The trial enrolled 60 participants who were experiencing a current major depressive episode accompanied by clinically significant anhedonia, a symptom domain that has long frustrated psychiatrists. Anhedonia, which involves diminished interest, motivation, and capacity for pleasure, is common in depression, often persists even when other symptoms improve, and is strongly linked to dysfunction in the brain’s reward circuitry. Standard antidepressants such as selective serotonin reuptake inhibitors frequently leave this dimension untouched, which is why the field has been searching for treatments that target reward processing directly rather than mood in general. The researchers designed the study as an experimental medicine trial, a design that uses a neurobiological measure as the primary endpoint to test whether a drug engages its intended brain circuit before committing to larger efficacy trials.

Participants were randomized one to one to receive either azetukalner at a dose of 20 milligrams taken orally once daily with food, or a matching placebo, for eight weeks. The primary endpoint was the change in activity of the bilateral ventral striatum, a key hub of the brain’s reward system, measured with functional magnetic resonance imaging while participants performed a reward task, comparing scans taken at baseline with those taken at week eight. The ventral striatum, which includes the nucleus accumbens, responds robustly to the anticipation and receipt of rewards, and blunted activation in this region has been repeatedly observed in depressed patients, particularly those with prominent anhedonia. The logic of the trial was straightforward: if azetukalner truly modulates reward circuitry, eight weeks of treatment should measurably strengthen the ventral striatum’s response to anticipated rewards.

That primary hypothesis was not borne out. The researchers found no significant difference in the ventral striatum response to reward anticipation between the azetukalner group, which comprised 29 participants, and the placebo group, which comprised 31. In the world of clinical neuroscience, this kind of negative primary endpoint is not unusual, and the authors were careful to report it plainly. Functional MRI measures are noisy, sample sizes in experimental medicine studies are typically modest, and the link between a drug’s molecular mechanism and a hemodynamic imaging signal involves many layers of biology that can dilute an effect. Still, the result means that the most direct test of the drug’s proposed mechanism of action in this study did not find the expected neural signature.

The secondary outcomes told a more encouraging story. Compared with placebo, azetukalner was associated with numerical benefit on the Montgomery-Åsberg Depression Rating Scale, a clinician-administered measure of depression severity, and on the Snaith-Hamilton Pleasure Scale, a widely used self-report instrument for anhedonia. Neither difference reached statistical significance, a critical caveat, but the direction of the effects was consistent with a genuine signal. Perhaps more telling, most of the exploratory endpoints in the trial also numerically favored azetukalner over placebo. When a drug shows a consistent directional trend across many independent measures, even without statistical significance, it can suggest that a real effect exists but that the study was underpowered to detect it, though it can also reflect chance, and the authors acknowledged this ambiguity.

Safety results were a clear positive. Discontinuation rates due to adverse events were low and did not differ between the azetukalner and placebo groups, an important finding for a medication that would need to be taken chronically if it ever reaches the clinic. Kv7 channel openers, which include the anticonvulsant ezogabine that preceded azetukalner in experimental psychiatry research, have generally shown tolerable side effect profiles at the doses used in neuropsychiatric studies. The favorable tolerability observed here matters because depression is a chronic, relapsing condition, and any future treatment must be something patients can sustain over months or years without burdensome side effects driving them off the drug.

The biology behind the approach is worth understanding. Kv7 channels, encoded by the KCNQ gene family, are voltage-gated potassium channels that act as molecular brakes on neuronal firing. By regulating the flow of potassium ions out of neurons, they help stabilize the membrane potential and control how easily a cell fires an action potential. A positive allosteric modulator like azetukalner does not block or activate the channel directly at its main gate; instead, it binds to a site away from the pore and makes the channel easier to open, thereby dampening neuronal excitability. In reward circuits, this dampening is thought to reduce the excessive phasic activity of neurons that project to the ventral striatum, which some theories link to the blunted, dysregulated reward processing seen in depression and anhedonia. Preclinical work and earlier small human studies of ezogabine suggested that enhancing Kv7 activity could normalize reward circuit function, motivating the development of azetukalner as a more refined candidate.

The experimental medicine framework itself is a notable feature of the study. Rather than measuring only symptom scores, the trial put a mechanistic biomarker, reward-related ventral striatum activation, at the center of the design, funded in part by the National Institute of Mental Health under an award supporting this translational strategy. The idea is that demonstrating target engagement in the brain early in development can guide decisions about whether to advance a compound to larger and far more expensive efficacy trials. In this case, the biomarker result argues for caution, while the clinical signal argues for continued interest. The study was registered at ClinicalTrials.gov under identifier NCT04827901, and the investigational product and matching placebo were provided by Xenon Pharmaceuticals under a research agreement with the Icahn School of Medicine at Mount Sinai.

For patients and clinicians, the practical takeaway is that azetukalner remains an unproven but scientifically interesting candidate. The trial was small, with 60 participants, and its primary purpose was to test mechanism rather than to win regulatory approval, so neither a positive nor a negative primary endpoint would have been definitive about clinical efficacy. The consistent numerical trends on depression severity and anhedonia measures, combined with good tolerability, give the researchers grounds to argue that larger trials with adequate statistical power are warranted. At the same time, the failure to shift the ventral striatum imaging signal raises real questions about whether the drug, at this dose and duration, engages the reward circuitry in the way the hypothesis predicted, or whether fMRI measures of reward anticipation are simply too insensitive to capture the effect.

The broader significance of the study lies in what it says about the future of antidepressant development. Depression remains one of the most common and debilitating diseases worldwide, and a substantial fraction of patients do not respond adequately to existing medications, which mostly act on monoamine neurotransmitter systems discovered decades ago. Novel targets such as the Kv7 potassium channels, glutamatergic agents, and psychedelic compounds are all being tested in parallel, reflecting a field-wide effort to find treatments that work through fundamentally different biology. This trial, led by senior author James W. Murrough and first author Rachel Fremont, exemplifies the careful, mechanistically grounded path that new candidates must travel: a clear molecular hypothesis, a measurable brain endpoint, honest reporting of a negative primary result, and a transparent account of the suggestive but unproven clinical signals that remain. Whether azetukalner ultimately helps people with depression and anhedonia will depend on the larger studies that this work now makes easier to design.

Subject of Research: A randomized controlled trial of the Kv7 channel opener azetukalner in major depressive disorder with anhedonia

Article Title: A randomized, controlled experimental medicine study of the novel Kv7 channel opener azetukalner in individuals with major depressive disorder and anhedonia

Article References: Fremont, R., Neukam, P. T., Govindarajulu, U. S., Ables, J. L., Hameed, S., Corwin, M., Hargrove, M. B., Chang, H. L., Boukezzi, S., Kelly, C. A., Swann, A., Salas, R., Amarneh, D., Engelhardt, J., Weyland, A., Bagiella, E., Morris, L., Mathew, S. J., & Murrough, J. W. (2026). A randomized, controlled experimental medicine study of the novel Kv7 channel opener azetukalner in individuals with major depressive disorder and anhedonia. Translational Psychiatry. https://doi.org/10.1038/s41398-026-04431-6

Image Credits: AI Generated

DOI: 10.1038/s41398-026-04431-6

Keywords: azetukalner, Kv7 channels, major depressive disorder, anhedonia, ventral striatum, functional MRI, reward processing, clinical trial, translational psychiatry, potassium channels, antidepressant development, Xenon Pharmaceuticals

The perspective, authored by Mehmet Kosa of Marshall University, Nora M. Barnes-Horowitz of the University of Colorado Boulder, and Michelle G. Craske of the University of California, Los Angeles, builds on a growing body of evidence that treatments specifically targeting reward sensitivity can meaningfully reduce anhedonia. Rather than treating low mood as a single undifferentiated problem, the authors argue that clinicians should think of anhedonia as a disorder of the reward system, one that can be systematically probed and retrained. Virtual reality, they contend, offers an unprecedented medium for doing exactly that, because it can deliver experiences that are specific, fine-tuned, immersive and personalized in ways that traditional talk therapy or flat-screen interventions cannot match.

The theoretical foundation of the proposal rests on decades of work dissecting how the brain processes reward. Neuroscientists have long distinguished between separable components of reward: ‘liking’, the hedonic pleasure experienced in the moment; ‘wanting’, the motivational drive that pushes an organism to seek out rewards; and learning, the process by which the brain updates its expectations about what is worth pursuing. These components rely on partially distinct neural circuits, and they can be impaired independently of one another. A person with anhedonia may be able to enjoy a pleasurable experience once they are fully engaged in it, yet lack the motivation to begin it, or they may fail to learn from positive outcomes that would normally encourage repetition. This fractionation matters clinically, because a treatment that boosts one component may do nothing for another.

At the heart of the new argument is a deceptively simple computational concept: the reward prediction error. When an outcome turns out better than expected, dopamine neurons in the ventral striatum and midbrain fire in a characteristic burst, signaling a positive prediction error. This signal is not merely a marker of pleasure; it is the engine of reinforcement learning, teaching the brain which actions and contexts are worth repeating. Decades of research, from classic animal studies to modern human neuroimaging, have established that these prediction error signals drive learning, memory encoding, attention and motivation. Crucially, work by Wolfram Schultz and others has shown that the magnitude of the dopamine response scales with the discrepancy between expected and obtained reward, not with the reward itself.

What makes this relevant to anhedonia is a growing literature suggesting that prediction error signaling is blunted in people with the symptom. Studies of reinforcement learning in depression have found flattened responses to unexpected rewards, and related work on internet gaming disorder has documented dampened prediction error signals as well. Meanwhile, computational models of momentary well-being, developed by Robb Rutledge and colleagues, indicate that fleeting happiness depends more on recent prediction errors than on the absolute size of rewards received. In other words, the emotional lift we feel in daily life may be driven less by what we get and more by how much better it was than we anticipated. If anhedonic individuals experience smaller positive prediction errors, the world may feel flat not because nothing good happens, but because nothing good surprises them.

This is where virtual reality enters the picture. The authors propose that carefully engineered VR interactions could be designed specifically to generate positive reward prediction errors, delivering outcomes that reliably and pleasantly exceed expectations. Unlike real life, where reward statistics are messy and uncontrollable, a virtual environment gives designers precise control over timing, probability, magnitude and surprise. A user might reach for a glowing object expecting a modest sparkle and instead trigger a cascading burst of color, sound and narrative payoff. Each such moment, the argument goes, delivers a clean, well-timed dopaminergic teaching signal to a reward system that has grown underresponsive. Over repeated exposures, these signals could gradually recalibrate reward sensitivity, strengthening the learning and motivational components of reward processing that are most impaired in anhedonia.

The second pillar of the proposal is equally ambitious: rather than treating VR as a single undifferentiated pleasure machine, the authors argue that distinct activities within a virtual experience should be mapped onto the distinct phases of reward processing. Anticipatory reward, the ‘wanting’ phase, could be targeted with activities that build expectation and motivation, such as quests, exploration and goal pursuit that require effortful engagement before any payoff arrives. Consummatory reward, the ‘liking’ phase, could be targeted with immersive savoring experiences, rich sensory environments and moments designed purely for in-the-moment enjoyment. Reward learning, meanwhile, could be targeted with probabilistic tasks and feedback structures that require the user to discover, through trial and error, which choices lead to better outcomes. This phase-specific design philosophy mirrors the structure of Positive Affect Treatment, the neuroscience-informed psychotherapy developed by Craske and colleagues, which has shown in multiple randomized controlled trials that directly targeting reward sensitivity can reduce anhedonia, depression and anxiety symptoms.

The evidence base for this approach is still young but encouraging. A pilot study of VR-based reward training for anhedonia demonstrated feasibility, and randomized trials of virtual reality-enhanced behavioral activation for major depressive disorder have shown promising results. Meta-analyses of VR exposure therapy for anxiety disorders have established that immersive technologies can produce clinically meaningful change, and systematic reviews of positive mood induction confirm that virtual environments can reliably elicit positive emotions. Research on presence, the subjective sense of ‘being there’ in a virtual world, suggests that immersion amplifies emotional responses, and studies of interactive media indicate that agency, the feeling that one’s actions matter, adds further emotional impact on top of immersion alone. Interactivity, the authors emphasize, is not a cosmetic feature: it is what allows the user to generate their own prediction errors through action, rather than passively receiving them.

The perspective also confronts the practical and ethical challenges honestly. VR sickness remains a barrier for some users, and validated questionnaires now exist to monitor it. Privacy and security concerns in immersive platforms are real, since these systems can collect intimate behavioral and physiological data. Ethical questions about children and adolescents, and about the risk that highly rewarding virtual experiences could shade into problematic use, particularly given what is known about gaming disorder, must be taken seriously. The authors call for adaptive designs that personalize difficulty and reward statistics to each user, rigorous measurement of presence and side effects, and careful attention to who benefits and who might be harmed.

If the vision succeeds, the implications could extend well beyond anhedonia. Objective measures of reward sensitivity are already being used to track treatment response, and neuroimaging work has linked ventral striatal reward activation to lasting improvements in life satisfaction. A VR platform that reliably elicits positive prediction errors and targets each reward phase could serve simultaneously as a clinical intervention, a research instrument and a personalized medicine tool, allowing clinicians to identify which component of reward processing is impaired in a given patient and to tune the virtual experience accordingly. The authors frame their contribution as a roadmap rather than a finished treatment, but the destination is clear: a future in which the brain’s pleasure circuits, dulled by illness, can be systematically and safely reawakened, one well-timed surprise at a time, inside a headset.

Subject of Research: Using interactive virtual reality to generate reward prediction errors and target anticipatory, consummatory and learning reward phases as a treatment approach for anhedonia.

Article Title: Reward prediction error and reward components in interactive virtual reality for anhedonia

Article References: Kosa, M., Barnes-Horowitz, N. M., & Craske, M. G. (2026). Reward prediction error and reward components in interactive virtual reality for anhedonia. Nature Mental Health. https://doi.org/10.1038/s44220-026-00731-4

Image Credits: AI Generated

DOI: 10.1038/s44220-026-00731-4

Keywords: anhedonia, virtual reality, reward prediction error, dopamine, reward sensitivity, positive affect treatment, reinforcement learning, ventral striatum, behavioral activation, mental health, immersive technology, depression