by Emma Nagel
art by Ariel Brown-Oghaart
Close your eyes, think of your happy place, and count to ten… did you feel your body relax? Did you notice your heart rate and breathing slow? This is one of the many examples of how your mind and body are connected. You’ve probably never thought about how your brain does this, but your eyes likely start to water after thinking of a poor test grade, or your heart pumps faster when you realize you've been reading Grey Matters instead of doing your work. Have you ever thought about the reverse? The mind serves as your body's control system; in return, your body is constantly responding to and affecting your mind. Inflammatory reactions in your gut and body can produce real emotions, which could have serious consequences like depression [1]. The mind and body are intimately connected, and utilizing this relationship could lead to living better, healthier lives.
One clear relationship between the mind and body is how the sympathetic nervous system coordinates its response to stress, known as the “fight-or-flight” response. This is the idea that hormones are released in your brain when stressed or relaxed, which triggers a chain of biological reactions that change your breathing and heart rate accordingly [2]. Higher stress levels increase breathing and heart rate, eventually activating cortisol (a stress hormone). Cortisol sends glucose into your bloodstream, allowing your body to be metabolically active and reserve energy to fight potential stressors [3]. The way the mind regulates and controls the body, consciously or subconsciously, has always been thought to be through hormones and signaling pathways. However, a recent study pursued a more nuanced brain mapping that linked our brain’s mechanism for conscious thoughts and cognitive functioning to physiological responses like breathing and heart rate. These physiological responses were previously thought to operate separately and be unaffected by our thoughts [4].
Thoughts and mental states significantly impact health, for better or worse. An experiment studying the effects of stress on heart function monitored the hearts of eighteen men before, during, and after a mental stress test where they were told they had to defend themselves for two minutes after being accused of shoplifting. The men’s stress response produced elevated heart rates, causing pressure on vessels in the heart to accommodate for the increased blood flow. Even though the effects of stress are temporary, if the stress is persistent, this abnormal blood pressure is linked to narrower, weakened arteries, which could lead to heart attacks, strokes, and several fatal diseases over time [5]. Chronic stress has also been tied to inflammation, which is linked to heart abnormalities and is considered a precursor to diseases if it happens frequently [6]. By attaching a probe to the brains of mice, introducing them to stressors, and monitoring them, scientists discovered the effects of the increase in energy caused by stress. This extra energy, exerted and transferred in our body through a molecule called adenosine triphosphate (ATP), activates a system of receptors called the purinergic P2X receptor 7 (P2X7), which activates immune cells. Activation of immune cells, which fight infections or intruders in the body, leads to an inflammatory response since these cells are produced in abundance and swell in the area to fight the problem [7].
While the mind can potentially harm our health, it can also heal and benefit us. Meditation, a process of focusing your attention and relaxing the body, often by concentrating on breathing, has been known to resolve stress and improve our physical health. When cultivated and used regularly, this practice can produce significantly lower cortisol levels and has even been shown to produce longer telomeres, DNA sequences in chromosomes important for lifespan [8]. Less cortisol means reduced stress levels, reflected in studies monitoring the effects of meditation on blood pressure and inflammation. In addition, an accumulation of studies found that meditation can significantly reduce blood pressure [9]. A study following inflammation markers before and after meditation found that this mindfulness reduces inflammation caused by the nervous system [10].
The neuroscience behind meditation is still poorly understood, and demands further research, as accurately measuring its effects can be challenging. Studies often compare the brain activity of those experienced in meditation to those of non-meditators, making it hard to decipher if the observable differences are pre-existing and may have drawn them to meditation in the first place or whether these changes are primarily caused by meditation or other factors like changes in lifestyle and diet. Long-term studies that monitor novice meditators and track their brain activity as they become more skilled are relatively rare. However, they have shown promising results, such as improved attention and lower stress levels [11]. Also, since there are many meditation methods, different studies use different techniques. It can be hard to correlate the studies to ensure that the participants do it “correctly.” These setbacks to reliable studies lead to different results and areas in the brain associated with meditation [12]. However, the most prevalent theory is that meditation increases the activity in the default mode network (DMN), the part of the brain associated with daydreaming and emotion regulation, and the left dorsolateral prefrontal cortex (left dlPFC), the area responsible for regulating thoughts and actions to achieve goals. The DMN and left dlPFC are thought to work together to actively relax the body, regulating stress levels and inflammation [13].
Another area of the brain central to mind-body interactions is the vagus nerve. Similar to the pathways in the brain activated by meditation, this nerve also works to lower stress and inflammation. The vagus nerve is connected to the brainstem that runs from the neck to the abdomen and large intestine, playing a vital part in the “brain-gut axis,” the communication system between the brain and the digestive system. It regulates behavioral and hormonal responses, and stimulation of this nerve can produce similar brain effects to meditation. This treatment applies electrical impulses to the nerve either directly, by implanting a device on the nerve to intermittently send electrical pulses, or by simply attaching a pulsing device to the ear and indirectly sending signals to the vagus nerve. This has been used to relax people, induce anti-inflammatory properties, and is at the forefront of medicine to treat psychiatric and gut inflammation issues [14]. Interestingly, the nerve was originally targeted to prevent seizures and epilepsy, but when the depressive symptoms in patients being treated for epilepsy were reduced, it started to be used for the treatment of depression [15]. Since the most effective way to stimulate the nerve is through surgery, its treatment for depression has been limited to patients who have not responded to at least four prescribed medications. A study testing the response of vagus nerve stimulation for depression found that symptoms were significantly reduced. Brain imaging studies suggested that the nerve affects the DMN to produce these results [16].
Whether through meditation or vagus nerve stimulation, there is vast potential to assist the mind and have active control over the functioning of our bodily systems. This may seem like a one-way street, but the body has just as much influence over the brain. Most people know the gut conveys information about appetite, telling the brain whether or not we are hungry since the effect of this communication is immediate. Still, many important things the gut relays go “unnoticed.” The gut has a complex nervous system called the enteric nervous system (ENS), commonly referred to as the second brain. The ENS not only ensures the gut is functioning properly but also helps communicate with the brain by sending signals in the bloodstream or nerves, such as the vagus nerve. An overwhelming ninety percent of signals traveling through the vagus nerve go from the gut to the brain rather than the other way around, as you might expect [17].
An example of this communication’s effect on the brain is the link between the gut and depression. The immune response, which causes inflammation in the gut, has been shown to increase symptoms of depression [18]. This was discovered because those with depression have elevated levels of inflammation, and studies have shown signs of active neuroinflammation during depressive episodes [19]. In 2012, a study found that one in four people taking a pro-inflammatory drug used to treat hepatitis C developed depressive symptoms, supporting inflammation's role in depression [20]. There is evidence that this connection was evolutionarily beneficial and inherited through the generations since the symptoms of depression, such as social avoidance and melancholy, promoted being immobile, allowing energy to be preserved to fight whatever was causing the inflammation. However, the process through which inflammation causes depression is unclear. There are cellular and hormonal pathways that are thought to be significant, and data supports the idea that the inflammatory response in the gut leads to inflammation in the brain, which causes depression. Also, inflammation can lead to the reduced neural activity of serotonin, a neurotransmitter that regulates emotion and is associated with depression [1]. Several studies found that anti-inflammation drugs can be used to decrease depressive symptoms. However, not all those depressed have inflammation, and this promising new treatment is really to target a subgroup of those with both depressive and inflammatory symptoms [21].
Why has utilizing this crucial relationship between the mind and the body been taken for granted? In his book, “The Mind-Gut Connection,” Emeran Mayer summarizes the history of medicine with an interesting analogy. Imagine your body is a car: each organ has its mechanism that operates independently and serves to function the whole. Doctors are the mechanics who fix each problem as it arises for any malfunctioning part. For years, physicians have used this model in medicine, treating illnesses as problems within specific organs rather than considering the body as a whole. As cars evolved and technology advanced, so did our view of the human body. Instead of organs and mechanisms in the body being viewed as isolated entities, they are entangled, complicatedly intertwined mechanisms that communicate and influence each other [17]. Our view of the body has become more nuanced, and while the idea of using mind-body connections is still being talked about with fluffy language like “auras” and considered alternative medicine by some, it has made considerable strides in today's world of modern medicine. Many universities, including Columbia and Harvard, have labs devoted to mind-body research, and mind-body medicine is now incorporated into the curricula of medical schools [22]. Programs committed to using mindfulness to reduce stress are being implemented to help those suffering from chronic illnesses, as well as by healthy college students [23].
Not only is harnessing the connection between the mind and body vital for treating diseases, but it can be beneficial to maintaining our health in our daily lives. Practices like meditation are essential to lowering stress and inflammation, and protect us from numerous diseases. On the other side, recognizing the gut’s effect on mindset can help treat mental struggles you may be facing. It is important to note that harnessing this connection between the mind and body is not curative. More research is still being directed towards studying brain pathways involved in diseases, programs that use mindsets and emotion regulation to treat diseases, and how the gut is involved in mental disorders. However, the studies show how beneficial utilizing this connection can be. So, next time you feel stressed, take a moment to do some self-care and meditate. Right now, you can take the time to close your eyes, practice deep breathing, and finish the rest of this Grey Matters edition…
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