Stressed or Sick? Body Gives Same Answer
Stressed or Sick? Body Gives Same Answer
By Jamie Talan
Staff Writer
The fever, aches, and pains that knock out millions of humans a year have long been blamed on the common cold and other infectious bugs. But university of Colorado psychologists believe that the stress may also trigger the same symptoms that have become synonymous with infection.
Steven Maier and Linda Watkins have found intriguing evidence that the body’s immune system, called upon to fight off bacteria and viruses, is tightly connected to the same pathways as the body’s stress system. They think that many people may be worrying themselves sick.
“We call these symptoms- fever, sleep difficulty, behavioral changes- sickness, but we think that these changes are highly adaptive,” Maier said. “When people are sick or even feeling in a depressed mood, the body needs to save energy.” To fight infection, slowing down allows available energy to drive up the body’s temperature, which in tern kills the infectious organism. With stress, the body needs to temporarily shut down to save up its energy store, in case there is a fight-or-flight situation.
Maier and Watkins have traced the immune pathways in both stress and sickness and found that they travel on the same bi-directional biochemical route. With and infection, immune system microphages are armed to attack the bug and signal the brain that there is an invader. The brain sets many things in motion. Chemicals are sent to the brain to increase body temperature, slow us down, make us sleepy, ect. “It turns out that these same immune circuits are activated during stress, which means that people can experience the same flu-like symptoms,” Maier said.
The psychologists say that the stress response came along millions of years after the immune system had been doing its job to fight infections. Even such primitive organisms as sponges and sea slugs show an immune response to infection. These same creatures lack a parallel fight-or-flight response. Because the stress responses also requires energy, scientists believe it just co-opted the same immune system mechanism.
In seeking to prove their theory, they put animals under stress and were able to measure a fever 45 hours later. “We’ve also seen primed microphages five days after the stressful event,” Maier says. He believes the immune system needs to be ready in a stressful situation just in case the person gets hurt.
The mechanism that evolved was probably in place since caveman faced predators- an acute stress- but Maier and Watkins dont believe that the human brain has yet evolved to handle chronic modern-day stress. “Our environment has changed much more than our genes have,” Maier says.
He says the day-to-day variability of human mood, behavior and cognition is driven by events in the immune system, and he hopes to prove it in his laboratory. He believes that bad moods are adaptive, not abnormal. It’s just part of the daily balance to conserve energy. But having one system for two different jobs clearly has its downside. Many people with physical illness- for instance, arthritis, lupus, and multiple sclerosis- complain of depression and loss of concentration. This may be one reason why.