The Mind-Body Cure. Bal Pawa
Understanding Stress Hormones and the Brain
Everyone has a different definition of stress, but at a basic level it refers to a state of mental or emotional strain caused by a physical, chemical, or emotional factor. Stress comes in all shapes, sizes, and quantities, and each of us perceives it differently. All of us experience daily stress, and our bodies can adapt to handle not only everyday stress but unpredictable and acute stress exposure too. For example, we encounter stress when avoiding immediate dangers such as an oncoming car—our SNS is activated, we go into a fight-or-flight reaction, and after the few seconds of fear, we realize the collision has been averted. Our PNS then kicks in, and our rest-and-digest response allows our body to relax. Some stress can even be positive: we may feel an excited adrenaline rush when skiing down a mountain, running a race, or meeting a deadline. Those events, however, are not usually sustained. When stress becomes prolonged, chronic, and excessive, it causes disease in our body. But how and why does it get that way?
➤ Our Intel Processor: The Hypothalamus
The brain has a built-in “Intel processor” called the hypothalamus, an almond-sized area at the base of the brain. Like a busy traffic cop, it is continuously scanning the environment for signs of danger, processing the information at lightning speed, and directing a multitude of functions to keep us safe. It gets us up in the morning and starts the adrenaline flowing. It controls the molecules that allow us to experience emotions such as exhilaration, happiness, anger, or upset. The hypothalamus is also a bit like a thermostat, always aiming for homeostasis. It controls how much we eat, regulates our body temperature, and acts as our “emotion detector.”
The hypothalamus sends instructions to the body in two ways. First, it controls blood pressure, heart rate, breathing, digestion, and all the sympathetic and parasympathetic functions through the ANS, which speeds up or slows down body functions. Second, it regulates growth and metabolism as well as emotion by communicating with the pituitary gland, the pea-sized endocrine gland at the bottom of the hypothalamus that we often refer to as the “master gland.” The instant processing mechanism of the hypothalamus works efficiently using all the senses and memory storage, which communicate with each other. Then it directs the pituitary gland to regulate our response to our environment through hormones and other chemicals. Together, they decide when to release each hormone and how much to release.
The hypothalamus and the pituitary gland also form part of the limbic system, an area of the brain that interprets emotional responses, stores memories, and regulates hormones.1 Two key structures of the limbic system are the almond-shaped amygdala and the tiny nub called the hippocampus that lies adjacent to it. The amygdalae (there is one on each side of the brain) determine which memories are stored and where in the brain each of those memories is to be kept, and the hippocampi (there is also one of these on each side of the brain) send the memories to their assigned part of the brain for long-term storage and retrieve them when necessary.
➤ The Hypothalamic-Pituitary-Adrenal Axis
Our brain is busy and promotes efficiency. Therefore, when it comes to stress, the brain consolidates, simplifies, and anticipates any remote memory of fear or threat. The primary system for regulating the effects of stress on the body is the hypothalamic-pituitary-adrenal (HPA) axis (Figure 2.3). When the limbic system sends a message of fear or threat to the hypothalamus, it releases a hormone called corticotropin-releasing factor (CRF) in reaction to the stress. This CRF stimulates the pituitary gland, which then releases adrenocorticotropic hormone (ACTH), and in turn ACTH stimulates the adrenal glands to release cortisol.
Cortisol is just one of the hormones produced by the adrenal glands. These triangular glands, which sit atop the kidneys, have two parts: an outer part called the adrenal cortex and an inner part called the adrenal medulla. The outer part produces hormones that are essential to life; for example, cortisol, which regulates metabolism and helps your body achieve homeostasis, as well as aldosterone, which helps to regulate blood pressure. The inner part of the gland produces the body’s nonessential hormones, including adrenaline, which helps the body adapt to stress. Too much (or too little) of any of these hormones is not a good thing, but too much of the essential stress hormone cortisol can be especially damaging, because it causes a cascade of detrimental effects throughout the body.
When overt and/or covert stress acts on the brain, the autonomic nervous system's sympathetic ("gas") or parasympathetic ("brakes") divisions are affected. Activating the sympathetic nervous system changes the body's concentration of adrenaline and cortisol, which are hormones produced by the adrenal glands above the kidneys. When stress acts on the brain, the hypothalamus and pituitary gland direct the adrenal glands to increase adrenaline and cortisol production.
How Stress Affects Our Health
As a physician, I realize that quantifying stress is extremely difficult and requires a lot of detective work because each of us perceives stress differently. We need to look at both external (psychosocial factors) and internal (inner dialogue, unrealistic expectations, and mindset) stressors. Simply stated, some people have overt stress, which seems obvious to others, such as financial hardship, broken relationships, a demanding job, physical pain, or struggles with loneliness. Others have covert stress, which is not clear to others and sometimes not clear to themselves. They have a healthy marriage, financial security, a wonderful house, and regular vacations, yet they develop unseen stress ulcers or drop dead of a heart attack. Put another way, during prehistoric times, we regularly ran away from real-life predators like saber-toothed tigers (overt stress). Now we keep trying to run away from “internal” tigers, such as fears of rejection, loneliness, abandonment, and failure that roam our minds (covert stress). Negative thoughts and beliefs, including an illness mindset, produce a covert stress reaction in the body that has the same effect as overt stressors. So be very aware of the thoughts you think and the beliefs that run your program because they contribute greatly to your health. There could be a covert operation sabotaging your health!
We also need to look at people’s adaptive techniques or soothing behaviors to neutralize stress and understand how they were formed. Our brains are wired for social interaction; for example, newborns learn that to acquire food they must communicate and interact with people around them. They may learn that crying results in food, whereas soft cooing is a way to obtain hugging and caressing. This early conditioning primes how our brain forms the neural circuits, or thought patterns, that process information about the world and our surroundings. When love, connection, and safety are missing, human brains perceive this as a threat, which forms a neural pathway very early in development.
Emotional threats activate the gas, yet we are mostly unaware that our subconscious thoughts are producing stress hormones even without an apparent external stressor. Having mostly adverse childhood experiences sets up neural pathways for a negative inner dialogue and a lack of soothing behaviors. For example, infants can sense when there is a lack of affection, bonding, and nurturing, which can set them up to feel neglected as adults. And children who experience verbal or physical abuse and trauma are at higher risk for disease in their later years. Their neural wiring is being set early on for anxiety, worry, and a “reactive” nervous system. In contrast, infants who are held and caressed and feel love with human touch thrive better. That relationship stability in the early years helps create a sense of security and belonging that develops neural networks that are more conducive to health and fostering better relationships.
We know that stress can show up in different forms—emotional, physical, environmental toxins, infections—but the bottom line is that an endless supply of stress hormones, no matter what their source, damages our body. When we experience chronic stress, the ANS gets stuck in the gas mode and it’s like having your “pedal to the metal.” Our body was not meant to be in a perpetual stress