What is Vagus Nerve Stimulation?

Over the years, clinicians have developed many different types of depression treatments. Antidepressant drugs, brain stimulation, and psychotherapy are all effective and proven options.

However, as our understanding of depression expands, we are finding that depression isn’t only linked to the brain and emotions. Many other parts of the body, including the digestive and nervous systems, play a role.

This has led to other promising therapies, such as vagus nerve stimulation, which can provide an alternative option for people with treatment-resistant depression.

How the Vagus Nerve Works and Its Role in Depression

The vagus nerve is a pair of cranial nerves that run from the brainstem to the abdomen. Since these nerves are so long and cross through so many different organs, they are often called the body’s “superhighway.”

The vagus nerve is involved in all types of functions, from breathing to digestion. It relays information from the digestive system to the brain and plays a central role in gut-brain communication.

The vagus nerve is also the main line of communication for the parasympathetic nervous system, also known as our “rest and digest” mode. In this role, the vagus nerve promotes relaxation, which helps us transition out of fight-or-flight mode. While our understanding of the vagus nerve is still in its early stages, there is some evidence that its strength may correlate with higher resilience to stress.

We can simplify the vagus nerve’s complex function by thinking of it as a messenger system, sending information to and from the gut, skin, and organs to the brain for interpretation. If it is fully operational, the nerve should filter out the more distressing messages and only relay neutral, or calming, information.

However, if the vagus nerve is weak or underactive, it cannot filter out these stressful messages. According to several studies, this could contribute to depressive symptoms. An underfunctioning vagus nerve is also associated with the following conditions:

• Irritable bowel syndrome
• Fainting
• Acid reflux
• Slow/fast heart rate

There is also evidence that the vagus nerve may be linked to post-traumatic stress disorder and anxiety.

Strengthening the Vagus Nerve with Vagus Nerve Stimulation

The vagus nerve can weaken for many reasons. As we age, all of our nerves, including the vagus nerve, become less sensitive and responsive. The vagus nerve can also become inflamed or damaged from injuries, chronic illnesses like diabetes, or high-stress levels.

Stimulation can boost vagal tone. Vagal tone reflects how well the vagus nerve is functioning. One way to measure vagal tone is through heart rate variability. When HRV is high, the time between heartbeats varies more.

While there are many ways to stimulate the vagus nerve, vagus nerve stimulation (VNS) is a specific type of medical procedure prescribed for treatment-resistant depression and other conditions. VNS is not recommended for everyone, but it can provide hope for people who have not found relief from other depression treatments.

VNS works by implanting a current-emitting device into the body, usually on the left side of the chest. The device is then attached to the left vagus nerve and gives off electric pulsations at regular intervals. The wearer cannot feel these pulses but may notice changes to their mood and physical reactions to stress as the vagus nerve strengthens.

VNS is an approved treatment for depression and epilepsy in the European Union and the United States. There are also non-invasive versions of VNS that stimulate the nerve through the neck and ears in development.

It is also possible to stimulate the vagus nerve through non-medical techniques. Clinical psychologist Dr. Arielle Schwartz lists a few proven methods:

• Cold-water baths
• Meditation
• Singing
• High-intensity Interval Training

While none of these methods are approved for treating clinical conditions, they can help people feel more balanced and calm in their everyday lives.

Vagus Nerve Stimulation vs Other Types of Stimulation

VNS is not the only depression treatment that uses electricity. Transcranial direct current stimulation (tDCS) is another approach that uses neuromodulation. This means, like VNS, tDCS works by activating a specific part of the nervous system.

There are some similarities and a few important differences between the two techniques.

How tDCS Works

tDCS is suitable for nearly anyone with major depressive disorder. It can be used as the sole treatment or combined with antidepressants and lifestyle changes.

tDCS devices generate electric pulses to stimulate the targeted nerves on the dorsolateral prefrontal cortex, which is the front of the brain. The device emits pulses through a headset position on the forehead. The electrodes are placed on the skin – no surgery or insertion is necessary. The pulses are painless and there are no serious side effects.

Differences between tDCS and VNS

VNS in its current variation must be surgically implanted and requires general anesthesia. Although VNS itself has a relatively low side effect rate, many of its potential complications, such as infection, stem from the placement surgery.

As a result, VNS is considered a last-resort depression treatment. It is generally not advised as an option unless other treatment types, like antidepressants and electroconvulsive therapy (ECT), have failed.

While current evidence shows VNS is safe and effective, studies are limited. One reason for this is that there aren’t many people who qualify for VNS. Also, the treatment is expensive, and some insurers won’t cover the costs.

tDCS is less expensive with fewer restrictions. Also, tDCS is delivered on the outside of the body, so no surgery is required. Since tDCS is minimally invasive and well-tolerated, it has been tested amongst much larger groups of people. This has generated a lot of evidence showing its effectiveness and safety for treating depression.

Although tDCS is traditionally delivered in the clinical setting, Flow Neuroscience created a portable version of the tDCS device that can be used at home. A Flow headset can be ordered online without a prescription or waiting time. The Flow tDCS device is also a fraction of the cost of traditional tDCS or VNS. Learn more about Flow tDCS here.

Why We Need More Treatment Options for Depression

Treatment-resistant depression is surprisingly common – around a fourth of people with major depressive disorder do not respond to currently available options. For this reason, emerging treatments like tDCS and VNS are so important for improving outcomes.

Though it is still in the early stages, VNS is one of many promising new depression treatments that will give people navigating depression more options. As non-invasive versions come to market, researchers can gather more evidence and gain a better understanding of VNS’ long-term benefits.

These developments may also make VNS cheaper and more accessible, giving millions of people the chance to find relief from their depressive symptoms.

Read more about: What is tDCS?