New knowledge prompts researchers to investigate better methods of decreasing stress levels
“When I get stressed, I get headaches, have trouble sleeping, and crave sugary food, which makes my headaches worse and causes even more stress. It becomes a vicious cycle,” Laura Grant, a College of Communication sophomore at Boston University, said.
Until recently, researchers believed people’s response to stress was a primal reaction, similar to those found in other animals. In a new study published in Scientific American, Yale researchers Amy Arnsten, Carolyn M. Mazure and Rajita Sinha have discovered humans’ response to stress is more than just a primal reaction.
Stress can “cripple our most advanced mental faculties” in the most developed parts of the human brain, according to the study.
For years, scientists believed the hypothalamus, which is located toward the base of the brain and is one of the oldest brain developments in primates, played the primary role in stress reaction. When engaging in stressful situations, the hypothalamus triggers the release of hormones from the pituitary and adrenal glands, causing elevated heart rate and blood pressure and decreased appetite.
This new study now demonstrates the prefrontal cortex, the most highly evolved part of the brain, plays a bigger role in stress reaction than once thought. This new revelation has prompted researchers to investigate behavioral and pharmaceutical treatments to control the negative cognitive effects of stress.
THE PREFRONTAL CORTEX
The prefrontal cortex is responsible for some of the highest cognitive abilities humans have, including concentration, decision-making and judgment. It inhibits inappropriate thoughts and actions and contains the neural circuitry necessary for abstract thought, attentiveness and temporary memory storage. Under non-stressful conditions, the prefrontal cortex serves as a “control center” that regulates these mental processes, emotions and impulses.
While the prefrontal cortex serves many important functions, it is extremely sensitive to everyday anxieties, both mild and severe. In the study, acute stress signaled a series of chemical reactions that weakened the prefrontal cortex’s control, which is based on an internal network of connections among neurons called pyramidal cells.
These triangular shaped neurons connect to other parts of the brain that control emotions, desires, and habits. Stress, however, can weaken these neuron connections, consequently empowering other control centers, including the hypothalamus. When this happens, we feel inclined to indulge in habits the prefrontal cortex generally controls, Amy Arnstern, the lead researcher of the Yale study, said in a phone interview.
“You can end up with real structural changes in your brain where you are less regulated by these higher order prefrontal systems and more controlled by primitive unconscious systems, like the amygdala,” Arnstern said. “You can get into very bad habits in terms of drug abuse, alcohol abuse, mindless overeating.”
WHAT HAPPENS DURING STRESS
Stress signals the release of arousal chemicals, such as norepinephrine and dopamine, which are transported from the brain to the brain stem through neurons. When levels of these chemicals are high, the prefrontal cortex shuts off neuron firings by temporarily weakening the connection between them.
As a result of decreased network activity, the ability to regulate behavior decreases. This lack of control worsens as the hypothalamus commands adrenal glands near the kidneys to disperse the stress hormone cortisol into the bloodstream and to the brain.
While the prefrontal cortex is responsible for a great deal of human functions, other parts of the brain control human behavior. For instance, when dopamine hormones reach the deep-brain area structures called the basal ganglia, they regulate appetite and control habitual emotional, as well as motor responses.
Studies in 2001 by Benno Roozendaal, James McGaugh and their colleagues showed how this reaction was found in the amygdala, which prepared itself for danger in the presence of cortisol and norepinephrine. These hormones signaled the nervous system to prepare itself by recollecting memories of fear.
This research, originally analyzed in animals, translates to human reactions to stress in the prefrontal cortex. In humans, dopamine and norepinephrine are released and switch off prefrontal cortex circuits necessary for higher cognition. There are enzymes in the brain that generally “chew up” neurotransmitters so that this shutdown does not continue so we can return to normal when stress subsides. However, sometimes these enzymes do not work properly, and the effects of stress, as a result, persist.
The effects of stress, and particularly chronic stress, make us more vulnerable to additional stress, depression, addiction and anxiety disorders throughout life. However, it is difficult to conduct further studies testing researchers’ hypotheses about stress. It is generally considered unethical to expose subjects to periods of extreme psychological stress.
WHY WE STRESS
Scientists are now wondering what the biological purpose of stressing is. Why have humans evolved with this adaptation if it has such negative effects on humans? While scientists have no concrete answers to these questions, they have theorized that stress is a survival mechanism.
The triggering of primal reactions may have saved ancient human lives in times of danger, such as in confrontations with wild predators. These mechanisms, according to the study, may serve an important function in the modern world, where your brain may signal you to slam on the brakes upon being cut off by a reckless driver.
“In modern life, especially in cities like Boston, you forget that nature, and even people, can be those dangers,” Arnstern said. “You wouldn’t want your brain to have forgotten how to survive.”
Arnstern said genetics may play a role in stress. Some people are more vulnerable to stress due to their genetic makeup, in which a particular form of a gene can weaken the enzymes that “chew up” neurotransmitters in the brain.
Gender seems to play a role in stress vulnerability. In women, for instance, estrogen may make them more sensitive to stress, rendering them more susceptible to depression than men. Genetics aren’t the only thing that makes people more sensitive to stress than others. Environmental factors may play a key role in stress vulnerability.
Jake Cox, a School of Management sophomore, said BU students get stressed due to school work.
“I get stressed when things pile up. I finds it difficult to manage a bunch of projects at once,” Cox said.
SOLUTIONS TO STRESS
Researchers are devising ways to assist the prefrontal cortex’s regulation of stress reactions. These consist of both pharmaceutical and behavioral therapy methods.
The drug prazosin, for instance, is a generic therapy for blood pressure that blocks some the negative impacts norepinephrine’s has on the brain. It is currently being tested on patients with post-traumatic stress disorder, such as veterans. Another study recently conducted by Yale associate professor Sherry McKee of Yale and her colleagues found that guanfacine, another generic medicine for blood pressure, can decrease certain stress reactions and help the prefrontal cortex’s regulation of stress.
Aside from medicine, behavioral strategies to manage stress are being researched. These include relaxation, cognitive behavior therapy, meditation and deep-breathing strategies. However, Arnstern said, methods of treatment depend on the individual’s needs.
“Some people they’re able to do cognitive behavior therapy, and it helps them to stop bad habits and become healthier,” she said. “For other people, they don’t have the prefrontal cortex to even begin, and they’re needing a pharmacological intervention to give them enough prefrontal cortex back on line to begin help themselves in other ways.”
A number of BU students made suggestions on how to manage their stress.
“I go to the gym to alleviate stress during a busy week,” Cox, a SMG sophomore, said.
Others suggest taking a breather from time to time may help.
“I try to make time for myself, even when I have a lot of work to do,” Grant, a COM sophomore, said.
However, Arnstern said she believes the best for students to manage daily stress is by helping themselves.
“The most important thing is to help yourself feel in control,” she said. She suggested exercise, relaxing walks and formulating schedules for yourself. Furthermore, she suggested ways to calm yourself in times of stress.
“If you’re taking a test or you’re trying to study and your mind’s going blank,” she said, “just think ‘this is just my stress physiology, I just need to relax a little bit. It’s going to be okay.’”
For more Science Tuesday check out our blog this week: http://freepblog.wordpress.com/2012/04/30/who-are-you-talking-to-when-you-talk-to-yourself/