Adrenaline, or epinephrine, and cortisol, or hydrocortisone, are stress hormones secreted from the adrenal glands, which sit above the kidneys. Though both chemicals are stress hormones, adrenaline and cortisol play different biochemical roles. Adrenaline primarily binds to receptors on the heart and heart vessels. This increases heart rate, force of muscle contraction and respiration. Cortisol binds to receptors on the fat cells, liver and pancreas, which increases glucose levels available for muscles to use. It also temporarily inhibits other systems of the body, including digestion, growth, reproduction and the immune system.
Adrenaline and cortisol normally are secreted in response to a perceived threat in the environment. The effects of stress hormones on blood glucose, heart rate and respiration increase oxygen and nutrient supplies to muscles and temporarily shut down the maintenance of the body's other systems. This so-called fight-and-flight response to perceived environmental threats gives organisms an evolutionary advantage in making them better able to survive by increasing their chances of either destroying the threat or escaping.
"Chronic stress" is an umbrella term that refers to continuous physical or psychological forms of tension and pressure. Chronic stress is directly linked to chronically high blood concentrations of adrenaline and cortisol. Even physical conditions such as long-term exposure to noise can cause prolonged high levels of stress hormones, even when the noise does not annoy people, reports a research team in the November 2005 issue of "European Heart Journal." The team examined medical files of people hospitalized for heart attack and found that chronic noise increase the risk of heart attack by up to 50 percent by increasing stress hormone levels.
Prolonged high levels of stress hormones increase the risk of heart disease, heart attack and stroke and may lead to structural alterations in the brain's memory and fear processing centers. High levels of stress hormones also make it easier for cancer to spread, reports a research team in the April 2010 issue of "Journal of Clinical Investigation." Normal cells that become detached from tissue quickly die off. Cancer cells, however, are protected from cell death in the presence of the protein FAK. The researchers found that adrenaline activates FAK, allowing more detached cancer cells to survive until they can reattach in a different region.
Treatments for prolonged high levels of adrenaline and cortisol include beta blockers and anti-anxiety medications. Beta blockers compete with adrenaline for the receptors on the heart and smooth muscles of blood vessels. But unlike adrenaline, beta blockers do not stimulate the adrenaline receptor. They just prevent adrenaline from binding to it. Beta blockers thus can prevent heart conditions that arise from prolonged high levels of stress hormones. Anti-anxiety medications such as selective serotonin reuptake inhibitors--for example escitalopram--may lower blood concentrations of stress hormones by eliminating the trigger.
The best prevention of prolonged high levels of stress hormones is to take stress seriously and seek immediate treatment. Many stress-inducing factors are beyond people's immediate control, however, including--to some extent--where they live and where they work. Factors beyond our immediate control include unexpected emotional events, which can lead to a sudden extreme surge in stress chemicals, according to a study published in April 2009 issue of "American Journal of Cardiology." The researchers found that sudden extreme surges in stress chemicals triggered by negative emotional events can give rise to stress cardiomyopathy, a life-threatening but reversible condition in which the heart muscle is temporarily weakened or stunned.