Vagus nerve stimulation (VNS) is one of only a handful of neuromodulation therapies with FDA approval for treatment-resistant depression — and a landmark 2026 trial has provided the strongest evidence yet that it delivers durable, meaningful relief for people who have failed numerous other treatments. Understanding how VNS works for depression, who it helps, and how it compares with other options puts this therapy in proper clinical context.
How VNS Reaches the Brain’s Mood Circuits
An implanted VNS device delivers intermittent electrical pulses to the left cervical vagus nerve via a helical electrode wrapped around it. Approximately 80 percent of vagal fibres are afferent — they carry information upward toward the brain. These afferents terminate primarily in the nucleus tractus solitarius (NTS) in the brainstem, which serves as a relay hub connecting to structures critical for mood regulation.
From the NTS, vagal signals project to the locus coeruleus — the brain’s primary source of noradrenaline — and the dorsal raphe nucleus, a major serotonin-producing centre. These two nuclei send widespread projections throughout the cortex, limbic system, and prefrontal regions. By driving activity in these monoaminergic pathways, VNS effectively modulates the same neurotransmitter systems targeted by antidepressant medications — but through a bottom-up electrical route rather than systemic pharmacology.
Additional downstream effects include modulation of the amygdala (reducing threat-related hyperactivity), changes in prefrontal cortical activity (improving emotional regulation), increased brain-derived neurotrophic factor (BDNF) expression supporting neuroplasticity, and anti-inflammatory effects through the cholinergic anti-inflammatory pathway. This multi-target mechanism may explain why VNS can help patients who have not responded to medications that target only one or two neurotransmitter systems.
FDA Approval and Clinical History
The FDA approved VNS for treatment-resistant epilepsy in 1997 and for treatment-resistant depression in 2005. The depression approval was controversial because the pivotal trial at the time showed improvement in the VNS group compared with baseline but did not achieve statistical significance against a sham-control group at the primary endpoint. However, open-label extension data consistently showed that VNS benefits accumulate over time — response rates increased substantially between the first and second year of treatment, a pattern unusual among antidepressant therapies and suggestive of progressive neuroplastic changes.
The therapy is indicated for adults with chronic or recurrent major depression who have failed at least four adequate antidepressant treatments. In practice, patients receiving VNS have typically failed far more — the average in the RECOVER trial was 13 prior treatments.
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The RECOVER Trial: Landmark Evidence
Published in January 2026 in the International Journal of Neuropsychopharmacology, the RECOVER trial was the largest and most rigorous VNS depression study to date. Nearly 500 patients across 84 US sites had devices implanted, but only half were activated during the first year — a sham-controlled design intended to address the limitations of earlier trials.
The primary outcome on the Montgomery-Asberg Depression Rating Scale (MADRS) did not reach statistical significance between active and sham groups during the blinded first year — a result that echoes the original pivotal trial and reflects the challenge of maintaining adequate blinding and the slow onset of VNS effects. However, patients with active devices spent significantly more time with improved depressive symptoms, quality of life, and daily function compared with the sham group on multiple secondary measures.
The durability analysis of 214 patients who received active stimulation from the start was more striking. At 12 months, approximately 69 percent had a meaningful response — at least 30 percent symptom reduction — on at least one outcome measure. By 24 months, over 80 percent of those responders maintained or increased their benefit. Among patients achieving 50 percent or greater symptom reduction at one year, 92 percent still showed benefit at two years. Thirty-nine patients — over 20 percent of the active treatment group — achieved full remission by 24 months. Notably, nearly one-third of patients who had not responded at 12 months reported benefit by 24 months, confirming the slow-onset pattern observed in earlier studies.
The Procedure and What to Expect
VNS implantation is an outpatient surgical procedure typically lasting 60–90 minutes under general anaesthesia. A pulse generator (about the size of a stopwatch) is placed under the skin below the left collarbone, and a lead with electrodes is threaded to the left cervical vagus nerve. The device is programmed to deliver stimulation in cycles — typically 30 seconds on, 5 minutes off — and parameters are adjusted over weeks to months to optimise the balance between efficacy and tolerability.
Patients should understand that VNS is not a rapid-acting treatment. Most improvement develops gradually over 6–24 months. Common side effects include hoarseness or voice changes during stimulation cycles (reported in 30–60 percent of patients initially, often decreasing over time), cough, throat discomfort, and shortness of breath. These occur during the “on” periods and are generally manageable by adjusting stimulation parameters. VNS is used alongside — not instead of — other depression treatments, including medications and psychotherapy.
Transcutaneous VNS for Depression
Non-invasive transcutaneous auricular VNS (taVNS), which stimulates the ear’s vagal branch through skin electrodes, is being actively investigated for depression. Multiple randomised controlled trials have shown that taVNS can reduce depressive symptoms, with several studies demonstrating effects on the same brainstem and limbic circuits as implanted VNS, confirmed by functional neuroimaging.
A 2024 meta-analysis pooling data from taVNS depression trials reported a significant effect on depression severity compared with sham stimulation, though effect sizes were smaller than those reported for implanted VNS. The advantages of taVNS are accessibility (no surgery, devices costing a fraction of implanted systems), safety (minimal side effects), and the ability to self-administer at home. The limitations are that optimal stimulation parameters, treatment duration, and long-term efficacy have not yet been established. TaVNS for depression remains investigational and is not FDA-approved for this indication.
How VNS Compares with Other Neuromodulation
VNS occupies a specific niche in the neuromodulation landscape for depression. Transcranial magnetic stimulation (TMS) is less invasive and has FDA approval for depression, but its effects tend to be shorter-lived and it typically requires repeated courses. Electroconvulsive therapy (ECT) remains the most acutely effective treatment for severe depression, with response rates of 50–70 percent, but requires repeated anaesthesia and carries cognitive side effects that limit long-term use. Deep brain stimulation (DBS) targets mood circuits directly but remains experimental for depression and involves more complex neurosurgery.
VNS distinguishes itself through durability: its effects build over months and persist for years in responders, with the RECOVER trial showing maintained benefit at 24 months. For patients with chronic, treatment-resistant depression who need sustained long-term improvement rather than acute symptom relief, VNS fills a gap that other modalities do not.
Anyone considering VNS should work with a psychiatrist experienced in neuromodulation therapies to determine whether they meet eligibility criteria and to set realistic expectations about the timeline for response.
Depression treatment is evolving rapidly, and the vagus nerve is at the centre of some of the most promising advances. Get the Vagus Nerve & Me eBook for a complete guide to how vagal pathways influence mood and what the latest science says about stimulation therapies.
