Wear and Tear of Stress: The Psychoneurobiology of Aging

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Wear and Tear of Stress: The Psychoneurobiology of Aging

 

American Psychological Association

 

" Age may be more related to reactions to stress and the absence of disease

rather than to a person's chronological age. "

 

Age may be more related to reactions to stress and the absence of disease rather

than to a person's chronological age, say leading researchers in the fields of

neurobiology and psychoneuroendocrinology. And healthy aging is a good bet if

stress can be moderated along with adopting an active, healthy lifestyle. This

finding will be presented at the 114th Annual Convention of the American

Psychological Association (APA).

 

From a review of studies on how stress hormones affect the brain, psychologist

Bruce McEwen, PhD, of the Laboratory of Neuroendocrinology at The Rockefeller

University, finds more evidence that biological and behavioral stress responses

can be adaptive in the aftermath of stress, but can also cause damage when they

are over- or under-produced and go on for a long time. " Acute stress seems to

enhance immune function and improves memory but chronic stress has the opposite

effect and can lead to disorders like depression, diabetes and cognitive

impairment in aging, " said Dr. McEwen.

 

Cumulative stress effects, said McEwen, are showing up in people who are under

constant stress, like those in caregiver situations or those who suffer from

obesity and/or diabetes. These people are more likely to have decreased

telomerase activity. Telomeres are enzymes that regulate how many times an

individual cell can divide. Telomeric sequences shorten each time the DNA

replicates, which is a process that happens prior to cells dividing. When at

least some of the telomeres reach a critically short length, the cell stops

dividing and ages (senesces) which may cause or contribute to some age-related

diseases.

 

There is also more evidence that the brain is more involved in a person's stress

response than previously thought, said McEwen. The brain interprets what is

threatening, i.e., what is stressful (whether it be public speaking or

perceptions of social status) and then regulates the behavioral and

physiological responses through the autonomic, immune and neuroendocrine

systems. If the brain is under too much stress for too long, said McEwen, " we

can see structural and functional remodeling changes that affect how it

functions. "

 

" These brain changes, which appear to be reversible, are able to change by not

only pharmaceutical agents but also by lifestyle changes like exercise, diet and

social support, " said McEwen.

 

In another review of the current literature on the interactions of the brain,

stress and the endocrine system, more evidence shows how cumulative stress and

the occurrence of disease may define age more than chronological aging.

According to the review, certain diseases start to occur when the anabolic

hormone levels start to decrease - when the tissue builders like growth

hormones, testosterone, estrogen and thyroid functions start to drop off and

when the catabolic hormones start to increase. These hormones, the tissue

fuelers, can become too active and actually break the body down. Cortisol - a

stress hormone - can become more reactive when responding to acute challenges as

one gets older.

 

This imbalance between the anabolic and catabolic hormones is likely to be

responsible for many of the psychiatric and medical diseases associated with

aging, said researcher Elissa S. Epel, PhD, of the University of California, San

Francisco. According to a model of neuroendocrine aging, " subtle yet chronic

changes in hormonal patterns can exert pathological effects on health over

time. "

 

It is also known, said Epel, that chronically elevated cortisol reduces lean

mass, bone density and shifts fat distributions that can precede the onset of

many age-related diseases like osteoporosis, metabolic syndrome, Alzheimer's

disease and major depression. But, she added, certain behavioral factors, like

lifestyle and exercise can modify some of these hormonal effects that seem to

accelerate aging.

 

Compared to healthy older adults under 100 years of age, healthy centenarians,

said Epel, tend to show slower insulin and glucose rates when fasting, have

higher or similar thyroid hormones and have similar cortisol and growth hormone

levels. Even though older adults are exposed to more chronic stressors (more

health problems, fewer social connections), they do not necessarily experience

greater daily stress. The authors believe that the healthy centenarians are

using coping techniques such as finding meaning in activities and strengthening

meaningful social ties to help moderate chronic stress.

 

Centenarians also report using three coping strategies to deal with their health

problems: acceptance, not worrying and taking things one day at a time. Those

older adults who do not employ these types of strategies, said Epel, may become

more vulnerable to stress over time.

 

Many of the neuroendocrine changes that occur with aging are not inevitable,

said Epel, and " this is demonstrated by healthy centenarians. Certain

age-related changes can be modified with physical activity, sufficient sleep and

good coping techniques. It is when chronic stress, inactivity and added body

weight take hold that the neuroendocrine system becomes off balance. This

imbalance between the anabolic and catabolic hormones now appears to be the most

common profile of aging and may be a valuable marker for biological aging. "

 

 

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