Summary table of somatic neuromodulation therapies for depression

Article written and reviewed by Dr Luca Moretti

Somatic therapies for depression differ in invasiveness, speed of action, level of evidence, need for anesthesia, risks and the type of patient for whom they are most appropriate. Treating them as simple interchangeable alternatives is misleading: ECT, rTMS, tDCS, VNS and DBS occupy very different positions in clinical practice and research.

The table summarizes the essential differences. The regulatory status shown necessarily requires context: device authorizations and indications may vary among the United States, the European Union and individual healthcare systems. In particular, the 2025 FDA approval concerns the specific Flow FL-100 tDCS device, not tDCS as an entire category.

Clinical comparison

Therapy	Invasiveness and procedure	Role in depression	Speed of action	Main limitations and risks
ECT	General anesthesia and a muscle relaxant; controlled induction of a generalized seizure.	Established treatment, particularly important in severe, psychotic, catatonic, high risk or treatment resistant depression.	Among the strategies with the fastest action and greatest acute efficacy; improvement emerges over the treatment course.	Cognitive and memory effects, postictal confusion, anesthetic and cardiovascular risks; requires a dedicated treatment setting.
rTMS/iTBS	Noninvasive; a magnetic coil is placed on the scalp, without anesthesia.	Established treatment for major depression, especially after an insufficient response to medication; several validated protocols are available.	Generally requires multiple sessions distributed over several weeks; accelerated protocols are a specialist area.	Scalp discomfort, headache and a rare risk of seizure; lower expected efficacy than ECT in psychotic or extremely severe presentations.
tDCS	Noninvasive; weak direct current is delivered through electrodes on the scalp. Supervised home based protocols are possible.	The evidence for antidepressant efficacy is growing. Since 2025, the Flow FL-100 device has had a specific FDA approval in the United States for a defined population.	Its effect is assessed over repeated treatment sessions; it is not an emergency therapy.	Heterogeneity of protocols, skin adverse effects and greater uncertainty in highly treatment resistant depression; unsupervised do it yourself use should be avoided.
VNS	Extracranial surgical procedure; a chest implanted pulse generator and an electrode on the left cervical vagus nerve.	Long term adjunctive strategy for highly treatment resistant chronic or recurrent depression; it has had a US FDA indication since 2005.	Slow: benefit may accumulate over months.	Hoarseness, cough, dysphagia, dyspnea, and surgical and hardware related risks; not suitable when an immediate response is required.
DBS	Intracranial neurosurgery with deep electrodes and an implanted pulse generator.	Investigational for extremely treatment resistant depression; multiple targets and connectomic research.	Variable and often gradual.	Hemorrhage, infection, hardware revision and neuropsychiatric effects; sham controlled trials have not yet established efficacy for routine use.

How to interpret the differences

ECT and rTMS are both established somatic therapies, but they address different clinical needs. ECT has a central role when depression is very severe and rapid response is a priority; rTMS provides a noninvasive treatment without anesthesia and with a generally favorable cognitive profile, particularly suitable for nonpsychotic depression that is treatment resistant or associated with medication intolerance.

tDCS is the least equipment intensive technique. Its favorable tolerability profile and the possibility of supervised home based protocols are attractive, but its average efficacy and the strength of the evidence are not equivalent to those of rTMS or ECT in every population. The US authorization of the FL-100 changed the regulatory status of one specific application without turning every direct current stimulator into a validated therapeutic device.

VNS and DBS require implantation. VNS is extracranial and has a long standing US regulatory indication for highly treatment resistant depression; when benefit emerges, it tends to develop slowly and may be durable. DBS is intracranial and remains experimental for depression despite encouraging results in some cohorts.

Choosing the strategy

There is no mandatory sequence that is identical for every patient. The decision integrates diagnosis, severity, urgency, the number and quality of failed treatments, previous response to somatic therapies, neurological and cardiovascular comorbidities, concomitant medications, preferences and access to specialist centers. A patient with catatonia or rapid physical deterioration does not present the same clinical problem as a stable patient with long standing treatment resistant depression.

The term resistant must also be used rigorously. Before progressing to more invasive procedures, it is necessary to verify that previous treatments were adequate and that symptoms are not being maintained by pseudoresistance, an incomplete diagnosis, unrecognized bipolar disorder, substance use, sleep disorders or medical comorbidities.

Finally, acute response is only one component of the outcome. After ECT or rTMS, relapse prevention must be planned; VNS and DBS are inherently chronic treatments that require device programming and management; tDCS likewise requires a continuation plan consistent with the protocol and the overall treatment strategy.

The sequence is not rigid. Previous response to a technique, preferences, local availability, need for anesthesia, presence of implantable devices and the ability to adhere to an outpatient treatment course can change the choice. “Resistance” is not a single category either: the number and adequacy of failed treatments, episode duration and the presence of comorbidities affect both prognosis and the benefit to risk balance. The table should therefore be read as a tool for comparative guidance, not as an automatic prescribing algorithm; the final indication requires specialist assessment and an explicit definition of the clinical objective.

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