebo midazolam — with improvement across intrusion, avoidance, and hyperarousal symptoms.

The same group followed up with a 2021 RCT (Feder et al., 2021, American Journal of Psychiatry) testing repeated infusions — six over two weeks — in 30 people with chronic PTSD. Again, ketamine was significantly superior to midazolam, and crucially, repeated dosing helped sustain improvement for longer.

An important caveat: population matters

Not every trial has been positive. A large study by Abdallah et al. (2022) in a veteran and active-duty military population (158 participants) found that repeated IV ketamine did not significantly outperform placebo for PTSD. Researchers have proposed several explanations — veterans with PTSD may have lower treatment response generally, the military sample was predominantly male (versus the mostly-female civilian samples), and there were differences in dosing and methodology. The honest takeaway is that ketamine is not equally effective for everyone, and who benefits most is still being worked out.

The new frontier: low-dose oral ketamine for PTSD

Perhaps the most significant recent development for the low-dose approach is the OKTOP trial (Quigley et al., 2025), published in European Neuropsychopharmacology by researchers at the National PTSD Research Centre, University of the Sunshine Coast. This was the first open-label clinical trial of low-dose oral ketamine for PTSD — important because almost all prior research used IV infusions, which are costly and logistically demanding.

Twenty-two adults (aged 22–77, 55% female, 82% with comorbid depression) received once-weekly oral ketamine as a liquid drink, titrated from 0.5 mg/kg up to a maximum of 3.0 mg/kg, over six weeks. The results were striking:

  • Average PTSD symptom scores (PCL-5) fell from 40 at baseline to 17 immediately after treatment — below the clinical threshold for PTSD — and remained reduced (21) one month later, with no further ketamine.
  • 73% of participants responded (a ≥50% reduction in symptoms) right after treatment, and 59% maintained that response one month later.
  • Participants also reported significant improvements in depression, anxiety, stress, suicidality, sleep, social and occupational functioning, and overall wellbeing.
  • The treatment was well tolerated, with no serious adverse events and mostly mild, short-lived dissociation — no one withdrew due to side effects.

The authors noted these outcomes are comparable to IV ketamine trials for PTSD, suggesting low-dose oral administration is a feasible, tolerable, and more accessible route worth studying further. As an open-label pilot without a control group, it cannot prove cause and effect on its own — but as a signal for the low-dose model, it is genuinely promising.

Combining Low-Dose Ketamine With Trauma-Focused Therapy

The most exciting shift in this field is the move from “ketamine or therapy” to “ketamine plus therapy” — using the medicine to open a window in which trauma processing can go deeper. Several recent studies test exactly this:

  • Ketamine-assisted EMDR (Topel & Ciccone, 2025), European Journal of Psychotraumatology: This pilot study paired low-dose sublingual ketamine with the standard 8-phase EMDR protocol, with the client self-administering the medicine at a strategically timed point during reprocessing. The psycholytic dose is intended to expand the window of tolerance and enhance neuroplasticity while preserving the client’s ability to engage in bilateral stimulation and verbal processing. The study reported statistically and clinically significant reductions in PTSD symptoms and functional impairment.
  • Ketamine plus Written Exposure Therapy (Feder et al., 2025), Journal of Clinical Psychiatry: Here, brief structured exposure therapy was interleaved with the final ketamine infusions specifically to take advantage of the ketamine-induced neuroplasticity window. The combination produced meaningful, and more durable, symptom reductions.
  • Ongoing intensive protocols: Research teams (including at Yale) are now running week-long intensive trials combining low-dose ketamine infusions (0.2–0.5 mg/kg) with intensive prolonged exposure therapy, aiming to compress months of trauma work into days by treating during the plasticity window. These trials are underway, with results still to come.

The common thread is timing: ketamine appears to create a period of enhanced neuroplasticity, and what happens during that period — the actual therapeutic work — may determine whether the gains last.

The Neuroplasticity Window: Why Therapy Matters

One of the most significant developments in this field is the growing understanding of why ketamine may enhance therapy at a neurological level.

Ketamine acts primarily as an NMDA receptor antagonist, which triggers a cascade of effects including increased glutamate signalling and the release of BDNF (brain-derived neurotrophic factor) — a protein that supports the growth, survival, and connection of neurons. This creates what researchers describe as a “window of neuroplasticity”: a period during and after ketamine administration when the brain is temporarily more capable of rewiring patterns that may have been rigid for years.

Neuroimaging gives this idea support. A functional MRI study of participants from the Feder trials found that ketamine strengthened connectivity between the amygdala (the brain’s threat detector) and the ventromedial prefrontal cortex (involved in regulating fear), and that this change was associated with PTSD improvement — overlapping with the very circuits implicated in fear extinction. In plain terms: ketamine may temporarily make it easier for the brain to learn that a once-threatening memory is no longer dangerous.

The REBUS model (Relaxed Beliefs Under Psychedelics; Carhart-Harris & Friston, 2019) offers a complementary psychological framework. It proposes that substances like ketamine temporarily relax the confidence the brain places on deeply held beliefs — including negative self-beliefs like “I’m not enough” or “I’m fundamentally broken.” For clients carrying early relational trauma, emotional neglect, or attachment wounds, these rigid beliefs are often the core of what keeps them stuck. The neuroplasticity window does not heal the trauma by itself — but it may create the conditions in which approaches like EMDR, IFS, or somatic processing can reach deeper and produce more lasting change.

Psycholytic vs. Psychedelic Dosing: What Does the Research Suggest?

The psycholytic (low-dose) approach has a long, if neglected, history. A 2022 review in Frontiers in Psychiatry (Passie et al.) traced lower-dose psycholytic therapy back to mid-twentieth-century European clinics, where naturalistic follow-up studies of treatment-refractory patients reported success rates above 66% — results that were never confirmed in controlled trials because the field was abandoned in the late 1960s. Today’s low-dose ketamine work is, in many ways, a rigorous revival of that approach.

The psycholytic model has several characteristics that make it particularly relevant for trauma-focused therapeutic work:

  • The client remains present and able to engage in relational, verbal therapy during the session.
  • The therapist can guide processing in real time — working with what arises, rather than only preparing for and debriefing after the experience.
  • The gentler alteration in consciousness may be more appropriate for clients with trauma histories, dissociation, or nervous system sensitivity.
  • Oral and sublingual routes are more cost-effective and logistically accessible than high-dose models requiring extensive monitoring — as the OKTOP oral trial demonstrated.

Large-scale, controlled trials of psycholytic dosing specifically are still limited — but the clinical rationale is now backed by converging evidence from neuroplasticity research, the REBUS framework, the OKTOP oral trial, and early therapy-combination pilots like ketamine-assisted EMDR.

Limitations of the Current Research

It is important to be transparent about what we don’t yet know:

  • Small sample sizes: Many KAP and low-dose trauma studies involve fewer than 50 participants, making it difficult to generalise findings.
  • Few controlled trials: Several of the most encouraging trauma studies — including the OKTOP oral trial and the ketamine-assisted EMDR pilot — are open-label, without a placebo group. This makes it hard to separate the effect of ketamine from therapy, expectation, and placebo.
  • Methodological variability: There is no standardised KAP protocol. Studies differ in dose, route, number of sessions, and type of therapy integrated.
  • Population differences: As the veteran/military trials show, results that hold in one group may not transfer to another.
  • Limited long-term data: Most studies measure outcomes over weeks to a few months. We do not yet have a clear picture of how long benefits last or what maintenance should look like.

This does not mean the treatment is ineffective. It means the evidence is promising but still emerging, and larger, controlled trials are needed — particularly ones that compare ketamine-plus-therapy against ketamine alone and against established trauma treatments like EMDR and prolonged exposure.

What This Means for People Considering This Approach

If you are exploring whether ketamine-assisted psychotherapy might be relevant to your situation, the research suggests several things worth knowing:

  • Ketamine is not a cure. It is a tool that may create conditions for deeper therapeutic work.
  • The combination of ketamine with psychotherapy appears to produce better and more sustained results than ketamine alone.
  • New low-dose and oral approaches are expanding access, and early PTSD results are comparable to older IV trials.
  • The psycholytic (low-dose) approach allows you to remain present and actively engage in the therapeutic process — which can matter a great deal for trauma and dissociation.
  • The strongest evidence still exists for treatment-resistant depression; trauma and PTSD evidence is growing quickly but remains earlier-stage.
  • This approach is not appropriate for everyone. Careful medical screening and a strong therapeutic relationship are essential foundations.

As with any therapeutic approach, the quality of the therapeutic relationship and the skill of the clinician matter as much as — if not more than — the specific tool being used.

Valentina Chichiniova, RCC is a Registered Clinical Counsellor at Emergence Counselling & Wellness in Vancouver, BC. She specializes in complex trauma, EMDR, Deep Brain Reorienting, and psychedelic-assisted psychotherapy. Valentina offers online therapy for clients across British Columbia.

Book a free consultation | Learn more about Valentina

References:

  • Zarate, C. A., et al. (2006). A randomized trial of an N-methyl-D-aspartate antagonist in treatment-resistant major depression. Archives of General Psychiatry, 63(8), 856–864.
  • Feder, A., et al. (2014). Efficacy of intravenous ketamine for treatment of chronic posttraumatic stress disorder: A randomized clinical trial. JAMA Psychiatry, 71(6), 681–688.
  • Feder, A., et al. (2021). A randomized controlled trial of repeated ketamine administration for chronic posttraumatic stress disorder. American Journal of Psychiatry, 178(2), 193–202.
  • Abdallah, C. G., et al. (2022). Repeated ketamine infusions for chronic PTSD in a veteran and active-duty military population: A randomized controlled trial.
  • Quigley, B. L., et al. (2025). Low dose oral ketamine treatment on post-traumatic stress disorder (PTSD) (OKTOP): An open-label pilot study. European Neuropsychopharmacology. https://doi.org/10.1016/j.euroneuro.2025.01.003
  • Topel, S., & Ciccone, T. (2025). Ketamine-assisted EMDR for PTSD: A pilot study. European Journal of Psychotraumatology.
  • Feder, A., et al. (2025). Adding Written Exposure Therapy to ketamine treatment for chronic PTSD. Journal of Clinical Psychiatry, 86(2), 24m15622.
  • Passie, T., et al. (2022). Lower-dose psycholytic therapy – A neglected approach. Frontiers in Psychiatry, 13, 1020505.
  • Carhart-Harris, R. L., & Friston, K. J. (2019). REBUS and the anarchic brain: Toward a unified model of the brain action of psychedelics. Pharmacological Reviews, 71(3), 316–344.
  • Dore, J., et al. (2019). Ketamine assisted psychotherapy (KAP): Patient demographics, clinical data and outcomes in three large practices administering ketamine with psychotherapy. Journal of Psychoactive Drugs, 51(2), 189–198.
  • van der Kolk, B. (2014). The Body Keeps the Score: Brain, Mind, and Body in the Healing of Trauma. Viking.

This is educational content based on published clinical research. It is not medical advice, a recommendation for any specific treatment, or a substitute for professional clinical consultation.