At the turn of the 20th century, most people in the U.S. died from bacterial or viral infections such as pneumonia, influenza and tuberculosis, according to the Center for Disease Control. The New England Journal of Medicine reported that cardiovascular diseases and cancer ranked as the top two leading causes of death in 2010. Even though most of these diseases can be prevented with diet, exercise and lifestyle changes, the root of these problems may likely be from chronic stress, the silent killer that many patients and medical professionals tend to overlook.
Chronic stress can increase the likelihood of mental illnesses, such as anxiety disorders and depression. According to the Anxiety and Depression Association of America, anxiety disorders are the most common mental illnesses in the U.S., affecting about 18 percent of the adult population – or about 40 million Americans. In fact, long-term mental illness of any kind can shorten longevity and increase the risk of getting cardiovascular diseases, gastrointestinal diseases and cancer.
Neuroscientist Robert Sapolsky, Ph.D., from Stanford University, is one of the leading experts on stress in the U.S. He states that humans have become smart enough to make themselves sick. During stress, hormones such as adrenaline and glucocorticoids, are released into the bloodstream, causing increases in heart rate and energy metabolism. From a biological and evolutionary standpoint, this is necessary for humans and other vertebrates to outrun or fight a predator that is about to rip them to shreds. Sapolsky wrote in Greater Good that such short-term stress is essential to survival, because energy is mobilized and delivered to where the body needs it the most, such as leg and hip muscles to run. Non-essential functions, such as growth, reproduction, and digestion are shut off while essential functions – immune system, memory, and learning – are enhanced. Once the stress stimulant is gone, the body reverts to its non-stressed state and carries on its normal functions.
But what happens among people with chronic stress? Because they cannot turn off the stress response, these people can suffer the consequences of stress for months or years, which can explain many diseases and disorders, such as erectile dysfunction, irritated bowel syndrome and stroke. Sapolsky mentioned that the stress response did not evolve to be turned on for a long time. “Do it regularly enough, and you’re going to damage your cardiovascular system,” he wrote.
Humans can turn on stress with emotions, thoughts, and memories, and by worrying about non-life-threatening stressors, such as 20-year mortgages and afternoon L.A. traffic on the 405. This can cause a chain reaction that leads to various “silent killers” that strike unexpectedly among those with chronic stress. “If you turn on the stress response chronically for purely psychological reasons, you increase your risk of adult onset diabetes and high blood pressure,” he warned. Shutting down the digestive system can also increase the risk of gastrointestinal disorders as well.
In a discussion that was published in Proceedings of the National Academy of Sciences, Sapolsky states that atrophy of the hippocampus in the brain, which is the part that associates with memory and learning, is common in people with post-traumatic stress disorder. So far, it is not yet known whether stress really is directly causing it to atrophy. If so, can the process be reversed? Sapolsky also wonders if having a small hippocampus can make people more vulnerable to stress. “There is evidence for both sides,” he mentioned. What is currently certain is that learning to manage and coping with stress is the first line of defense against most silent killers.
By Nick Ng