Mindfulness with paced breathing and lowering blood pressure
September 9, 2020
Science Daily/Florida Atlantic University
Now more than ever, Americans and people all over the world are under increased stress, which may adversely affect their health and well-being. Researchers explore the possibility that mindfulness with paced breathing reduces blood pressure. One of the most plausible mechanisms is that paced breathing stimulates the vagus nerve and parasympathetic nervous system, which reduce stress chemicals in the brain and increase vascular relaxation that may lead to lowering of blood pressure.
According to the American Stroke Association (ASA) and the American Heart Association (AHA), more than 100 million Americans have high blood pressure. Elevated blood pressure is a major avoidable cause of premature morbidity and mortality in the United States and worldwide due primarily to increased risks of stroke and heart attacks. Elevated blood pressure is the most important major and modifiable risk factor to reduce stroke. In fact, small but sustained reductions in blood pressure reduce risks of stroke and heart attacks. Therapeutic lifestyle changes of weight loss and salt reduction as well as adjunctive drug therapies are beneficial to treat and prevent high blood pressure.
Mindfulness is increasingly practiced as a technique to reduce stress through mind and body interactions. In some instances, mindfulness includes paced breathing defined as deep and diaphragmatic with slow rates typically about five to seven per minute compared with the usual rate of 12 to 14. Researchers from Florida Atlantic University's Schmidt College of Medicine and collaborators have published a paper in the journal Medical Hypotheses, exploring the possibility that mindfulness with paced breathing reduces blood pressure.
"One of the most plausible mechanisms is that paced breathing stimulates the vagus nerve and parasympathetic nervous system, which reduce stress chemicals in the brain and increase vascular relaxation that may lead to lowering of blood pressure," said Suzanne LeBlang, M.D., a neuroradiologist, second and corresponding author, and an affiliate associate professor in FAU's Schmidt College of Medicine.
The researchers believe the hypothesis they have formulated that mindfulness with paced breathing reduces blood pressure should be tested. To do so, FAU's Schmidt College of Medicine co-authors are already collaborating with their co-authors from the Marcus Neuroscience Institute, Boca Raton Regional Hospital/ Baptist Health South; and the University of Wisconsin School of Medicine and Public Health on an investigator-initiated research grant proposal to the National Institutes of Health. The initial pilot trial would include obtaining informed consent from willing and eligible subjects and assigning them at random to mindfulness either with or without paced breathing and examining whether there are sustained effects on lowering blood pressure.
"This pilot randomized trial might lead to further randomized trials of intermediate markers such as inhibition of progression of carotid intimal thickening or coronary artery atherosclerosis, and subsequently, a large scale trial to reduce stroke and heart attacks," said Charles H. Hennekens, M.D., Dr.PH, senior author, first Sir Richard Doll Professor and senior academic advisor in FAU's Schmidt College of Medicine. "Achieving sustained reductions in blood pressure of 4 to 5 millimeters of mercury decreases risk of stroke by 42 percent and heart attacks by about 17 percent; so positive findings would have important clinical and policy implications."
According to the ASA and AHA, cardiovascular disease (CVD), principally heart attacks and strokes, accounts for more than 800,000 deaths or 40 percent of total mortality in the U.S. each year and more than 17 million deaths worldwide. In the U.S., CVD is projected to remain the single leading cause of mortality and is rapidly becoming so worldwide. Stroke alone ranks fifth in all-cause mortality in the U.S., killing nearly 133,000 people annually as well as more than 11 percent of the population worldwide.
"Now more than ever, Americans and people all over the world are under increased stress, which may adversely affect their health and well-being," said Barbara Schmidt, co-author, teacher, researcher, philanthropist, bestselling author of "The Practice," as well as an adjunct instructor at FAU's Schmidt College of Medicine. "We know that mindfulness decreases stress and I am cautiously optimistic that mindfulness with paced breathing will produce sustained lowering of blood pressure."
https://www.sciencedaily.com/releases/2020/09/200909100214.htm
'Hunger hormone' enhances memory
July 9, 2019
Science Daily/Society for the Study of Ingestive Behavior
A team of neuroscience researchers at the University of Southern California have identified a surprising new role for the "hunger hormone" ghrelin. Ghrelin has previously been recognized for its unique role in sending hunger signals from the gut to the brain, but, as presented this week at the annual meeting of the Society for the Study of Ingestive Behavior, these new findings suggest that it may also be important for memory control.
Ghrelin is produced in the stomach and secreted in anticipation of eating, and is known for its role to increase hunger. "For example, ghrelin levels would be high if you were at a restaurant, looking forward to a delicious dinner that was going to be served shortly," said Dr. Elizabeth Davis, lead author on the study. Once it is secreted, ghrelin binds to specialized receptors on the vagus nerve -- a nerve that communicates a variety of signals from the gut to the brain. "We recently discovered that in addition to influencing the amount of food consumed during a meal, the vagus nerve also influences memory function," said Dr. Scott Kanoski, senior author of the study. The team hypothesized that ghrelin is a key molecule that helps the vagus nerve promote memory.
Using an approach called RNA interference to reduce the amount of ghrelin receptor, the researchers blocked ghrelin signaling in the vagus nerve of laboratory rats. When given a series of memory tasks, animals with reduced vagal ghrelin signaling were impaired in a test of episodic memory, a type of memory that involves remembering what, when, and where something occurred, such as recalling your first day of school. For the rats, this required remembering a specific object in a specific location.
The team also investigated whether vagal ghrelin signaling influences feeding behavior. They found that when the vagus nerve could not receive the ghrelin signal, the animals ate more frequently, yet consumed smaller amounts at each meal. Dr. Davis thinks these results may be related to the episodic memory problems. "Deciding to eat or not to eat is influenced by the memory of the previous meal," says Davis. "Ghrelin signaling to the vagus nerve may be a shared molecular link between remembering a past meal and the hunger signals that are generated in anticipation of the next meal."
These novel findings add to our understanding of how episodic memories are generated, as well as the relationship between memory and eating behavior. In the future, researchers may be able to develop strategies for improving memory capacity in humans by manipulating ghrelin signaling from the gut to the brain.
https://www.sciencedaily.com/releases/2019/07/190709171807.htm
Stimulating the vagus nerve in the neck might help ease pain associated with PTSD
February 13, 2019
Science Daily/University of California - San Diego
In a randomized, controlled pilot trial, researchers found that participants pre-treated with noninvasive vagus nerve stimulation experienced less pain after heat stimulus than mock-treated participants.
Post-traumatic stress disorder, or PTSD, is a mental condition caused by a traumatic event. People with PTSD may experience intrusive memories, negative thoughts, anxiety and chronic pain. The condition is typically treated with a combination of psychotherapy, anti-depressants and anti-anxiety medications.
It's this connection between mental health and pain that interests Imanuel Lerman, MD, associate professor at University of California San Diego School of Medicine, Jacobs School of Engineering and Qualcomm Institute, and a pain management specialist at UC San Diego Health and Veterans Affairs San Diego Healthcare System.
Lerman especially wants to know how the emotional pain experience may be influenced by the vagus nerve, which runs down both sides of our necks from the brainstem to the abdomen. The vagus nerve also plays a critical role in maintaining heart rate, breathing rate, digestive tract movement and many other basic body functions.
In a study published February 13, 2019 in PLOS ONE, Lerman and colleagues tested noninvasive vagus nerve stimulation as a method for dampening the sensation of pain.
"It's thought that people with certain differences in how their bodies -- their autonomic and sympathetic nervous systems -- process pain may be more susceptible to PTSD," Lerman said. "And so we wanted to know if we might be able to re-write this 'mis-firing' as a means to manage pain, especially for people with PTSD." Lerman led the study with Alan N. Simmons, PhD, director of the fMRI Research Laboratory at Veterans Affairs San Diego Healthcare System and associate professor of psychiatry at UC San Diego School of Medicine.
The team used functional magnetic resonance imaging (fMRI) to get a look at the brains of 30 healthy study participants after a painful heat stimulus was applied to their legs. To determine how the body's sympathetic nervous system responds to pain, they also measured the sweat on the skin of participants before the heat was applied, and at several points as the heat increased.
Half the participants were treated with noninvasive vagus nerve stimulation for two minutes -- via electrodes placed on the neck -- approximately 10 minutes before the heat stimulus. The other half received a mock stimulation.
Lerman and colleagues report three main findings from this study. First, vagus nerve stimulation blunted peak response to heat stimulus in several areas of the brain known to be important for sensory and discriminative pain processing, as well as in emotional pain centers. The treatment also delayed the pain response in these brain regions -- pain-related brain regions were activated ten seconds later in participants pre-treated with vagus nerve stimulation than in sham-treated participants.
Second, the sweat measurements revealed that vagus nerve stimulation altered autonomic responses to painful heat stimulus. For participants pre-treated with vagus nerve stimulation, the sweat response decreased over time, in contrast to the sham-treatment group.
Third, vagus nerve stimulation dampened the usual brainstem centers critical for the fight-or-flight-type responses, which are also known to control the sweat response to pain.
"Not everyone is the same -- some people may need more vagus nerve stimulation than others to achieve the same outcomes and the necessary frequencies might change over time -- so we'll need to personalize this approach," Lerman said. "But we are hopeful and looking forward to the next steps in moving this approach toward the clinic."
Next, Lerman and colleagues will launch a Veterans Affairs Healthcare System-funded clinical trial in San Diego with military veterans, with and without PTSD. They want to determine if at-home vagus nerve stimulation can reduce emotional pain and underlying neural inflammation associated with PTSD. To learn how to participate, please call 858-552-8585.
Vagus nerve stimulation is a form of neuromodulation, an approach to pain management that also includes spinal cord and dorsal root ganglion (DRG) stimulation. The U.S. Food and Drug Administration (FDA) has approved noninvasive vagus nerve stimulator for the treatment of episodic and chronic cluster headache and acute migraine, as well as an implantable device for epilepsy. An implanted vagus nerve stimulator is now being tested in a clinical trial for the treatment of rheumatoid arthritis. Side effects of implanted vagus nerve stimulation can include hoarseness, shortness of breath and nausea.
https://www.sciencedaily.com/releases/2019/02/190213142700.htm
Vagus nerve stimulation boosts post-stroke motor skill recovery
March 27, 2018
Science Daily/University of Texas at Dallas
Researchers have demonstrated a method to accelerate motor skill recovery after a stroke by helping the brain reorganize itself more quickly. In a preclinical study, the scientists paired vagus nerve stimulation with a physical therapy task aimed at improving the function of an upper limb in rodents. The results showed a doubled long-term recovery rate relative to current therapy methods.
In a preclinical study, the scientists paired vagus nerve stimulation (VNS) with a physical therapy task aimed at improving the function of an upper limb in rodents. The results showed a doubled long-term recovery rate relative to current therapy methods, not only in the targeted task but also in similar muscle movements that were not specifically rehabbed. Their work was recently published in the journal Stroke.
A clinical trial to test the technique in humans is underway in Dallas and 15 other sites across the country.
Dr. Michael Kilgard, associate director of the Texas Biomedical Device Center (TxBDC) and Margaret Forde Jonsson Professor of Neuroscience in the School of Behavioral and Brain Sciences, led the research team with Dr. Seth Hays, the TxBDC director of preclinical research and assistant professor of bioengineering in the Erik Jonsson School of Engineering and Computer Science, and postdoctoral researcher Eric Meyers PhD'17.
"Our experiment was designed to ask this new question: After a stroke, do you have to rehabilitate every single action?" Kilgard said. "If VNS helps you, is it only helping with the exact motion or function you paired with stimulation? What we found was that it also improves similar motor skills as well, and that those results were sustained months beyond the completion of VNS-paired therapy."
Kilgard said the results provide an important step toward creating guidelines for standardized usage of VNS for post-stroke therapy.
"This study tells us that if we use this approach on complicated motor skills, those improvements can filter down to improve simpler movements," he said.
Building Stronger Cell Connections
When a stroke occurs, nerve cells in the brain can die due to lack of blood flow. An arm's or a leg's motor skills fail because, though the nerve cells in the limb are fine, there's no longer a connection between them and the brain. Established rehab methods bypass the brain's damaged area and enlist other brain cells to handle the lost functions. However, there aren't many neurons to spare, so the patient has a long-lasting movement deficit.
The vagus nerve controls the parasympathetic nervous system, which oversees elements of many unconscious body functions, including digestion and circulation. Electrical stimulation of the nerve is achieved via an implanted device in the neck. Already used in humans to treat depression and epilepsy, VNS is a well-documented technique for fine-tuning brain function.
The UT Dallas study's application of VNS strengthens the communication path to the neurons that are taking over for those damaged by stroke. The experiments showed a threefold-to-fivefold increase in engaged neurons when adding VNS to rehab.
"We have long hypothesized that VNS is making new connections in the brain, but nothing was known for sure," Hays said. "This is the first evidence that we are driving changes in the brain in animals after brain injury. It's a big step forward in understanding how the therapy works -- this reorganization that we predicted would underlie the benefits of VNS."
In anticipation of the technique's eventual use in humans, the team is working on an at-home rehab system targeting the upper limbs.
"We've designed a tablet app outlining hand and arm tasks for patients to interact with, delivering VNS as needed," Meyers said. "We can very precisely assess their performance and monitor recovery remotely. This is all doable at home."
Expanding the Possibilities for Therapy
The researchers are motivated in part by an understanding of the practical limitations of current therapeutic options for patients.
"If you have a stroke, you may have a limited time with a therapist," Hays said. "So when we create guidelines for a therapist, we now know to advise doing one complex activity as many times as possible, as opposed to a variety of activities. That was an important finding -- it was exciting that not only do we improve the task that we trained on, but also relatively similar tasks. You are getting generalization to related things, and you're getting sustained improvement months down the line."
For stroke patients, the opportunity to benefit from this technology may not be far off.
"A clinical trial that started here at UTD is now running nationwide, including at UT Southwestern," Kilgard said. "They are recruiting patients. People in Dallas can enroll now -- which is only fitting, because this work developed here, down to publishing this in a journal of the American Heart Association, which is based here in Dallas. This is a homegrown effort.
"The ongoing clinical trial is the last step in getting approved as an established therapy," Kilgard said. "We're hopefully within a year of having this be standard practice for chronic stroke."
https://www.sciencedaily.com/releases/2018/03/180327162606.htm