The single most seductive claim in the whole psilocybin story is also the one most easily overstated. The idea that one or two sessions could produce relief from depression that lasts not days but months, even a year, breaks so cleanly from the daily-pill logic of conventional antidepressants that it is hard not to get swept up in it. But seductive claims are exactly the ones that need the hardest evidence, and durability is notoriously easy to assert and hard to prove. Most trials measure their main outcome at a few weeks and stop looking. The 2022 study led by Natalie Gukasyan, with Roland Griffiths and colleagues at Johns Hopkins, published in the Journal of Psychopharmacology, was built to keep looking, tracking the antidepressant effect of psilocybin out to a full year.
This article reads that follow-up carefully, because durability is arguably the question on which the entire clinical case for psilocybin turns. A drug that lifts depression for a fortnight and then fades would be a curiosity. A drug whose single-session benefit holds for a year would be something genuinely new in psychiatry. The Gukasyan study went after that question directly, and its answer was encouraging, though, as always, hedged by the limits that follow a small, self-selected, hard-to-follow sample over a long stretch of time. Check the specifics against the original paper before publishing, since the figures and follow-up details are where this story lives.
Why durability is the whole ballgame
To understand why a follow-up study deserves as much attention as the original trial it extends, you have to see what is special, and what is fragile, about the psilocybin claim. Conventional antidepressants work, when they work, by being taken every day. Stop the daily dose and the benefit typically fades, because the drug has to be present to do its job. The whole model is maintenance, a continuous chemical presence holding symptoms at bay. Psilocybin, by contrast, is given once or a few times and then cleared from the body within hours, and yet the early trials reported benefits lasting weeks or months afterward. That is a profoundly different shape of effect, and it is the heart of why the substance excited people. It suggested not maintenance but something closer to a reset, a single intervention that leaves the system in a better state rather than one that has to be continuously propped up.
But that exciting shape is exactly what is hardest to verify, and most vulnerable to wishful thinking. It is relatively easy to show that someone feels better a week after a powerful, meaningful experience. The harder question, the one that actually matters for whether this is a real treatment, is whether they still feel better many months later, long after the glow of the experience has faded and ordinary life has resumed its grind. Plenty of things can produce a short-lived lift that does not last. The durability claim is the one that, if true, would justify the whole enterprise, and it is the one that requires patiently following people over a long time to test, which is expensive, difficult, and far less glamorous than running the dosing sessions.
That is the gap the Gukasyan study was built to fill. It was not a fresh trial with new patients but a long-term follow-up of participants from a prior Johns Hopkins study, the randomized trial of psilocybin-assisted therapy for major depressive disorder that had reported strong results at shorter timepoints. The question it asked was simple to state and hard to answer. The benefit looked real at a few weeks. Was it still there a year on? That is the kind of unglamorous, essential work that turns a promising signal into something a field can actually rely on.
It helps to put the durability question in the context of what depression actually is, because that context is what gives the question its weight. Major depression, especially the treatment-resistant kind, tends to be a relapsing, recurring condition. People get better and then get worse again, cycle in and out of episodes, and a great deal of conventional treatment is really about managing that cycle over years rather than ending it. Against that backdrop, the ordinary expectation for any treatment is that its benefit will need maintaining, that without continued effort or medication the depression will tend to creep back. So the claim that a couple of psilocybin sessions could hold depression at bay for a year, with nothing in between, is not just a claim about one drug. It is a claim that cuts against the usual grain of how the illness behaves, which is precisely why it demands such careful, long-term evidence before anyone believes it.
There is a financial and practical dimension to the durability question too, easy to overlook but real. A treatment that works from two sessions and then lasts would be, despite the intensive and expensive nature of each session, potentially far more efficient over time than a lifetime of daily medication and ongoing care. But that entire economic case rests on the durability actually holding. If the benefit reliably faded after a few months and required repeated courses, the calculus would look very different, and the practical appeal of the approach would shrink considerably. So the year-long follow-up is not just scientifically important, it bears directly on whether the treatment could ever make sense as something health systems deliver at scale, which makes the patient work of measuring durability matter well beyond the laboratory.
What they actually did
The study followed participants from the earlier randomized trial of psilocybin for major depressive disorder, the one led by Alan Davis and colleagues that had found large, rapid antidepressant effects at its primary endpoints. Rather than starting over, Gukasyan and colleagues tracked those same participants forward in time, assessing their depression at extended intervals after treatment, out to twelve months. This continuation design is the right tool for the durability question, since it watches the same people across a long stretch rather than taking a single snapshot, letting the researchers see whether the early benefit held, faded, or vanished.
The original treatment those participants had received was the now-familiar package, two doses of psilocybin given within a structured program of psychological support, with preparation before the sessions and integration afterward, in a population diagnosed with major depressive disorder. The follow-up did not change that treatment. It simply measured what became of it over time, using established, validated depression rating scales administered at intervals stretching out to a year, so that the trajectory of each participant's depression could be charted across the months following their sessions.
The outcomes of interest were the standard markers clinicians use to judge whether a depression treatment is working and continuing to work. Response, meaning a substantial reduction in symptoms, and remission, meaning symptoms dropping below the threshold for clinical depression altogether, tracked at each follow-up point. By measuring response and remission rates at twelve months rather than at four weeks, the study could speak to the durability question in concrete clinical terms, not just whether average scores had drifted but whether people were actually still well by recognized standards a year after their treatment.
What they found
The result was encouraging, and it pointed where the enthusiasts had hoped. A substantial proportion of participants maintained their antidepressant response at the twelve-month follow-up. The benefit, in other words, did not simply evaporate once the acute experience receded. By the figures reported in the paper, a large share of participants, roughly half or more, still met criteria for response or remission at the one-year mark, a number worth verifying against the original but a striking one if it holds. People who had received two psilocybin sessions a year earlier were, many of them, still doing well by that point, which is exactly the durable, single-treatment effect the early excitement had promised but not yet proven.
That is a genuinely meaningful finding, because it speaks to the precise feature that makes psilocybin different. It is one thing to report that depression scores dropped at four weeks, which many treatments can manage. It is another to show that a meaningful fraction of people remained well a full year after a treatment they received only twice, with no maintenance dosing in between. If that pattern is real and holds up in larger studies, it points toward a kind of treatment psychiatry does not currently have, one that works from a brief intervention rather than continuous medication, and the Gukasyan follow-up was among the studies that put real long-term numbers behind that possibility rather than leaving it as a hopeful anecdote.
Pull quote: Two sessions, then nothing for a year, and a large share of people still well at the end of it. If that holds at scale, it is not a better antidepressant. It is a different kind of thing entirely.
It is worth being precise that durability was not universal. Not everyone who responded initially stayed well, and the study tracked the reality that some participants relapsed or saw their benefit fade over the year, which is honest and expected, since no treatment works permanently for everyone. But the headline was that a substantial group did maintain their gains, and that the average benefit across the sample persisted to a degree that short-term trials could not have revealed. The picture was not a miracle of universal lasting cure, but it was a real and clinically meaningful persistence of effect in a significant portion of the people treated, which is a more grounded and in some ways more believable result than a claim of uniform success would have been.
The pattern of who kept their benefit and who lost it is itself worth thinking about, even if a small study can only gesture at it. In depression generally, relapse is the rule rather than the exception, and a treatment that left even half of a treatment-resistant group well a year later would be doing markedly better than the usual course of the illness. So the fact that the benefit faded for some is not really evidence against the treatment, it is the normal texture of a chronic, relapsing condition, and the right comparison is not against perfection but against what would have happened anyway. Seen that way, a substantial maintained-response rate at twelve months is more impressive, not less, for being honest about the people it did not hold for. A result that admitted its own limits while still showing real persistence is exactly the kind of finding that ages well.
There is also a question the durability data raises without being able to answer, which is what maintaining benefit actually requires. Did the people who stayed well do so purely on the strength of two sessions a year earlier, or did some of them do ongoing work, in therapy, in their lives, in how they related to the experience they had, that helped the benefit stick? The integration framing that surrounds this treatment suggests the latter may matter, that the lasting effect might depend not only on the drug but on what a person does with the opening it creates. A follow-up study that simply measures outcomes cannot disentangle that, but it is a live and important question, because if maintaining benefit requires continued effort, then the picture of a one-and-done treatment is too simple, and the durable effect is really a collaboration between the session and everything that comes after it.
Why a follow-up like this is harder than it looks
It is worth appreciating the specific difficulty of what this study did, because long-term follow-ups are quietly among the hardest studies to run well, and their difficulty shapes how the results should be read. The central problem is attrition. Over a year, people drop out of contact with a study for all sorts of reasons, they move, they lose interest, they get busy, and sometimes, troublingly, the people who fare worst are the most likely to disappear. If the participants who relapsed are also the ones who stopped responding to follow-up, then the people who remain to be measured at twelve months are disproportionately the ones still doing well, which can make the durability look rosier than it really is. Managing and honestly reporting that attrition is a large part of what separates a trustworthy follow-up from a misleading one.
There is also the problem of disentangling the treatment from everything else that happens in a year of a person's life. A great deal occurs in twelve months, new relationships, job changes, other treatments, the natural ebb and flow of a mood disorder that waxes and wanes on its own. Attributing a person's wellbeing a year later specifically to two psilocybin sessions, rather than to all the other things that happened in between, is genuinely hard, and a follow-up study can only do so much to isolate the treatment's lasting contribution from the noise of a whole year of living. This is not a flaw in the Gukasyan study so much as an inherent limit of the question, but it means the durability finding has to be read as suggestive of a lasting effect rather than as clean proof that the psilocybin alone kept people well for a year.
These difficulties are exactly why long-term follow-ups are both essential and undervalued. They are less exciting than the original trial, harder to fund, more tedious to run, and beset by problems like attrition that the dosing sessions never face. But they answer the question that actually matters for a treatment, whether the benefit lasts, and a field that only ran short-term trials would never know whether its exciting early effects were durable or fleeting. The Gukasyan study did the patient, unglamorous work, and that work is part of why the durability claim rests on something more solid than hope.
Where the study holds up
The strengths here are real and specific to what a follow-up is for. The single greatest one is simply that it asked the durability question at all, and answered it with actual long-term data rather than speculation. Many fields are content to measure a short-term effect and assume, or hope, that it lasts. By tracking participants out to a year with validated measures, this study put concrete numbers on the persistence of the effect, which is exactly the evidence the durability claim had been missing. That alone makes it a valuable contribution regardless of the specific figures.
Reporting in terms of response and remission rates, rather than only average score changes, was another strength, since those clinical categories tell you whether people were actually well by recognized standards, not just whether a group mean had shifted. The continuity with a prior randomized trial meant the follow-up was extending a reasonably rigorous foundation rather than floating free. And the study, in keeping with the Hopkins group's broader practice, was candid about the limits and about the fact that not everyone maintained benefit, which is the kind of honesty that makes a durability claim trustworthy rather than promotional. A follow-up that admitted relapse and attrition while still finding meaningful persistence is more believable than one that reported uniform lasting success would have been.
Where it strains
The limits are substantial and mostly inherent to the design. The sample was small, carried over from a modest original trial, which means the durability figures, however encouraging, come from a limited number of people and cannot support confident generalization. The same selection issue that shaped the original trial shapes the follow-up, since these were people who volunteered for psilocybin treatment for their depression, an open and motivated group whose long-term course may not reflect that of a broader, less self-selected population. Whatever the one-year numbers show, they show it for this particular kind of participant.
Attrition, discussed above, is the sharpest specific worry. To the extent that people who fared worse were more likely to drop out of follow-up, the maintained-response figures could overstate the true durability, and any honest reading has to hold that possibility in view. The blinding problem from the original trial also echoes forward, since the initial benefit was measured in people who knew they had received psilocybin, and expectancy that inflated the early effect could carry some of its influence into the longer-term self-reports as well.
It is worth adding one more subtle limit that follow-up studies of this kind always carry, which is the absence of a comparison group over the long run. The original trial had a control condition, but by the time everyone has been treated and a year has passed, there is typically no untreated group still being tracked alongside the treated one. That means the durability is being read against an absolute standard, are these people still well, rather than against what a comparable untreated or differently treated group would have looked like at the same point. Without that long-run comparison, it is harder to say how much of the maintained benefit reflects the treatment specifically versus the natural course some of these people might have followed anyway. It is a structural feature of long-term follow-ups rather than a mistake, but it is one more reason the durability finding is best read as strongly suggestive rather than definitive.
The fundamental difficulty of attributing a year-later state to a treatment received a year earlier, rather than to everything else that happened in between, means the durability finding is best read as a strong suggestion of lasting effect rather than airtight proof of it. None of these undoes the result. They place it where it belongs, as encouraging long-term evidence from a small sample that needs replication at scale before the durability claim can be considered settled.
What it justifies, and what it does not
A measured reading is clear. What the Gukasyan 2022 study justifies is taking seriously the possibility that psilocybin's antidepressant effect can persist for up to a year after just two sessions in a substantial proportion of people, which is the durable, single-treatment shape that makes the substance genuinely distinctive. It justifies the larger, longer trials needed to confirm that durability in bigger and more representative samples, and it justifies treating the persistence of effect as a real phenomenon worth building on rather than a hopeful assumption. By putting concrete one-year numbers behind the durability claim, it moved that claim from anecdote toward evidence.
What it does not justify is treating the durability as proven or universal. The small, self-selected sample, the attrition risk, the echo of the blinding problem, and the inherent difficulty of attributing a year-later state to the treatment all keep the conclusion provisional. It does not justify the claim that psilocybin produces a lasting cure, since a substantial fraction of people did not maintain benefit and the figures come from a limited group. And it does not justify extrapolating from this supported clinical context to casual use, since the durable effect, to whatever extent it is real, was produced inside a structured therapeutic program. The study advanced the durability question meaningfully. It did not close it, and the larger follow-ups that could close it are exactly what the situation calls for.
Why this study matters
The Gukasyan 2022 study earns its place because it took on the question that the more glamorous trials tend to leave for later, and that matters most for whether psilocybin is a real treatment. Durability is the whole point of the psilocybin promise, the feature that distinguishes a brief intervention with a lasting effect from an ordinary drug that has to be taken forever, and a field that only measured short-term outcomes would be flying blind on exactly the thing that makes the approach exciting. By following participants out to a year and reporting honestly on who maintained benefit and who did not, this study put real evidence under a claim that had been carried, until then, largely by shorter-term data and hope.
It is also a quiet argument for the value of unglamorous science. Follow-up studies do not generate the headlines that the original trials do, they are harder to fund and more tedious to run, and they are beset by problems like attrition that the dosing sessions never face. But they answer the questions that actually determine whether a treatment is worth having, and the Gukasyan study is a reminder that the durability of an effect is not something you can assume, it is something you have to go and measure, patiently, over time. The honest way to hold the result is as encouraging, meaningful, and provisional, real long-term evidence that the effect can last for many people, paired with full awareness of the small sample and the attrition risk, and with the larger confirmatory follow-ups still to come. The promise of a lasting effect is the most important thing about psilocybin, and this is one of the studies that began to show it might actually be true.