Running from the abdomen up to the brain, it is perhaps not a surprise that the vagus nerve finds itself at the center of all kinds of medical research. Scientists have previously shown that stimulating this particular nerve could lead to new treatments for depression, epileptic seizures and even awaken consciousness after a 15-year stint in a vegetative state. Scientists at the University of Leeds have now added another to this list of exciting possibilities, demonstrating how targeting the vagus nerve could help slow some of the effects of aging.
What led the scientists from the University of Leeds' School of Biomedical Sciences to the vagus nerve is the key role that it plays in the body's parasympathetic system. This makes up one branch of the body's autonomic nervous system, which controls unconscious functions like breathing and digestion. The other branch is known as the sympathetic system, which takes care of more intense tasks and our "fight or flight" responses.
These two branches balance each other out as we move through life, but there comes a time that the sympathetic branch assumes more and more control. This can mean greater vulnerability to diseases, irregular bodily functions and other typical hallmarks of an aging human.
The thinking is that by stimulating the vagus nerve we might be able to address this imbalance and restore a healthy equilibrium between the parasympathetic and sympathetic systems. And it wouldn't necessarily involve invasive surgery to implant a stimulation device. Rather, it could be as simple as a tickling sensation on the ear on a regular basis.
Conveniently, a tiny off-shoot of the vagus nerve can actually be found on the skin of the outer ear. This raises the prospect of spurring the nerve into action through a therapy known as transcutaneous vagus nerve stimulation (tVNS). To explore this idea with respect to aging, the research team enlisted 29 healthy volunteers aged 55 and over, and administered tVNS therapy over a period of two weeks, for 15 minutes every day.
The treatment did indeed swing things back toward a healthy balance of parasympathetic and sympathetic activity, with recipients exhibiting improved autonomic function as a result. Some patients also reported changes to their quality of life through improved mood and quality of sleep. Importantly, the subjects with the greater imbalance before the study exhibited the greatest improvements, which means it may be possible to target this therapy at those likely to benefit the most.
"The ear is like a gateway through which we can tinker with the body's metabolic balance, without the need for medication or invasive procedures," says lead author Dr Beatrice Bretherton. "We believe these results are just the tip of the iceberg. We are excited to investigate further into the effects and potential long-term benefits of daily ear stimulation, as we have seen a great response to the treatment so far."
The team has published its research in the journal Aging.
Source: University of Leeds
