Vagus nerve stimulation: A new way to treat PTSD and other mental health disorders
Brain plasticity is the key to healing - how best to harness that tool
Some mental health disorders respond well to talking therapies. Others only a little, or not at all. In post-traumatic stress disorder, the response to a trigger is hardwired into the brain. You have to dig deeper to tackle the problem. There are new and promising digging techniques that can do this.
Happily for we humans, the brain is not ‘fixed’. Nothing is set in stone. It is plastic, meaning that it is a dynamic structure that responds to thoughts, stimuli and events. It rewires and reorganises itself, creating new connections and dispensing with underused ones.
This neuroplasticity can be activated by talking therapies, certain aspects of diet and something called vagus nerve stimulation.
Vagus nerve stimulation (VNS) is a technique that is already approved for use in the US for various psychiatric disorders, including major depressive disorder. It has been FDA-approved since 1997 as treatment for drug-resistant epilepsy.
The vagus nerve is the longest nerve in the body, extending from the brainstem to the gut and most organs. It is a significant component of the parasympathetic nervous system, which oversees digestion, heart rate and respiration. It also regulates the stress response, connecting mind and body and restoring calm, once any threat has passed.
But the problem is that the threat doesn’t always pass. At least, not for the subconscious mind. In PTSD the past is very much alive and active in the present.
Many traumatic events can trigger PTSD – physical or sexual assault, serious accidents, injury, frightening experiences, natural disasters. In most people, symptoms of PTSD eventually fade. For a significant minority, they don’t.
PTSD is about conditioned fear. It is debilitating and affects daily life, with the traumatic experience often relived through nightmares and flashbacks. There may be problems sleeping and concentrating.
VNS aims to extinguish that fear by facilitating plasticity in networks associated with fear learning. It does this by delivering short bursts of electrical impulses to the vagus nerve.
Many people with PTSD do not respond to existing therapies alone, such as cognitive behavioural therapy. A just-published, pioneering clinical study examined the effects of VNS combined with CBT on nine people diagnosed with treatment-resistant PTSD. VNS was delivered via a device implanted in the neck, over 12 sessions.
The VNS eliminated PTSD in all participants – even at six months post treatment. There were no adverse effects.
This effect was considered to be consistent with the notion that VNS changes plasticity in a way that enhances recovery.
‘VNS therapy resulted in significant, clinically-meaningful improvements in multiple metrics of PTSD symptoms and severity compared to baseline’
This study was undertaken by scientists based at the University of Texas at Dallas and Baylor University Medical Center and the results published online in Brain Stimulation. A second trial is currently underway to confirm the findings.
The impetus for this study arose following the publication in 2017 of an experiment on rodents. A sorry bunch of rats were subjected to unpleasant stresses, like isolation and being forced to swim. They developed conditioned fear, just as humans would. Like humans with PTSD, rats do not extinguish this fear.
They were treated with VNS, and this treatment successfully eliminated their PTSD-like symptoms.
In PTSD, there are alterations in brain structure and function, including a hyperactive amygdala.
The amygdala is a cluster of almond-shaped structures that form part of the limbic system near the base of the brain. It is responsible for processing emotional reactions, particularly those involving fear and anxiety. It is this part of the brain that activates the stress response.
For anyone not keen on an implant, there are dietary techniques that can also stimulate the vagus nerve in a positive way.
The vagus nerve connects the brain to the gut, and bacteria in the gut that form part of the microbiome transmit messages to the brain along this nerve. They also make neurotransmitters.
Some bacterial strains produce the neurotransmitter serotonin, which can act directly on vagus nerve endings.
Serotonin is found at both ends of the vagus nerve. It is an important mood regulator, and dysfunctional serotonin production is considered to be one of the main factors contributing to the development of depressive symptoms.
It’s also a precursor of melatonin, a hormone secreted in the brain’s pineal gland that regulates your internal body clock and helps you fall asleep at night.
The serotonin in your gut does not enter the brain, but it sends it messages via the vagus nerve, and the transmission of those messages is directed by beneficial gut bacteria.
The most researched of all the probiotics, in terms of showing beneficial effects on anxiety and depression, are the Bifidobacterium and Lactobacillus. In particular, treatment with Lactobacillus rhamnosus increases levels of the neurotransmitter GABA and changes activity in the amygdala.
GABA (gamma-aminobutyric acid) is the main inhibitory neurotransmitter, and through its regulation of the vagus nerve has a calming effect, reducing stress and anxiety.
Lactobacillus bacteria are also present in fermented foods including yogurt, kefir (fermented milk drink) and sauerkraut (fermented, shredded cabbage).
When it comes to raising serotonin, the amino acid tryptophan is also essential.
Tryptophan is an ‘indispensable’ amino acid, meaning that the body cannot make it and you must obtain it directly from food. It is able to cross the blood-brain barrier to enable serotonin synthesis by the central nervous system.
The richest sources of tryptophan are the complete, or quality proteins: meat (especially poultry), fish, eggs and milk.
Although PTSD is a mental disorder, it is also strongly associated with a wide range of metabolic abnormalities. That suggests that certain dietary strategies that help normalise metabolism could be a viable treatment option.
One diet that has attracted attention in this regard is the ketogenic diet, already established as an effective treatment of other neurological and mental disorders.
Interestingly, a study that combined VNS and the ketogenic diet in 33 children with drug-resistant epilepsy resulted in much less seizure frequency than one modality used alone.
‘The proportion of patients reporting a greater than 50% seizure reduction over all visits was 62% … The proportion of a patient's visits with at least a greater than 50% reduction in seizure frequency had a median of 71%’
What about PTSD? There may good news here, too. Just last year (October 2024), a first-of-its kind, small feasibility study (just three participants) investigaged whether a ketogenic diet supplemented with additional ketones could have a positive effect. After 21 weeks of treatment, the result was that ‘patients were compliant and there were clinically meaningful improvements in PTSD symptoms.’
The study was way too small to offer any definite conclusions, but it does offer hope. The ketogenic diet is something anyone can try.
Combining therapies seems to be the best approach to PTSD. For some people, it may be worth combining dietary changes with a non-invasive VNS device.
Non-invasive VNS (nVNS) devices also deliver electrical impulses to the vagus nerve at the neck or ear level and are now readily available to purchase. Do they work? It looks that way, according to the research.
Emerging evidence indicates that nVNS may effectively reduce PTSD symptoms by enhancing parasympathetic activity, attenuating sympathetic hyperactivity, and improving overall autonomic function.
Neuroplasticity represents hope for PTSD sufferers, as it does for people with other psychiatric and neurological disorders. If the drugs don’t work, VNS (whether invasive or otherwise), combined with the right diet may be the tool that changes the brain’s wiring system and extinguishes the fear.
Would this treat Dysautonomia?