New wearable tech could help track PTSD, sepsis early through nerve activity

A research team led by UC San Diego has demonstrated for the first time that a wearable, non-invasive device can measure activity in human cervical nerves in clinical settings.

To provide medical professionals with a real-time, clinically proven tool for detecting levels of activity in the involuntary nervous system—an early indicator of bodily stress—the researchers designed a flexible, adhesive-integrated electrode array in 2022. The current study applied this approach to detect deep neural activity in a simulated clinical hyperinflammatory model.

“We are encouraged by our results. The device is poised to provide an early diagnostic marker of pathogen infection, or inflammation from a pathological process,” said Imanuel Lerman, the study’s senior author.

The vagus nerve and its role

The device captures what the researchers term Autonomic Neurography (ANG), which encompasses neural activity from the vagus and carotid sinus nerves, as well as other autonomic nerves situated in the neck’s skin and muscles.

Acting as a critical conduit within the autonomic nervous system, the vagus nerve extends from the base of the skull through the torso and abdomen, impacting functions such as digestion, heart rate, and immune responses. Its role in managing the body’s inflammatory reactions to injuries or infections is particularly significant.

This makes it a key area of study for serious conditions like sepsis—a major cause of emergency room fatalities, with around 1.7 million cases annually in the U.S. as reported by the National Institute of General Medical Sciences—and post-traumatic stress disorder, which affects approximately 3.5% of the population according to the National Institute of Mental Health.

Research methodology

To monitor or stimulate the vagus nerve without the need for surgical implants, a novel device employs an advanced technique known as “magnetoneurography.” This method enables precise, non-invasive real-time detection of nerve activity by identifying the magnetic fields generated by the vagus and carotid sinus nerves, which signal the autonomic nervous system in response to potential threats.

In a study involving nine adult participants, researchers first measured baseline inflammation levels by analyzing cytokine concentrations in blood plasma. Subsequently, the subjects were exposed to lipopolysaccharides, bacterial toxins that temporarily induce a state of heightened inflammation similar to that seen in blood infections.

During the experiment, conducted in a magnetically shielded facility, sensors from the device were positioned around the right ear and over the right carotid artery, areas where the vagus nerve and carotid sinus nerve are located. The device tracked heart rate and the magnetic fields associated with nerve activity.

Results

Within thirty minutes of administering lipopolysaccharides to the patients, the device detected alterations in nerve activity below the right ear. This change in nerve activity was validated by blood tests, which also confirmed the release of inflammatory proteins.

The researchers tracked variations in heart rate and observed a significant correlation between nerve firing at both monitoring sites and fluctuations in two key inflammatory cytokines: tumor necrosis factor-alpha (TNF-α) and interleukin-10 (IL-10).

TNF-α is a marker indicating a heightened risk of septic shock, a severe condition where the body’s inflammatory response becomes excessively strong, leading to severe, potentially fatal systemic effects.

Conversely, high levels of IL-10 are associated with immunoparalysis, a state seen during sepsis where the immune system becomes unable to combat infections, leading to uncontrolled microbial or viral growth and potentially fatal outcomes.

Offering insights into PTSD

“With sepsis, every minute counts, and early treatments save lives,” said Troy Bu, the study’s first author, in the press release . “Every hour sepsis is not treated, the likelihood of death increases by up to seven percent. Our technology can provide doctors with an early warning sign of hyperimmune or immunoparalysis response in sepsis.

This technology could enable doctors to pinpoint patients who are at increased risk of excessive immune responses or immunoparalysis—both of which are linked to severe complications and mortality from sepsis.

Additionally, the device may help assess the effectiveness of treatments in reducing inflammation, offer insights into how the nervous system interacts with inflammation in conditions like PTSD and other mental health disorders, and allow for more precise adjustment of therapies based on individual nervous system responses.

The study was published in Nature Communications Biology .