Feb 17, 2012
By Lizzie Roberts
Every time you’ve gone a full day without eating until dinner, had three tests on the same day, been barraged by seemingly endless bills, or been chased down by a pride of ravenous lions, your brain has reacted by secreting hormones that tell your body to kick it up a gear. While stress can sometimes be a useful motivator in the short-term — e.g. running away from an out-of-control car or cranking a paper out the night before it’s due — in the long-term, chronic stress can have detrimental effects on both your body and mind.
In the early days of the Homo sapiens, when our ancestors primarily traveled in nomadic groups and hunted their own food, the individuals who were most likely to survive were those with more responsive stress systems. Overreacting to a rustle in the bush and passing up potential food was better than walking into a predator — opportunities are somewhat more difficult to come by when you’re dead. There were certain survival strategies that proved to be especially advantageous, such as maintaining environmental and social stability. Those individuals whose brains triggered an unpleasant red alert when they did not follow these strategies were more likely to correct their behavior, thereby increasing their chances of surviving and reproducing. Thus, over the course of thousands of years, the stress response evolved to warn an animal that a threat was present in the environment, and to produce changes in body function that would give him the best shot at weathering the storm.
There are three general categories of stressors: acute physical, chronic physical, and chronic psychological/social. Acute physical stressors are threats that trigger the famous ‘fight-or-flight’ response: a rush of epinephrine, aka adrenaline, released by the adrenal glands that rest on top of your kidneys. Crossing the street and almost getting flattened by a coked-out motorcyclist would provoke an acute physical stress response. A chronic physical stressor puts direct strain on your body, but occurs over a much longer time period — a famine or drought, for example. A chronic psychological/social stressor cannot physically harm you, but is still perceived as undesirable — or even painful — stimulus. A boss who’s in serious need of anger management therapy and constantly criticizes you is a good example of a chronic psychological stressor.
* * *
One of the major issues with the body’s stress response is that your brain is not very good at distinguishing between these different stressors, particularly chronic physical and chronic psychological; it reacts in a similar fashion whether you’re going hungry or writing three dissertations on Anna Karenina. Our chronic stress response evolved to be excellent at coping with physical stressors because the more commonly encountered threats to our primate ancestors were a) not having enough food, water, or shelter, and b) physical attack. In the midst of a famine, the body had to be able to switch into a long-term operational mode that allowed it to divert energy to only the most necessary biological functions, like providing food for the brain. In the case of physical attack, your body had to function at top capacity for hours at a time. While the modern human body is still equipped to deal well with these physical stressors, its responses are not always appropriate to cope with chronic psychological stressors. Diverting attention from building new bone makes sense when you need all your energy to fight a war, but not when you’re in the middle of finals week. Stress can become chronic when psychological stressors crop up more frequently than physical stressors, as they do in some parts of the world today, because the brain reacts to these perceived threats in the same way it would react to physical threats.
The long-term stress response in humans involves a class of steroid hormones known as glucocorticoids, the most important of which is cortisol. Glucocorticoids are secreted by the adrenal cortex, the outside ‘rind’ of the adrenal gland. Cortisol changes how your body functions by affecting which DNA gets transcribed into mRNA in your cells, thereby controlling which proteins and other gene products your body creates. It is released in response to all three types of stressor, but its effects and duration of secretion vary according to the situation. Its changes might only last for fifteen minutes during an acute physical stressor, while a chronic psychological stressor may cause alterations that endure for years. By comparison, the effects of the “fight or flight” response usually stick around only a few minutes.
Your body’s responses to cortisol aren’t entirely detrimental; in fact, glucocorticoids are extremely important for maintaining the homeostasis of several crucial systems in the body. For example, cortisol is secreted daily by your brain shortly before you wake up, and continues to be secreted after you get out of bed in order to provide you with a pre-breakfast energy boost. The danger of glucocorticoids is when your body fails to recognize a period of stress is over, and continues to divert its attention to coping with an adversarial environment. Your body continues to release glucocorticoids, and over time the hormones begin to have adverse effects.
One of the biggest dangers of glucocorticoids is that at high, chronic levels they can actually cause damage to their own regulatory systems. The hippocampus, a region of the brain crucial for memory formation and stuffed with glucocorticoid receptors, normally exerts negative feedback on the production of glucocorticoids. When the hippocampus is inundated with cortisol, it sends a signal to the hypothalamus to stop producing the corticotropin-releasing hormone (CRH) that stimulates glucocorticoid production. Long-term exposure can eventually cause damage to hippocampal neurons. Thus, the longer you remain clamped in the iron jaws of chronic stress, the greater the possibility that your ability to manage that stress will be impeded.
* * *
So what can you do to reduce your glucocorticoid levels during times of stress? A number of studies have been conducted with humans and non-humans to determine which factors mitigate the volume of glucocorticoids released in reaction to a stressor.
Firstly, even if you don’t have full control over a situation, finding something that makes you feel like you have some leverage may reduce your anxiety. A perceived sense of control over the stressor appears to correlate with significantly lower glucocorticoid release in rats, dogs, primates, and humans (e.g. being able to press a button to avert unpleasant stimuli). Loss of this control elicits a rise in glucocorticoid levels.
Along the same vein, if you can identify any signal which indicates the end of a stressful time, or learn to recognize what kinds of incidents tend to trigger your anxiety, you may find it easier to relax during times when neither indicator is present. A decreased glucocorticoid response is noted if a rat is able to predict the onset or termination of a mild electrical shock. Examples of this include reminding yourself that you can take a long nap once this test is over with, or recognizing that public speaking makes you want to curl up in the fetal position, and mentally preparing yourself for your body’s reaction.
Making sure you spend enough time with close friends and family can also be beneficial. Having a set of protective relationships has been shown to be an extremely effective modulator of the stress response, particularly in primates and humans. Additionally, having an outlet for frustration — such as exercise — has been shown to decrease glucocorticoid levels in rats, dogs, primates, and humans. Some studies have shown that animals under stress without proper frustration outlets are more likely to seek out a third party to exert aggression against.
Try to cultivate a positive outlook on whatever situation you find yourself in. There is a chemical basis for the usefulness of optimism: a larger stress response is observed in primates and human volunteers who believe that a situation is getting worse, as opposed to improving. Human parents whose children were in cancer remission with a 75% chance of surviving had near-normal glucocorticoid levels — an unexpected phenomenon possibly explained by the fact that not too long ago, that survival rate had been significantly lower.
The substances you consume can also have an effect on your mood and stress levels. Excitatory substances, such as caffeine, have been shown to increase human glucocorticoid levels. Constant high blood sugar can be wearing on the hippocampus in the long term; avoiding sugary drinks, excess bread, and cookies can help mitigate this response. Consuming omega-3 fatty acids (present in fish oils) may promote neuronal growth and mood elevation. One study has even suggested that eating comfort foods reduces glucocorticoid levels by a small amount.
Finally, meditation can be an excellent way to alleviate the stress response. Recent studies have shown that it can actually have physical effects on brain structure. Regular meditation has been shown to increase grey matter in the hippocampus, and prefrontal cortex. It improves psychological functions associated with cortical regions, such as attention, compassion, and empathy. Meditation additionally increases activity in the left frontal cortex (associated with mood lifting), decreases cortisol levels, strengthens the immune system, and positively affects a number of conditions (including cardiovascular disease, type II diabetes, PMS, chronic pain, insomnia, and anxiety). Meditation can be undertaken in many different ways — sitting, standing, even walking or swimming. The best results are obtained by keeping a daily practice, whether for one minute before bed or an hour in the morning.
Everybody’s stress response is different. A person’s anxiety levels rely on many more factors than how many glucocorticoids their kidneys secrete — mood and personality are extraordinarily complex phenomena that arise from the interactions between your entire brain and your entire body. However, there is an observed correlation between high glucocorticoid levels and high anxiety levels, and it is worth understanding how this system works in the hopes of learning how to consciously regulate it. Whether or not you believe in a higher power or human soul, it is undeniable that the mind and the body are intrinsically linked to one another. Putting any extraneous substance into your body can cause a change in your mental state, whether it’s the buzz of a sugar high or the rush of an ecstasy tablet. Why should endogenous chemicals be any different?
* * *
We are not invincible beings, and our brains are always developing new connections and withering away old ones. These fleshy, wrinkled blobs retain a remarkable capacity to change themselves throughout adulthood, for better or worse. We must take that ability seriously, and understand that the way we treat our bodies and minds now may have unforeseeable consequences down the road. Though we all have many responsibilities to juggle, it is worthwhile to take time out of our busy schedules to relax, play, and remind our wearied brains that many of these perceived threats are just that: perceptions, unable to cause us real physical harm.