What Does Definium's Trial Mean For Psychotherapy?

Background

Definium Therapeutics recently released compelling results from a large-scale Phase 3 clinical trial of DT120 ODT, an LSD-based tablet, for generalized anxiety disorder (GAD). They found that a single dose produced statistically significant reductions in anxiety compared with placebo, with improvements emerging as early as two days and remaining significant at 12 weeks, the study's primary endpoint.

Just a few months earlier, the company announced topline results from another Phase 3 trial investigating the same treatment in major depressive disorder (MDD). Those results were similarly promising, with a single administration producing significant reductions in depressive symptoms compared with placebo that were sustained through 12 weeks.

These findings add to a growing body of evidence suggesting that psychedelic compounds may produce substantial and sustained anxiolytic and antidepressant effects following just one or a small number of dosing sessions.

What surprised many therapists, myself included, was that there was no psychotherapy component included in this study.

Psychotherapy has historically played a prominent role in psychedelic treatment, with many contemporary protocols incorporating preparation, therapeutic support, and integration alongside administration of the psychedelic itself. Definium's model deliberately separates these components, investigating DT120 as a pharmacological treatment without adjunctive psychotherapy.

The finding that treatment with psychedelic compounds can produce significant reductions in both depression and anxiety without associated psychotherapy has challenged this idea that therapy is a quintessential part of psychedelic treatment. As psychedelic medicine becomes increasingly widespread, it raises an important question:

What role should psychotherapy play in psychedelic treatment?

I don't think these findings make psychotherapy irrelevant. Rather, I think they invite us to become more specific about what psychotherapy might contribute.

Demonstrating that a psychedelic can produce antidepressant or anxiolytic effects without formal psychotherapy is not the same as demonstrating that psychotherapy adds no benefit. In fact, Definium's findings raise another intriguing question: if meaningful clinical improvement can occur without formal psychotherapy, might outcomes be different, or even stronger, when psychotherapy is included?

Answering that question also requires us to consider what we mean by an outcome.

A person's lived experience is more than a score on a depression or anxiety scale. Two people could experience similar reductions in symptoms while having very different relationships with themselves, their emotions, their relationships, and their everyday lives.

This is where psychotherapy may have something different to offer. Psychotherapy can provide a space to explore what occurred during a psychedelic experience and what it might mean to the person who had it. That process might involve examining how someone relates to difficult thoughts and emotions, reconnecting with values, navigating relationships, recognizing longstanding behavioral patterns, or considering how insights from an experience might translate into everyday life.

These outcomes aren't necessarily captured by asking only how depressed or anxious someone feels.

I am also left wondering about participants who did not experience significant symptom improvement. So far, the question of psychotherapy’s added value has largely been framed around whether it might further enhance outcomes among those who already responded to the psychedelic intervention. But what about those who did not? Could therapeutic support before or during dosing have helped participants navigate challenging, confusing, or emotionally difficult experiences in ways that altered their eventual outcomes?

Similarly, might integration-focused psychotherapy after the experience have helped participants make sense of material that did not initially translate into symptom relief, potentially allowing therapeutic benefits to emerge over time? In this sense, psychotherapy may not simply amplify an existing psychedelic response; for some individuals, it could potentially influence whether that response becomes therapeutically meaningful at all. And this is where I think Definium's research opens an especially interesting door. If psychedelic treatment can produce clinical benefit without formal psychotherapy, future research can more directly investigate the added contribution of psychotherapy by comparing psychedelic treatment with and without a structured psychotherapeutic component.

Such research could help answer a more nuanced set of questions: Does psychotherapy further improve symptom reduction? Does it affect how long improvements last? Does it influence quality of life, functioning, psychological flexibility, relationships, or behavioral change? Are there certain people, or certain experiences, for whom psychotherapy is particularly valuable?

Perhaps the emerging question is not simply whether psychedelics need psychotherapy, but what psychotherapy contributes, for whom, and toward what kinds of change.

References

Definium Therapeutics. (2026, August 12). Definium Therapeutics announces positive topline results from Phase 3 Voyage study of DT120 ODT in generalized anxiety disorder. Definium Therapeutics. Definium Therapeutics. (2026, June 22). Definium Therapeutics announces positive topline results from Phase 3 Emerge study of DT120 orally disintegrating tablet (ODT) in major depressive disorder. Definium Therapeutics.