Charles Russo M.D., FACCIn the first part of this series we learned about the "fight or flight" response which is involuntary and leads appropriately in situations of stress to enhancing our survival by increasing our heart rate, breathing rate and blood pressure while diverting blood from noncritical functions and organs to more critical functions and organs such as the heart, lungs, muscle and brain and increasing our mental acuity and short-term memory. All of this helps us in a short term crisis.
What problems can arise from the stress response? If it was meant to help us survive are there circumstances when this is not beneficial? In general, the stress response was meant to be a short-term response to an immediate threatening situation. Whether in the animal kingdom or among other primates if this stress response is turned on to frequently and for too long a period of time it can have negative side effects.
What do I mean by that? Studies have shown that the response to acute stress with an increase in heart rate and blood pressure is sustained over longer periods of time with chronic stress. In addition, longer periods of stress and more recurrences without a return to a normal baseline in between can lead to chronic structural changes in the body such as changes in the blood vessels where they become thickened from the increased blood pressure which can lead to eye and kidney damage as well as an enlargement of the heart but the worst consequence of this is accelerated atherosclerosis or the fatty buildup on the inside of blood vessels from the constant bombardment by high blood pressure and faster heart rates. The shearing force on the blood vessel wall from this hyper-dynamic state is the cause.
In addition to the chronic elevation of stress hormones, such as adrenaline, there are also what are called glucocorticoids that aggravate this whole process. Glucocorticoids are hormones from the adrenal gland that promote the release of sugar into the bloodstream from the liver and also mobilize energy from fatty tissue. While this may seem beneficial at first, over the long term, this leads to insulin resistance and promotes the release from active fatty tissue of other hormones that are pro-inflammatory in the body and aggravate many other processes such as atherosclerosis. It was thought that fat tissue was fairly inert and inactive but, like many other concepts in medicine, we have to reevaluate this concept in light of new data it has been shown to be quite active not only locally but at a distance due to other hormones that it produces.
Chronic stress and the release of these hormones and the stimulation of the ANS can lead to a change in sleeping patterns and a decrease of REM sleep. Over the long-term this disruption in sleep pattern is a significant problem since it often leads to daytime fatigue and then many of the other symptoms related to depression may ensue. It is thought that this chronic sleep deprivation without significant patterns of normal sleep intervening helps to cause the depletion in the brain of dopamine and serotonin which may usher in chronic depression.
Appetite is also affected. Two thirds of people under stress will lead more because it is comforting. One third will eat less.
Now that we know our body's response to acute stress and what happens when this becomes a long-term issue with chronic stress we will be ready to explore in the next article how to try and understand what we can control about stress and, therefore, what we might be able to do about.
Charles Russo M.D., FACC, is Board certified in internal medicine and cardiovascular disease. He lives in Fort Lauderdale with his wife and 4 children and obtained his medical degree from New York Medical College with his Cardiology degree from the University of Miami and has advanced degrees in nuclear Cardiology and Lipidology (the study of blood fats).
