Effects of Stress on Memory in Medical Students


Where Does My Stress Come From? It doesn’t take much to stress out the average human being. When we view a situation as threatening, we become anxious and stressed. In prehistoric times, when evolution developed our biological response to threats, such as large predatory cats with huge canines, we reacted with extreme perspiration, rapid heartbeat, and dry mouth. Our bodies also directed blood flow away from the brain and extremities to the major organs. These were all sensible adaptive mechanisms. Today, the nearest thing to a true threat in our environment is a speeding bus that almost hits us at an intersection.


Today, our current perceived threats and resulting anxieties have taken a complete shift. Medical student stressors typically consist of worry over perceived low grades, disappointing a supervisor, or not doing well on an interview. These are hardly life-threatening events, but still create the same biological response imbedded in our genetic programming, as we view these events as threatening to our ego, personal identity, and future career plans.


When our brains see something as threatening, we respond with sympathetic releases of cortisol and glucosteroids that affect our blood pressure, heart rate, and blood flow. (for more about cortisol and stress see http://stress.about.com/od/stresshealth/a/cortisol.htm)


Equally important is the release of catecholamines (epinephrine, norepinephrine, and dopamine) and Neuropeptide S. The Neuropeptide S is a stress modulator in that it decreases sleep and increases alertness and a sense of anxiety and urgency in situations in need of escape. If you were trying to outrun that Sabertooth kitty right now, you would be screaming for an overload of this protein.


The Biology of Stress Effects on Memory. Those catecholamines released during the onslaught of stress and anxiety also suppress activity in areas at the front of the brain responsible for short-term memory, concentration, inhibition and rational thought. It is this series of mental events that allows a person to react rapidly to a threatening situation – the classic “fight or flight” choice we commonly hear about. The highly stressed individual operates mainly on instinct at this time, and the release of these neurotransmitters interferes with the ability to handle complicated social or intellectual tasks and behaviors (like those needed for higher education problem solving).


Robert M. Sapolsky, renowned brain researcher, has shown that sustained stress can damage the hippocampus, which is central to learning and memory. The offenders are "glucocorticoids," (aka. corticosteroids or cortisol) secreted from the adrenal glands during stress. He showed that during a perceived threat, the adrenal glands immediately release adrenalin. If the threat is severe or still persists after a couple of minutes, the adrenals then release cortisol. Once in the brain cortisol remains much longer than adrenalin, where it continues to affect brain cells. Chronic over-secretion of stress hormones adversely affects brain function, especially memory. Too much cortisol can prevent the brain from laying down a new memory or from accessing already existing memories. This is particularly important for medical students for two reasons: (1) the amount of information they are required to learn is demanding, and (2) the expectations on time, performance, and dedication is high over several years. These two factors in combination form a situational environment to create sustained stress and lead to chronic over-secretion of stress hormones.


One of the most common challenges for medical students is adjusting and developing their test-taking abilities. Many students develop what is commonly known as the "Imposter Phenomenon." Under this, students often experience concern that they study and study the night before a class, but struggle with retaining their readings and preparations. They commonly fear there is something seriously wrong because their high school and undergraduate schooling was relatively effortless for them. They are studying harder and learning less. When exams approach, they blank out and struggle to remember information that would allow them to make proper decisions on their tests. All of a sudden, they are not "good test-takers"--an unnerving problem not countered before.


On the other hand, during extreme stress, neurotransmitters signal the hippocampus (a nearby area in the brain) to store the emotionally loaded experience in long-term memory. This neurocognitive action would have been essential for survival in prehistoric times, since long-lasting memories of dangerous events (such as how to avoid being eaten by an overgrown cat with abnormally large canines) would be essential for avoiding such threats in the future. So what does this mean for your long-term memory? Does that mean that students will remember anatomy better if a huge animal attacks them the night before their final exams? Probably not. Remember, it seems that the catecholamines are interfering with higher order thinking. Any long-term memory increases may be related only to the specific event and may be limited to emotionally loaded events.

It has also been found that individuals experiencing moments of extreme anxiety, such as during medical school examinations, often hyperventilate. Research also proposes that those who suffer chronic anxiety and stress responses over time are prone to shallow breathing, which more easily engages the flight or fight response.  During hyperventilation, confusion is not unusual and retrieval of learned information and concentration is compromised. In addition, nausea, dizziness, and other uncomfortable symptoms can distract you from performing your best during exam time. By staying aware of the symptoms and the possibility of chronic hyperventilation, you can improve your memory, concentration and recall simply by learning how to engage your relaxation response. (keep reading)

For a description and explanation of counteracting the shallow breathing and inducing a relaxation response with proper breathing, go to this link: http://www.anxieties.com/panic-step4.php

Counteract Stress Effects: Our physiological response to perceived threats (stress) is a biological response that is easily engaged. We refer to the flight or fight response discussed above. However, the opposite response to physically and emotionally calm ourselves is something we must learn to engage and is more commonly referred to as the relaxation response. This is a term coined by Herbert Bensen, MD and it involves learning to engage the parasympathetic nervous system through deep diaphragmatic breathing, progressive muscle relaxation, visualization, meditation and other calming techniques. (To read about Dr. Bensen and the relaxation response go to this link: (http://www.massgeneral.org/bhi/basics/rr.aspx ) or  http://2learnmeditation.com/relaxation-response.html


Learning to induce a relaxation response in a few minutes or a few seconds takes some practice and commitment. You cannot learn to do deep breathing and progressive muscle relaxation one day and then elicit a relaxation response within two minutes the following day or even in a few weeks. But it is well worth taking 15-30 minutes of training a day when you are finally able to engage your parasympathetic system at will and counteract the negative effects of stress and anxiety.


Learning Deep Breathing for Relaxation is the first step to a learning a complete relaxation regimen. It should include visualization and/or progressive muscle relaxation exercises until you can elicit a relaxation response by thinking of cue words or doing a quick “body check” for tense muscle groups.


Progressive Muscle Relaxation is a means to de-stress and cope with anxiety. As with deep breathing, PMR takes practice to elicit a relaxation response to counteract the flight or fight response initiated by stress or anxiety. This is a link to a site that describes one version of PMR. http://www.guidetopsychology.com/pmr.htm


Audio and visual relaxation guides are very useful to help you relax when you are very stressed from work and studying. Try this video from YouTube to help you find peace and calm at the end of a busy shift or before an exam when you want to “unblock” and open up cognitive pathways.  http://www.youtube.com/watch?v=Zh-klfBJlHc

Therapists will often develop guided meditations and relaxation scripts for specific situations such as helping a person to fall asleep, reduce chronic pain, or improve self-esteem. An example of a specific meditation by Dr. Bensen is found here: http://2learnmeditation.com/guided-meditations.html

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