Stress
Unremitting stress damages the immune system. Two years ago, researchers at UCSF looked at white blood cells from a group of mothers whose children suffered from chronic disorders like autism or cerebral palsy. They found clear signs of accelerated aging in those study subjects who had cared the longest for children with disabilities or who reported the least control over their lives.
The changes took place in microscopic structures called telomeres, which are often compared to the plastic wrappers on the ends of shoelaces and which keep chromosomes from shredding. As a general rule, the youngest cells boast the longest telomeres. But telomeres in the more stressed-out moms were significantly shorter than those of their counterparts, making them, from a genetic point of view, anywhere from nine to 17 years older than their chronological age.
People with low self-esteem are more vulnerable to stress. According to Jens Pruessner, the hippocampus — a finger-size structure located deep in the brain, which helps you form new memories and retrieve old ones — is particularly sensitive to the amount of cortisol flooding your cerebrum. So when cortisol levels begin to rise, the hippocampus sends a set of signals that help shut down the cortisol cascade.
Using several different types of brain scans, Pruessner has shown that people who test below average on self-esteem also tend to have smaller-than-average hippocampi. (The differences become clear only when you compare groups of people.)
Samuel Melamed: “[I]f there is no relief [from stress] and the cortisol stays up for long periods of time, the body stops responding and readjusts the level.”
If you provide mice with an escape route, they typically learn quickly how to avoid a mild electrical shock that occurs a few seconds after they hear a tone. But if the escape route is blocked whenever the tone is sounded, and new shocks occur, the mice will eventually stop trying to run away. Later, even after the escape route is cleared, the animals simply freeze at the sound of the tone– despite the fact that they once knew how to avoid the associated shock.
Animal research has shown that there is a relatively small window for reversing the physiological effects of chronic stress. And once a person’s cortisol level gets completely blunted, it may stay that way for years.