Latest news with #KevinTracey
New Statesman
22-05-2025
- Health
- New Statesman
The vagus nerve industry
Photo by Getty Images I often saw the vagus nerve when operating, at the base of the brain or in the neck – a small, insignificant thing, the width of a thin matchstick. I knew it to be an important but rather boring nerve that had something to do with digestion and how fast the heart beat. I had no idea that in recent years it would become the centre of a major industry, claiming that vagus nerve stimulation (VNS) will increase our 'vagal tone', leading to a longer, happier and healthier life. In The Great Nerve, Dr Kevin Tracey, a leading researcher into the vagus nerve and its electrical stimulation, tells us the treatment is'poised to revolutionise the way many millions… of people, are cared for… treating the inflammatory threats looming over humanity'. He looks forward to a 'new age of bio-electronic medicine'. Many diseases might benefit from this, he tells us, and he provides a long list of such diseases, ranging from Alzheimer's, Parkinson's and stroke to MS, heart and intestinal disease, depression and headaches. What all these diseases have in common is that they involve, to some extent, inflammation – the activity of the immune system. Stimulating the vagus nerve reduces the activity of the immune system – at least, certain parts of it – and so, the argument goes, VNS will be beneficial. Death might even lose its sting, according to some of its more enthusiastic advocates. You learn at medical school that the body consists of systems, such as the circulatory, pulmonary and renal systems. The nervous system – not just in humans but in most living creatures, including insects – is neatly classified into a hierarchy of central, peripheral and autonomic systems. The central system at the top of the hierarchy consists of the brain and spinal cord, and the peripheral system of the nerves that control movement and relay sensation. The autonomic system is involved in the regulation of the body's health – such as blood pressure, heart rate, the function of the gut. It is in turn subdivided into the sympathetic (SNS) and parasympathetic systems (PSNS), traditionally seen as being in opposition to each other. The former is involved in preparing the body for 'fight or flight' and the latter for relaxation and digestion. Seventy-five per cent of the PSNS is contained in the vagus nerve – in reality a pair of nerves comprised of perhaps 200,000 fibres. It is connected to almost all of the body's major organs (and a few other structures); 80 per cent of the fibres take information about the organs' states to the brain, and 20 per cent relay messages from the brain to the organs. Bodies and brains are complex and the more that we study them the more we discover that everything is interconnected. We may feel that our brains' conscious selves are at the centre of everything, but in reality they are better understood as nodes in a complex network. Our conscious selves have a role – some would say a minor role – to play in our brains' function, which is to keep us alive and well, but most of our brains' vital activities are entirely unconscious. When I was a medical student, it was thought that the nervous system was separate from the immune system – the complex system of white blood cells, genes and proteins that fights infection. The idea that states of mind could influence physical illness was considered to have no scientific basis, even though doctors would sometimes see patient cases that suggested the opposite. Immunology, once seen as little different from quackery, has now moved to the forefront of medical research. Immunotherapy for cancer, for instance, has become immensely important. The immune system is also responsible for a wide range of 'auto-immune' diseases, such as Crohn's and rheumatoid arthritis, when its regulation malfunctions and it starts to attack the body instead of defending it from outside invasion. Thanks to Tracey and other researchers, we now understand that the immune and nervous systems are closely connected in a very complicated relationship. Tracey's lab at the Feinstein Institutes in New York published a paper in Nature in 2002 that was the first to show a direct functional connection between the brain and immune system mediated by the PSNS via the vagus nerve. (It had been known since the 1980s that the SNS was anatomically connected to the immune system, but its functional significance was obscure). The paper showed that stimulating the vagus nerve reduced the release of the cytokine Tumour Necrosis Factor (TNF), cytokines being proteins produced by the immune system to combat infection. TNF is overactive in auto-immune diseases. The 'biologic' drugs that have greatly improved the outlook for many of the patients with these diseases are designed to inhibit cytokines such as TNF. Tracey suggests that electrical stimulation can be a less toxic and more effective way of reducing TNF activity than the very expensive biologics marketed by pharmaceutical companies. He has patented VNS for inflammation and founded a company – SetPoint Medical – that sells vagus nerve stimulators for inflammation. He declares 'full disclosure' that he has stepped down as CEO, though does not tell us whether he still has a financial interest in the company. This is a book for the general reader and is divided into three parts. The first deals with the history of the vagus nerve, the second with the recent research into the relationship between the vagus nerve and inflammation and health (mainly in rodents), and the third is a discussion of the many methods that may, or may not, influence vagal parasympathetic activity and health in humans. Subscribe to The New Statesman today from only £8.99 per month Subscribe He discusses the various methods of stimulating the vagus nerve. It can be done electrically by implanting a device in the neck, or superficially in the outer ear, which is the only place where the nerve innervates the skin. (Ear stimulation leads Dr Tracey into a rather unconvincing discussion about acupuncture.) It can also be stimulated by focused ultrasound, cold exposure, meditation, breathing routines and exercise. He concludes that there is, as yet, little solid scientific evidence, with the exceptions of epilepsy and possibly depression, that these methods have a major benefit on health, longevity or auto-immune diseases. Nevertheless, Tracey exercises, takes cold showers and meditates on the basis of Pascal's Wager – which admittedly I do as well (though I do not meditate), and for the same reason. Like him, I feel the better for it. In an appendix he lists trials – many of them with results pending – into vagus nerve stimulation. (A particular problem with designing VNS trials of health and wellness is that it is difficult to avoid placebo effects, as the subjects know when they are being stimulated). The book makes for fascinating reading, although at times its self-congratulatory and hyperbolic tone can irritate. It follows a precarious course between serious science in rodents and optimistic sales promotion in humans. Central to the book are three case histories of people whose lives are transformed by vagus nerve stimulation. There is a young woman whose Crohn's disease is cured by VNS and who, we learn at the end of the book, now works for SetPoint Medical promoting the practice. There is a Bosnian truck driver who is cured of arthritis. I was puzzled as to why this single case should be in Bosnia and wondered if there was a connection with Tracey's naïveté about the rebuilding of the bridge at Mostar, which he visits. Contrary to what he tells us, there has been no reconciliation since the war between the two mutually hostile communities divided by the bridge. And there is a retired paediatrician in Stockholm who after years of suffering cures himself with vagus nerve stimulation. Fascinating and moving stories but, as Tracey himself states, hoist with his own petard, 'a clinical trial of one or two subjects is more like a fairy tale with a happy ending than a scientific proof'. We may well be on the threshold of a revolution, as Tracey confidently predicts, but the history of medicine is full of promised panaceas that eventually were shown to have only modest benefits in selected cases, or none at all. Only time, and well-conducted clinical trials in humans, will tell, but it would be nice if he were right. Henry Marsh is a former neurosurgeon and author of 'Do No Harm' (Weidenfeld & Nicolson) The Great Nerve: The New Science of the Vagus Nerve and How to Harness Its Healing Reflexes Kevin J Tracey Penguin Life, 320pp, £22 Purchasing a book may earn the NS a commission from who support independent bookshops [See also: The prophet of the new right] Related
Times
13-05-2025
- Health
- Times
Want better health, less anxiety, more sleep? You've got a nerve
Who's acquainted with their vagus nerve? If you're on Instagram or TikTok, you'll know that you need to 'reset' the thing to soothe your nervous system and reduce anxiety, and that investing in 'vagus massage oil' or a vibrating bracelet or pressing an ice pack to your chest will do it. All your ills will be cured. Allegedly. 'The vagus nerve [the longest cranial nerve in the body] is one of the most popular nerves in social media today,' the neurosurgeon Kevin Tracey declares. And it deserves to be celebrated. 'Resting and digesting and keeping calm all depend on your vagus nerve, which is the linchpin of the parasympathetic nervous system,' he says. Tracey is the professor and president of Northwell Health's Feinstein Institutes for
