"Obviously, high levels of abdominal muscle, stress hormone, predict brain activity, brain size and performance in cognitive tests," says Sudha Seshadri, Research Professor and Professor of Neurology at the University's Science Center. Health at San Antonio University in Texas.
"We found that brain memory loss and shrinkage may be observed in relatively young people long before symptoms can be detected," Seshadri said.
Too much to "fight or flee"
Cortisol is one of the most important stress hormones best known for its lack of fighting or flying. When we are stressed or warned, adrenal glands produce more cortisol. The hormone then causes a variety of bodily functions to suspend, which may interfere with survival.
When the crisis passes, cortisol levels should fall and body systems return to normal. But if the emergency button is pressed, the body may still be disturbed, causing anxiety, depression, heart disease, headaches, weight gain, sleeping problems and, of course, memory problems and concentration.
According to experts, the brain is particularly vulnerable due to the amount of nutrients it needs to function properly.
"The brain is a very hungry body," says Keith Fargo, director of scientific programs, and Alzheimer's association. "It requires a lot of nutrients and oxygen to keep up properly, so when the body needs these resources to treat stress, it's less transmitted to the brain."
Strong stress is associated with memory loss
Previous studies have shown the relationship between cortisol and dementia development risks; However, studies focus on the elderly and brain areas where the memory is, called the hippocampus.
According to Seshadri, the benefits of a new study are that the 48-year-old men and women group was analyzed on average and MRIs were performed throughout the brain, not just in the hippocampus.
Scientists chose more than 2,000 people who did not show signs of dementia and used a number of psychological tests to evaluate their cognitive abilities.
They were all part of Framingham Heart Study, a long-term research supported by the US National Heart, Lungs and Blood Institute. The study has analyzed the health of Framingham, Massachusetts – and their children's children – since 1948.
The group was re-evaluated about eight years after the first tests. Blood cortisol was measured before breakfast. Then magnetic resonances were made and memory and cognition tests were repeated.
When data were adjusted according to age, sex, body mass and smoking, it was determined that people with the highest cortisol levels were the biggest memory loss.
"I'm not surprised by cognitive change," said Fargo, who was not involved in the study. "If you have a higher cortisol, you are likely to be emphasized and you will probably have more difficulty in cognitive testing."
Stress also affects the structure of the brain
Fargo noted that it was surprising what was observed about the effects of cortisol on brain structure.
High levels of cortisol were associated with greater damage to brain parts that transfer information between the body (radiating crown) and the hemispheres (Corpus callosum).
In addition, the study found that part of the brains associated with thinking, emotional, speech, and muscle activity was smaller in people with higher cortisol levels.
The average brain volume of people with high cortisol levels was 88.5% of total brain volume, unlike 88.7% of people with normal cortisol levels.
"I was surprised that we could see such a big change in brainstem elevated cortisol concentrations compared to moderate cortisol levels," said Fargo. "If you notice structural changes in the brain in the Middle Ages, you can imagine what happens when you are old enough to develop dementia."
Interestingly, the elevated cortisol effect on brain volume occurs only in women, not in men.
"Estrogen can increase cortisol," says Richard Isaacson, MD, Medical Director of Alzheimer's Prevention Clinic at Weill Cornell University's Medical Institute in the United States. "About 40% of the women in the study in the high cortisol group were in hormone replacement therapy." Isaacson did not participate in the study.
Seshadri said that adjustments to the hormone replacement therapy study were made. "This does not completely exclude the side effects of hormone replacement therapy," he added, "but this story is less likely."
Seshadri also stressed that the results of the study only show a relationship, no reason, and that further research is needed to determine the relationship between cortisol and dementia. He suggests that when this happens, people should think about changes in their way of life against modern stress.
Fargo agrees. "We know, for example, that people who use their whole life have a lower risk of getting dementia," he said. "Take time for yourself, do meditation, there are always ways to manage the stress that will give you positive results."