Resilience, Stress, and the Neurobiology of Aging
Resilience, Stress, and the Neurobiology of Aging
The aging of the world’s populations represents one of the most remarkable success stories in medicine and of humankind, but it is also a source of various challenges. Getting older can be stressful because of multiple losses (eg, interpersonal, financial) and a decline in health, independence, and cognitive and functional abilities.
Worldwide, human life expectancy has increased steadily for nearly 200 years and this trend is expected to continue. In every decade of the past century, life expectancy increased by about 2 years. This increase was driven in the first decades by improvements in sanitation, housing, and education. A steady decline in early and midlife mortality was mostly the result of our ability to prevent and treat infections. The increase in life expectancy in the latter half of the century was almost entirely attributable to a decline in late-life mortality secondary to medical advances and improved socioeconomic conditions.1
Many older adults are living longer with chronic illnesses yet are making the best of their later years. As George E. Vaillant2 pointed out in his book Aging Well, “The major factors involved in negative personality change at midlife are the same factors that caused negative aging at 70: bad habits, bad marriage, maladaptive defenses, and disease.”
The benefits of a positive outlook
Empirical evidence now supports the long-held belief that positive emotions are good for one’s health. Fredrickson’s “broaden-and-build theory” shows how positive emotions contribute to psychological and physical well-being through more effective coping.3,4 It is a natural drive to seek personal happiness and fulfillment regardless of age. Successful aging is associated with a positive psychological outlook in later years, general well-being, and happiness.2,5-7
With global trends in population aging, many nations are developing and implementing healthy aging policies to promote quality of life and additional years of health.7 One direction is to improve resilience to stress.
Depp and Jeste6 have defined resilience as “the ability to maintain biological and psychological homeostasis under stress. It may vary with context, time, age, gender, and cultural origin. Inquiry into resilience has evolved from descriptions of resilient qualities to uncovering the process of resilient adaptation. In older adults, resilience has been studied mostly in the context of successful aging (eg, in centenarians) or in the context of recovery from injury or illness.” The question remains whether resilience can be operationalized and taught to older stressed individuals and whether any interventions exist that boost resilience to stress and life’s adversities.
CHECKPOINTS
? Human responsiveness to stress may be attenuated by learned or adaptive skills, retraining, or increased resilience to future stress.
? Physiological mediators such as adrenaline from the adrenal medulla, glucocorticoids from the adrenal cortex, and cytokines from the cells of the immune system act on receptors in various tissues and organs to produce effects that are adaptive to stress in the short run but can be damaging if the mediators are not shut off when no longer needed.
? Prospective determinants of resilience for future studies include neuroendocrine, immunological, neural, genetic, temperamental, and environmental influences.
Stress and aging
Selye8 coined the term “stress” to define the alarm reaction, the stage of resistance, and the stage of exhaustion in animals and in humans. Only when the subject is overwhelmed or derailed does the stress response system begin to cause disease.9 Exposure to stress can be characterized in several ways: duration (acute, chronic), responsiveness (adaptive, hyperadaptive, nonresponsive), and severity (mild, moderate, extreme).10
Human responsiveness to stress may be attenuated by learned or adaptive skills, retraining, or indifference to future stress. The hypothalamic-pituitary-adrenal axis can be up regulated by a stressful experience, with increased amounts of circulating glucocorticoids, catecholamines, serotonin, and cytokines. These acute responses can lead to pathological changes that may be amplified by the aging of the brain.10
The adaptive physiological response to acute stress that involves internal milieu adjustment to change in the environment was initially described by Sterling and Eyer.11 McEwen12 extended this definition to include the concept of a set point that changes because of the process of maintaining homeostasis in the body that is mediated by the neuroendocrine, autonomic nervous, and immune systems. Allostasis is the term used to describe this process of “maintaining stability through change.”
Physiological mediators such as adrenaline from the adrenal medulla, glucocorticoids from the adrenal cortex, and cytokines from the cells of the immune system act on receptors in various tissues and organs to produce effects that are adaptive in the short run. If the mediators are not shut off when no longer needed, they can lead to deleterious effects of chronic stress, including receptor desensitization and tissue damage.
Aging can contribute to poor responsivity to stress because of reduced resilience.13 Accumulation of wear and tear caused by daily experiences and major life stressors can interact with genetic constitution and predisposing early life experiences to produce individual differences in the age-related diseases.10,13,14
Unfortunately, one never sees in any discussions about stress, any mention of anxiety disorder, which affects, in varying degrees, 20-25% of Western people (it is unknown in traditional societies, like the Kaluli in Papua, or in Japanese fishing villages). This widespread misunderstanding may be due to the mistaken popular notion that anxiety and stress are the same thing, and are both caused by traffic jams and other purely external stressors. The proper description of the effect of external stress would be internal strain, which lasts for only minutes or hours, unlike true anxiety, which is lifelong. Anxiety disorder arises during foetal development, and is the result of a fatty maternal diet--that often causes gestational diabetes as well--the direct cause being a leakage of maternal cortisol across a mildly inflamed placenta. This hormone changes the foetal brain permanently, by epigenetically modifying the glucocorticoid receptor gene promoter, thereby reducing negative feedback from adrenal cortisol, which promotes increased CRF and HPA axis overactivity. Anxious folk lack resilience, and also comfort-eat fatty foods, which leads to obesity, diabetes, depression, vascular disease, arthritis, osteoporosis and muscle wasting. Fatty diet causes both insulin resistance and systemic oxidation, and the latter drives cytokine production and low-grade inflammation, and also drives telomere shortening. Low-fat diet turns depression back to anxiety in 2 weeks. To convert anxiety to resilience takes about 7 days: just give the subject 5 gm of Inositol supplement daily: this simple seed sugar allays anxiety by inhibiting serotonin 2A receptors, which blocks CRF action. Within 3 days there is unusual energy, and a shift of appetite from sweet fatty foods to salads and fruit. By the seventh day, there is newfound calmness and mental clarity, followed within weeks by fat loss, larger muscles, a liking for exercise, better libido, and better immunity. Hair and nails grow faster, and appear shinier and stronger. Inositol is ALSO anti-ageing--it is found abundantly in the legumes and whole grains (like oat porridge) eaten by most healthy centenarians (tip: citrus is a good source), and is known to activate 100s of anti-ageing genes (J Barger, 2008). Its IP5 metabolite inhibits the key nutrient-sensing enzyme PI3 Kinase, fooling the cell into thinking that the subject is on Caloric Restriction. Inositol is also directly involved in telomere maintenance (see "inositol and telomere" on PubMed). Remember, diet MUST be low fat, for best effect.
An excellent article re stress in the aging population.The emphasis placed on youth in our culture only exacerbates the problem.Can you imagine Zsa Zsa Gabor with only one leg??or even the youth who actually can't even imagine themselves as "old"?Resilience and an inner life is the key-thanks for the great article-JL.
Normal 0 0 1 250 1429 11 2 1754 11.1287 0 0 0 Wise advice! This post highlights the importance of stress management for children, teens and adults. Families and school staff concerned about a student with such problems can turn to this link from the American Academy of Child and Adolescent Psychiatry listing free helpful pamphlets for most common emotional conditions affecting youth and families: http://www.aacap.org/cs/root/facts_for_families/facts_for_families These pamphlets are available in English, Español, Malaysian, Polish, Icelandic, Arabic, Urdu and Hebrew. (Links are on the aacap site listed above.) Another source of insight is the Stressed Family, Strong Family website, at this link: http://americanconfusion.com where you will find many ideas from the e-book, Stressed Family, Strong Family. Many can learn to cope with stress more effectively, and support one another.