Posted on 24 March 2023
The vagus nerve is one of the most important nerves in the body, connecting the brain to various organs and regulating many bodily functions. This nerve (though there are technically two – one on each side of the body) carries signals in both directions, and is involved in both motor functions (such as controlling the heart rate), carrying sensory information from various organs to the brain, as well as regulating mood, the activity of the immune system and more.
Vagus nerve stimulation is an FDA-approved treatment for epilepsy and depression. Previously, this required a device to be implanted under the skin, but newer non-invasive devices have been developed. This has led to a growing interest in the use of vagus nerve stimulation for a variety of health conditions and perhaps even general health and wellbeing. In this article, we will explore what VNS might have to offer, and how strong the supporting evidence is.
Vagus nerve stimulation is a therapy that involves the use of electrical impulses to stimulate the vagus nerve. Non-invasive methods of VNS involve the use of external devices that apply electrical pulses through the skin, usually at the neck or ear.
It’s important to mention at this point that the phrase ‘stimulating the vagus nerve’ is rather vague. As we already mentioned, the vagus nerve carries out many different functions, not all of which may benefit from being activated. For example, increased vagus nerve activity slows heart rate and lowers blood pressure – not something you would want to combine with certain heart conditions. If you are thinking about using a commercial vagus nerve stimulator, you should consult with a doctor to make sure you are not at increased risk of any complications from increased vagal activity.
VNS has been studied for its potential benefits for a variety of health conditions. Some of this research is extensive, while other research is less so. Some of the potential applications of VNS for general health and wellbeing include:
Over the past decade, many studies have shown that vagus nerve activity suppresses inflammation, mainly by suppressing the production of inflammatory signalling molecules. Inflammation is a common underlying factor in many chronic diseases, including arthritis, diabetes, and cardiovascular disease. However, even though it’s been known for a while that vagus nerve stimulation can suppress inflammation, it’s only quite recently that studies have examined its effects in inflammatory diseases like rheumatoid arthritis. Though small, these studies show promise. One placebo-controlled study of VNS for rheumatoid arthritis showed improvement in 4 out of 6 recipients, while a clinical trial for VNS in Crohn’s disease is currently underway after preliminary studies showed promise. There are good reasons to expect that use of VNS could also improve general health and reduce the risk of chronic disease, but we don’t have enough human evidence for that just yet.
VNS has been shown to have mood-enhancing effects, and is approved for cases of treatment-resistant depression. However, VNS may have benefits for mood in people who aren’t depressed. One study with 82 participants found that non-invasive VNS significantly improved mood compared to a fake treatment. Another, similarly sized study found that participants receiving VNS had better emotional control than those receiving a fake treatment.
VNS has been shown to enhance cognitive function in people with depression. Whether it can also benefit healthy people is less clear as this hasn’t been studied until recently, but there is some supporting evidence. For example, this small study found that people receiving VNS performed better in attention and reasoning tasks than those receiving a fake treatment.
The link between the nervous system, the immune system, and the gut is proving to be a promising target for many interventions, and VNS may be one such intervention. While evidence for benefits of VNS in humans is lacking, we do know that low vagal activity can harm the populations of bacteria living in the gut. Stress can inhibit vagus nerve activity, which is thought to be one of the reasons why stress can promote irritable and inflammatory bowel diseases. There’s also evidence from animal studies that vagus nerve stimulation benefits the gut in other ways, such as by making the intestinal wall less ‘leaky’. Overall, the benefits of VNS for gut health deserve further exploration in humans.
VNS can lower blood pressure, though whether this can be used to benefit general health and wellbeing is uncharted territory. Though blood pressure tends to increase with age, and elevated blood pressure is generally a bad thing, this is not universally the case. Continuous VNS does seem to treat high blood pressure in rats without putting them at risk of bradycardia (low heart rate), and this is being explored as an additional treatment for hypertension in humans. However, whether applying VNS for a limited amount of time each day would have any long-term benefits for your blood pressure is unknown.
Animal studies suggest that VNS can improve responsiveness to the blood sugar control hormone insulin, resulting in greater glucose (sugar) uptake by tissues throughout the body and lower blood sugar. However, there’s insufficient evidence to say whether VNS is beneficial for blood sugar control in humans.
While VNS is still a relatively new therapy, it shows great promise as a non-invasive and effective treatment for a variety of health conditions, and may potentially reduce disease risk and improve general wellbeing in healthy people. If you decide to use a VNS device, make sure you are aware that there could be risks involved for people with certain health conditions, and that research for most applications of VNS are still in relatively early stages. For most people however, non-invasive devices are very safe, have no long-lasting side effects, and may have significant benefits for overall health.
Title image by Lina Trochez, Unsplash
LB0009 FIRST-IN-HUMAN STUDY OF NOVEL IMPLANTED VAGUS NERVE STIMULATION DEVICE TO TREAT RHEUMATOID ARTHRITIS FREE: http://dx.doi.org/10.1136/annrheumdis-2019-eular.8716
Non-invasive Vagus Nerve Stimulation in the Treatment of Crohn's Disease - A Pilot Study (VNS): NCT05165108
Non-invasive vagus nerve stimulation boosts mood recovery after effort exertion: https://doi.org/10.1017/s0033291720005073
Non-invasive vagal nerve stimulation enhances cognitive emotion regulation: https://doi.org/10.1016/j.brat.2021.103933
Effects of Noninvasive Cervical Vagal Nerve Stimulation on Cognitive Performance But Not Brain Activation in Healthy Adults: https://doi.org/10.1111/ner.13313
The Vagus Nerve at the Interface of the Microbiota-Gut-Brain Axis: https://doi.org/10.3389%2Ffnins.2018.00049
Could vagus nerve stimulation have a role in the treatment of diabetes? https://doi.org/10.2217/bem-2017-0008
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