How stress can affect your memory
Written by Dr. Manju Dewan   

One of the most basic behavioral differences between men and women is how they respond to stress. Men often react to stress with a "fight-or-flight" response, but women are more likely to manage their stress with a "tend-and-befriend" response. Females respond to stressful conditions by protecting and nurturing their young (the "tend" response), and by seeking social contact and support from others especially other females (the "befriend" response).


Stress can affect your mood, but it can increase the risk of stroke, hamper learning, suppress your growing network of brain neurons and weaken the protective blood-brain barrier.
Chronic over-secretion of stress hormones adversely affects brain function, especially memory. Too much cortisol can prevent the brain from laying down a new memory, or from accessing already existing memories. Sustained stress can damage the hippocampus, the part of the limbic brain which is central to learning and memory. The culprits are "glucocorticoids," a class of steroid hormones secreted from the adrenal glands during stress. They are more commonly known as corticosteroids or cortisol. During a perceived threat, the adrenal glands immediately release adrenalin. If the threat is severe or still persists after a couple of minutes, the adrenals then release cortisol. Once in the brain cortisol remains much longer than adrenalin, where it continues to affect brain cells.
Cortisol also interferes with the function of neurotransmitters, the chemicals that brain cells use to communicate with each other. Excessive cortisol can make it difficult to think or retrieve long-term memories. That's why people get confused in a severe crisis. Their mind goes blank because "the lines are down." Stress hormones divert blood glucose to exercising muscles, therefore the amount of glucosehence energythat reaches the brain's hippocampus is diminished. This creates an energy crisis in the hippocampus which compromises its ability to create new memories. That is why some people can't remember a very traumatic event, and why short-term memory is usually the first casualty of age-related memory loss resulting from a lifetime of stress.
Normally, in response to stress, the brain's hypothalamus secretes a hormone that causes the pituitary gland to secrete another hormone that causes the adrenals to secrete cortisol. When levels of cortisol rise to a certain level, several areas of the brain, especially the hippocampus tell the hypothalamus to turn off cortisol producing mechanism. This is the proper feedback response. The hippocampus, however, is the area most damaged by cortisol. Older people often have lost 20-25% of the cells in their hippocampus, so it cannot provide proper feedback to the hypothalamus, so cortisol continues to be secreted. This, in turn, causes more damage to the hippocampus, and even more cortisol production. Thus, a Catch-22 "degenerative cascade" begins, which can be very difficult to stop.
The hippocampus is part of the feedback mechanism that signals when to stop cortisol production, a damaged hippocampus causes cortisol levels to get out of control further compromising memory and cognitive function. The cycle of degeneration then continues.
Cortisol levels during human aging predict hippocampal atrophy and memory deficits. Chronically high cortisol levels, a problem that seems to be fairly common in older people. Magnetic Resonance Imaging (MRI) shows specific changes in the hippocampus were linked to changes in behavior associated with aging and Alzheimer's disease. Certain parts of the hippocampus shrink or deteriorate; specific, related memory abilities are affected. Furthermore, individuals with a shrunken hippocampus tend to progress more rapidly towards Alzheimer's.
The studies show that taxi drivers of metropolitans are renowned for their excellent memory in regard to spatial learning. It turns out they have enlarged hippocampi. Birds with a bigger hippocampus have a longer lasting memory for where they stored their food, compared to birds with a smaller hippocampus. British researchers provided evidence that "the enlargement of the hippocampus in food-storing birds may enable these birds to increase the duration of time over which they can remember spatial information."
One of the most basic behavioral differences between men and women is how they respond to stress. Men often react to stress with a "fight-or-flight" response, but women are more likely to manage their stress with a "tend-and-befriend" response. Females respond to stressful conditions by protecting and nurturing their young (the "tend" response), and by seeking social contact and support from others especially other females (the "befriend" response). This pattern is in sharp contrast to the fight-or-flight behavior, long considered the principal method both sexes used to cope with stress. Fight-or-flight means that, when confronted by stress, individuals either react with aggressive behavior such as verbal conflict and more drastic actions or withdraw or flee from the stressful situation. "Befriending" methods include talking on the phone with relatives or friends, to such simple social contacts as asking for directions when lost. The "tending" pattern is especially apparent in the differences between fathers' and mothers' behaviors with their children after a stressful workday. When the typical father in the study came home after a stressful day at work, he responded to stress by wanting to be left alone, enjoying peace and quiet away from the stress of the office; when office-related stress was particularly acute, a typical response would be to react harshly or create conflict with his wife or children. When the typical mother in came home from work bearing stress, she was more likely to cope with her bad day by focusing her attention on nurturing her children.
Men are more vulnerable to the adverse health effects of stress. Men are more likely than women to develop certain stress-related disorders, including hypertension, aggressive behavior, or abuse of alcohol or hard drugs. Befriend regulatory system may protect women against stress, this bio-behavioral pattern may provide insights into why women live an average of seven and a half years longer than men. The tend-and-befriend pattern exhibited by women probably evolved through natural selection. Thousands of generations ago, fleeing or fighting in stressful situations was not a good option for a female who was pregnant or taking care of offspring, and women who developed and maintained social alliances were better able to care for multiple offspring in stressful times.
Levels of stress hormones rise with aging, and are very likely to be responsible for the decline in neurogenesis. Extreme or sustained stress can damage the brain's hippocampus, making it difficult to learn new things. Stress can dramatically increase the ability of chemicals to pass through the blood-brain barrier, the complex system of blood vessels that protects the brain from toxins circulating in the bloodstream.
Solutions: An appropriate stress response is a healthy and necessary part of life. The best general approach for treating stress can be found in the elegant passage by Reinhold Niebuhr, "Grant me the courage to change the things I can change, the serenity to accept the things I can't change, and the wisdom to know the difference." There are a number of Ayurvedic treatments that are effective in relieving the symptoms of stress-related disorders:
Medications may include drugs to control anxiety and depression as well as drugs that treat such physical symptoms of stress as indigestion or high blood pressure.
Behavioral approaches are effective in helping people understand how they learned to overreact to stressors and in helping them reframe their perceptions and interpretations of stressful events. Relaxation techniques, anxiety reducing techniques and other physical exercise programs improve the body's relaxation response.
Pranayam, Yoga, Shirodhara, therapeutic massage, hydrotherapy, and bodywork are forms of treatment that are particularly helpful for people who tend to carry stress in their muscles and joints.
Aromatherapy, pet therapy, humor therapy, music therapy and share with friends other approaches that emphasize sensory pleasure are suggested for severely stressed people who lose their capacity to enjoy life; sensory-based therapies can counteract this tendency.
Naturopathic recommendations regarding diet, exercise, and adequate sleep and the holistic approach of naturopathic medicine can help persons with stress-related disorders to recognize and activate the body's own capacities for self-healing.
 

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