"Apparently, high levels of cortisol, a stress hormone, predict brain function, brain size, and performance on cognitive tests," said study lead author Dr. Sudha Seshadri and professor of neurology at the University's Science Center. University of Texas at San Antonio.
"We found that memory loss and brain shrinkage can be noticed in relatively young people long before the symptoms are noticed," Seshadri said.
Too much to fight or run away from.
Cortisol is one of the major stress hormones, best known for its intervention in the "fight or flight" instinct. When we are stressed or on alert, the adrenal glands produce more cortisol. The hormone causes the suspension of various bodily functions that may interfere with survival.
Once the crisis has passed, cortisol levels should subside and body systems should return to normal. But if your alarm button is pressed, the body can continue to malfunction, causing anxiety, depression, heart disease, headaches, weight gain, sleep problems and of course memory problems and concentration.
According to experts, the brain is particularly vulnerable because of the amount of nutrients it needs to function properly.
"The brain is a very hungry organ," said Keith Fargo, director of scientific and contact programs at the Alzheimer's Association. "It takes a huge amount of nutrients and oxygen to continue to function properly, so when the body needs these resources to deal with stress, there is less to send to the brain."
Intense stress is related to memory loss
In previous studies, a relationship was found between cortisol and the risk of developing dementia; however, studies have focused on the elderly and the area of the brain in which the memory resides, called the hippocampus.
Among the advantages of the new study, according to Seshadri, is that a group of 48-year-old men and women were analyzed on average and MRIs were performed throughout the brain, not just the hippocampus.
The researchers chose more than 2,000 people who showed no signs of dementia and applied various psychological tests to assess their cognitive abilities.
All were part of the Framingham Heart Study, a long-term study sponsored by the US National Heart, Lung, and Blood Institute. The study looked at the health of residents of Framingham, Massachusetts – and their children – since 1948.
The group was reassessed about eight years after the initial tests. Cortisol in the blood was measured before breakfast. Then MRIs were made and memory and cognition tests were repeated.
After adjusting the data according to age, sex, body mass and smoking, it was determined that people who had the highest levels of cortisol had the greatest memory loss.
"I was not surprised by the change in cognition," said Fargo, who was not involved in the study. "If you have a higher level of cortisol, you are probably stressed and probably have more difficulty with cognitive tests."
Stress also affects the structure of the brain
Fargo noted that what was surprising was what was discovered about the effects of cortisol on the structure of the brain.
High levels of cortisol have been associated with greater damage to parts of the brain that move information through the organ (radiant corona) and between the hemispheres (corpus callosum).
In addition, the study revealed that the part of the brain responsible for thinking, emotions, speech, and muscle functions was lower in people who had higher levels of cortisol.
The average brain volume of people who had high levels of cortisol was 88.5% of the total brain volume, as opposed to 88.7% of people with normal levels of cortisol.
"I was surprised that we could see such a big change in the structure of the brain with elevated levels of cortisol compared to moderate levels of cortisol," Fargo said. "If you notice structural brain changes in middle age, you can imagine what will happen when you are old enough to develop dementia."
Curiously, apparently, the effects of high cortisol on brain volume occur only in women, not in men.
"Estrogen can increase cortisol," said Richard Isaacson, medical director of the Alzheimer's Prevention Clinic at Weill Cornell University School of Medicine in the United States. "About 40% of the women in the high cortisol group in the study were on hormone replacement therapy." Isaacson did not participate in the study.
Seshadri said adjustments were made in the study that took into account hormone replacement therapy. "This does not completely rule out the adverse effect of hormone replacement," he added, "but it is less likely in this history."
Seshadri also emphasized that the results of the study show only a relationship, not a cause, and that more research is needed to determine the relationship between elevated levels of cortisol and dementia. He proposes that while this happens, people should think about making changes in their lifestyle to counter the stress of modernity.
Fargo agrees. "We know, for example, that people who exercise throughout their lives have a lower risk of developing dementia," he said. "Take time out for yourself, do meditation, there are always ways to control stress that will give you positive results."
With expansion information