Distinctions
Normal aging (expected) vs. pathological aging (abnormal)
e.g., artherosclerosis - fatty deposits on artery walls which may start in childhood, but lifestyle may affect its course or severity; a comparison of individuals in Japan vs. the US finds lower blood pressure in Japan, potentially due to a less fatty diet; heart disease also occurs much later in life in Japan
Is the degree alterable or is it part of aging?
Primary aging (universal & inevitable) vs. secondary aging (from external damaging forces)
e.g., skin damage ? some wrinkles are expected, but sun exposure impacts the extent of the damage
Acute (short-term, infectious diseases, e.g., the flu) vs. chronic diseases (long term , progressive, & typically not curable, e.g., hypertension)
at least one chronic disease is found in 85% of adults 65+
among the very old, at least one chronic disease is likely to be present at autopsy; even if it wasn’t the immediate cause of death, it is likely to have caused death within months
therefore developing a chronic disease seems to be a normal part of aging
maximum life span vs. average life expectancy
maximum life span of humans seems to be around 105 - 120 years and this seems not to have increased; what has changed through the years is average life expectancy
BIOLOGICAL THEORIES OF AGING
Biological theories tend to focus on of two basic components of the human body:
1) cell aging (intracellular aging)
2) extracellular aging, e.g., the loss or stiffening of elasticity and collagen in our connective tissues
arteriosclerosis, narrowing of the arteries, is an example of the latter
Note: both artherosclerosis & arteriosclerosis are involved in the two most common causes of death with age - heart attack & stroke and seem to be relevant in other diseases of aging
Specific theories:
Random theories - no master plan, merely the passage of time and the build up of damage
DNA damage - increase in the number of mutations over the course of our lifespan - physical aging and death are outward signs of mutations in DNA; mutation leads to cell malfunction and eventually deathProgrammed aging theories - timer is set off that starts the aging processFree Radical damage ("rusting") - destruction of cellular elements via the build up of free radicals (cell waste products); antioxidants such as vitamins C & E have been found to prolong animals’ lives; likewise, in the nun study, those with higher antioxidant levels had lower disability rates
cell clock - it could be that within each cell there is a certain set life span; perhaps at a certain time - a protein may inhibit DNA synthesis causing cells to die offhypothalamus as a central clock ? the hypothalamus is responsible for many functions: eating, sexual behavior, temperature regulation, etc.; the hypothalamus as been implicated in menopause, shutting off estrogen production around the age of 50
immune system as a central clock - thymus, involved with immune response, slowly disappears during adulthood - may signal a weakening immune system that is less responsive to disease and less responsive to sparing our own cells; autoimmune responses may be implicated in diseases such as diabetes and dementia
EXTENDING THE MAXIMUM LIFESPAN
Discovering and controlling which one or which combination of theories affects aging may allow us to alter its course and extend our lifespans.
Two present life extension possibilities:
1) minimizing caloric intake: there is accumulating evidence that caloric restriction (undernutrition without malnutrition) can cause longer lifespans in mice
Many animal studies have indicated that restricting caloric intake in a nutrient rich diet (60 % of typical daily calories) can increase the maximum lifespan of these animals as much 60%!
2 caloric restriction strategies:
beginning at weaning --> delay puberty and thereby increase the period of time before adult fertility
after puberty --> more modest impact on life extension
some effects:
2) finding Shangri-La: Abkhazians from Georgia, Russia and the Vilcabambans from Ecuador were touted to be Shangri-Las where people lived to be over 100 regularly and who were active and healthy - a yogurt commercial in the 70’s showed the Russian group
In the first group, diet, exercise, and attitude were found to be important, In the second group there was evidence that people actually lied about their ages (using birth certificates of relatives for example), but still, the fastest increase in aging populations is in those over the age of 85 .
NORMAL AGING
two principles of normal aging:
1) variability of aging rates: there is great variation in individual aging rates, with variability being more dramatic with greater age. There is even variation within an individual.one common pattern: loss with disease2) variability of aging patterns: some abilities show steady decline; others are stable and may decline only at the terminal stages of life; still others improve.
Loss may occur only as a function of illness. From the Baltimore Aging Study, there was evidence that 1) in those who showed signs of heart disease, there was a loss of cardiovascular function over the years; those who were disease-free had no such decline; 2) testosterone levels in males decreased only in those older males who were ill; and 3) a decline in lymphocytes in some people actually predicted their death at the next testing, even though there were not outward signs of illness at testing.
loss in a stable function may signal impending death (physiological terminal drop)
another common pattern: compensation (e.g. with the brain, although there’s current research that shows that neurons continue to be made throughout our lives, there is still some loss of neurons; increases in dendrites and synapses makes for more efficient processing
There are biological losses with age; these tend to be gradual and begin, most likely, in our 20s. One reason that they may not be noticed until later is because our systems have what is called reserve capacity ? an excess capacity beyond what is needed in most normal, day-to-day situations.
In our youth, reserve capacity might be taxed in strenuous activities; in the old-old, even everyday activities may be impacted by the loss of reserve capacity. Changes in reserve capacity are apparent earliest to top athletes who are performing at levels beyond normal than to everyone else.
Hair & Skin
Most obvious signs of aging, begin to appear in one’s late 20s, early 30s
Gray hair - loss of pigment producing cells at the base of the follicle (each hair is actually white)
Also, change in the coarseness of the hair and the thickness of the hair
Wrinkles - cell production slows, epidermal turnover rate declines, loss of elastin and collagen which decreases the flexibility of the skin, reduction in dermal oil glands makes skin drier --- all exacerbated by sun exposure!!!
Also fat accumulates in certain areas (double chin, lumpy skin)
Other changes (less cosmetic): loss of blood vessels in the dermal area slows healing and increases susceptibility to heat and cold (sweat glands don’t work as efficiently)
Cardiovascular (CV) system
Heart weight increases w/ age (for women, this mainly occurs after menopause)
Heart walls, valves, blood vessels, in fact the whole CV system thicken (calcification) and narrow (stenosis) = arteriosclerosis
Accumulation of fatty materials on the walls of the arteries = artherosclerosis
Both impair circulation -> can affect both physical and mental ability
Extreme effects: myocardial infarction (heart attack) or cerebrovascular accident (stroke)
Risk factors: smoking high BP, high serum blood cholesterol, diabetes ? can be modified by diet and exercise
Gender: heart disease is the top killer for both men and women, but greater for men
Why?? Environmental factors (YES), but biological ones more so
Female hormone estrogen seems to have some protective effects with regard to heart disease
Ethnicity & Cardiovascular health
Japanese men have less artherosclerosis and less heart disease than US males, also seen with Chinese and Japanese men in Hawaii ? longest life expectancy for males at 78 years
African-Americans are at high risk for heart disease ? greatest threat is stroke
High BP ? also likely to develop earlier and, thus, it may go untreated for longer
Diabetes ? also occurs earlier and is prevalent in A-A women
Heart Disease Interventions
Multiple Risk Factor Intervention Trial (1982) - intervention study on 12,866 men from 35 ? 57 with high blood pressure, and a history of smoking and high-fat diets ? 7-year follow-up showed lower blood pressure and cholesterol levels in the intervention group (group and individual counseling), but similar mortality rates in those who had and had not been through the intervention
Recurrent Coronary Prevention Project - a study of 1000 type A men who had already experienced a heart attack, showed that type A behavior was reduced by behavioral modification focused on time, urgency, and hostility. Furthermore, there was a 45% lower rate of recurrent cardiac events (fatal and nonfatal MIs) in the behavior-modification group over the 3 years of the intervention, compared with those who had not received training in behavior modification.
THE NERVOUS SYSTEM
two systems: the central nervous system (the brain and spinal cord) and the peripheral nervous system (the neurons branching out from the spinal cord)
in both systems, the basic building block is the neuron
In our 30s, the brain begins its gradual decrease in size and weight: the sulci widen, the cerebral folds narrow, the ventricles increase in size; some of this change is due to the loss of glial cells, but most from changes in the neurons
neural loss occurs in both the number of cells and in the size of cells, but there is plasticity (the ability of the brain/neurons to make new connections) ? dendritic growth occurs throughout our lifetimes
the concept of variability applies in this area, too:
at 68, only about 50% may show atrophy (loss and shrinkage of neurons, larger ventricles, appearance of plaques and tangles in areas like the hippocampus and the neocortex)
Example of Sister Mary ? she had only an 8th grade education, but started teaching 7th and 8th grade when she was 19, earned her high school degree at age 41 by attending summer classes for 22 years, retired at age 81, and at 98, she decided to join the nun study. She was tested at age 101 on the Mini-Mental State Exam, earning a score of 27 (24 - 30 is good for a high functioning older adult); her predicted score based on her age and education would be about 4! At her death, her brain was donated to science. Even though it showed numerous lesions associated with AD, the location of her damage was more in the hippocampus rather than the neocortex (where AD is found to be worse)!!
LIFESTYLE, AGING, AND DISEASE
health practices associated with better living include:
physical activity, not smoking, maintaining normal weight, not drinking to excess, sleeping 8 hours per night, eating breakfast, not eating lots of snacks, and drank moderate amounts of alcohol
social isolation and longevity ? factors that are highly correlated with longevity include marital status, contacts with friends and relatives, and church attendance.
reminder ? these correlational results based on a predominantly white, middle class samples , but other, experimental research more clearly indicates the benefits of diet and especially exercise on longevity
Stress & Coping
Stress is also associated with less-healthful aging
Holmes and Rahe (1967) proposed that the number and severity of stressful events that one was exposed had a negative influence on health. They came up with their life events stress scale and found that those who had experienced major life changes in the past 6 months were more likely to have developed an illness. This seems consistent with our general view of how stress works.
How might this occur? Hans Selye's General Adaptation Syndrome (GAS):
an example: Type A behavior
For awhile, it was thought that Type A behavior (workaholic, competitive, hostile) was associated with an increased risk of heart attacks, more recent research indicates that it is the hostility aspect that is the important predictor and only predicts heart attacks in middle age adults - the hostility is related to a type of coping style that often blames or is suspicious of others
Negative explanatory style has also been linked to an earlier death by Seligman and his colleagues. He finds that those who are optimistic do much better.
Control may also be important. In a famous study by Rodin and Langer (1977) nursing home residents were randomly assigned to a decision-making group (planning meals and visits, taking care of a plant) or to a we'll-take-care-of-you group. Those with more control over their situations were likely to live longer (15% died vs. 25% in the no-control group over an 18-month period).
Bandura further suggest that those with higher levels of self-efficacy may be more likely to follow recommendations for altering one’s lifestyle
some other factors related stress and our reactions to it (from Chapter 8):
the timing of events - stressful events that happen on-time or when they should (normative) are coped with better than when those events that happen off-time (non-normative)
problem-focused coping and emotion-focused coping: older adults are slightly more likely to use emotion-focused coping (taking responsibility, distancing, positive reappraisals) than problem-focused coping (actively working to change a situation)
some mature coping styles: altruism, humor, suppression (looking for a silver lining), anticipation (preparation), sublimation
positive reappraisals: e.g., deriving a sense of personal meaning, an attempt to gain mastery (e.g., changing diet or lifestyle), and social comparison
denial, often thought of as a negative coping response, may actually be healthy in some situations - may be useful for a short time until one can muster up the resources to cope emotionally with highly stressful situations (e.g., being diagnosed with a severe disease)