Almost all behavioral-health coverage, including this desk’s, divides into two subjects: drugs and software. Running alongside both is a third axis that rarely gets treated as a category at all, the bioelectronic devices that modulate the brain directly. Over recent months the signals accumulated one at a time, a vagus nerve stimulation pivotal trial, deep brain stimulation programs, a non-invasive deep-stimulation technique, each covered, if at all, as a standalone gadget. Assembled into a category, they form a real and growing segment of behavioral-health treatment with a clear structure, a clear commercial gate, and a single defining obstacle that every modality in it runs into.
The spectrum
The category spans from established to frontier, and the three points on that spectrum tell the whole story.
At the established end is vagus nerve stimulation. LivaNova’s VNS Therapy, an implanted device that stimulates the vagus nerve, has been FDA-approved as an adjunctive treatment for treatment-resistant depression since 2005. Its problem has never been approval. It has been evidence and reimbursement. The RECOVER trial, a large sham-controlled randomized study designed in partnership with the Centers for Medicare and Medicaid Services to generate the data for broad Medicare coverage, missed its primary endpoint because of an unexpectedly strong response in the sham group, even as the active arm improved meaningfully from baseline and several secondary endpoints separated. LivaNova has since moved to ask CMS to reconsider national coverage. Twenty years after approval, the gate is still a payer and a sham control, not the FDA.
In the high-promise, trial-troubled middle is deep brain stimulation. Implanted electrodes target mood circuits such as the subcallosal cingulate or the ventral capsule and ventral striatum, and open-label series have reported striking results, with a large share of patients improving by at least half over a period of years. But the pivotal sham-controlled trials have repeatedly failed to separate active stimulation from sham. The field’s answer is the closed-loop turn: rather than delivering fixed, continuous stimulation, newer systems sense a neural biomarker of the patient’s mood state and stimulate in response. A 2021 case report of biomarker-driven closed-loop stimulation for treatment-resistant depression produced a dramatic individual result, and Abbott’s TRANSCEND study, running under an FDA Breakthrough Device designation, is now testing deep brain stimulation for treatment-resistant depression in a pivotal randomized trial. Closed-loop approaches are also being tested in bipolar depression, and the technique already holds a humanitarian device exemption for severe OCD.
At the frontier is temporal interference stimulation. It is a non-invasive technique that uses two or more high-frequency electric fields delivered from scalp electrodes, tuned so that they interfere at a chosen depth, allowing stimulation of deep brain targets without surgery and without strongly activating the cortex above them. Early Phase 1 clinical trials in psychiatric disorders and in memory are now recruiting. If temporal interference delivers on its premise, it offers something the category has never had: the depth of deep brain stimulation without the implant.
The obstacle they share
The reason to look at these modalities together is that they fail and succeed in the same way. Each one tends to look good in open-label use, where everyone knows the device is on, and each one struggles in blinded, sham-controlled trials. RECOVER’s sham response is the latest instance, and the history of deep brain stimulation in depression is a series of open-label successes that did not survive sham-controlled testing.
This is the device version of a problem the desk has tracked repeatedly on the drug side: the functional-unblinding and placebo-response problem that plagues psychedelic trials. The mechanism is the same. A brain-stimulation intervention is perceptible, the expectation of benefit is powerful, the patients are severely ill and highly motivated, and the sham arm consequently responds strongly. It is not a coincidence that recurs across VNS and DBS. It is the structural challenge of the entire category, and any honest assessment of bioelectronic psychiatry has to start from it.
The strategic response
The most important shift in the field is the move toward closed-loop, biomarker-driven stimulation, and it is a direct response to the sham problem. The bet is that a system which senses an objective neural signature of the disorder and triggers stimulation in response can produce an effect robust and specific enough to separate from sham, where fixed open-loop stimulation has not. This connects the device category to the broader biomarker push the desk has followed elsewhere, the search for objective measures of target engagement, from circuit signatures to EEG endpoints. Closed-loop neuromodulation is the same idea expressed in hardware: stimulate in response to the brain rather than at it. It is early, resting on single cases and small trials, but it is unmistakably where the science is heading.
The commercial read
For an audience tracking behavioral health as an industry, three points matter. The gate is reimbursement and evidence, not approval, and VNS is the cautionary template: a therapy approved for two decades still fighting for Medicare coverage on the strength of a sham-controlled trial. Device makers here, LivaNova, Abbott, Medtronic, NeuroPace, face a payer-and-evidence bottleneck rather than a regulatory one. The addressable population is real and underserved, since 30 to 40 percent of major depression is treatment-resistant and the device modalities target precisely the patients that drugs have failed. And this is a medtech segment, not a pharmaceutical one, with different players, different economics built on implants and procedures rather than prescriptions, and a different reimbursement logic. It deserves to be tracked on its own terms.
The caveats
None of this is an imminent breakout. The sham problem is unsolved and may be structural rather than fixable. Closed-loop stimulation is promising but unproven at any scale. Deep brain stimulation requires neurosurgery, which caps its addressable population regardless of efficacy. Temporal interference is a frontier technique that may not deliver on its early promise. And the category carries a history of hype, the open-label-to-RCT collapse being its signature failure mode. This is a real segment with a real and unsolved central problem, not a sector on the verge.
The frame
Behavioral health is usually mapped as drugs plus software. The bioelectronic axis is a third territory, hardware that modulates the brain directly, and it is underwatched precisely because it is covered one device at a time rather than as a whole. Seen as a category it has a clear shape: established but reimbursement-starved vagus nerve stimulation, high-promise but sham-troubled deep brain stimulation, and frontier non-invasive temporal interference, all aimed at the patients drugs fail, all stuck on the problem of proving themselves against a sham, and all betting their future on closed-loop systems that respond to the brain rather than override it. Whether it becomes standing coverage is an editorial decision. That it is a genuine and coherent category, rather than a scatter of unrelated gadgets, is not in much doubt, and almost no one is covering it that way.