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Nobody enjoys growing older (though it certainly beats the alternative).
As we age, our bodies change in a multitude of different ways. Along with graying hair and wrinkles, there is also a general decline in physical stamina due to decreased bone mass, decreased metabolic rate, and reduced functioning in all our organs. Aging also means more memory and concentration difficulties, increased reaction time, declining sexual activity, and greater vulnerability to emotional problems such as depression. Compared to how we were at age 30, a 75-year-old human will only have 70 percent heart capacity, 40 percent physical stamina, and 38 percent of the taste buds. Hearing, vision, touch, smell, and taste are all affected as well.
Whlle aging is an inevitable part of life, there are still things we can do to slow down the aging process, or at least to ensure that we can remain as mentally and physically fit as we possibly can over time. Lifestyle changes can play an increasingly strong role in buffering many of the physiological changes linked to aging.
A new article published in the journal Geropsych provides a comprehensive overview of the latest research examing why we age and what we can do to promote healthy aging. Written by Thorsten Kolling and Monika Kopf of the Johann Wolfgang Goethe-Universität Frankfurt am Main in Germany, the article reviews some of the basic theories about why we age and how lifestyle factors and changes to the environment can influence aging.
According to Kolling and Kopf, the various theories that have been put forward to explain why we age can be grouped into three categories:
- Evolutionary aging theories - Since natural selection is linked to reproduction, our bodies are most fit during the first half of our lifespans when we are most likely to have children. As we grow older and reproduction has probably already taken place, the negative effect of our genes becomes more apparent since there is no evolutionary benefit in prolonging our lifespans. As the human lifespan increases due to advances in medicine and better health care, we are seeing more age-related health problems because the "evolutionary architecture" for the last part of our lives is lacking.
- Stochastic aging theories - As we grow older, the process of living causes us to accumulate "wear and tear" leading to tissue and organ death and, eventually, the complete breakdown of our bodies. Linked to this is the theory that the chromosomes in our body accumulate coding errors caused by cellular mutation. Some researchers have also suggested that "free radicals" or chemically reactive atoms or molecules produced by oxidation can produce damage that builds up in our cells over time. Treatment with antioxidants has been used to try reversing the effects of aging but the results are still controversial.
- Deterministic aging theories - Some researchers suggest that we are genetically "programmed" to live a natural lifespan and that this programming is based on internal "markers" that determine how long we live. One of the oldest deterministic theories suggested that our lifespans are linked to the number of heartbeats or calories consumed. Supporters of this theory often compare animals with different metabolic rates and how this is linked to lifespan. Even when body size is taken into consideration, animals with faster heart rates or metabolisms have shorter lifespans than humans. Another deterministic theory suggests that we have a genetic "clock" that controls the age at which different life stages happen. Since there is a limit to how many times the cells in our bodies can regenerate, our bodies wear out.
Though no one theory can explain the aging process completely, recent research findings have shown support for the concept of a genetic "clock" in the cells of our body. Telomeres are essentially disposable "buffers" on the end of chromosomes that help stabilize and protect them from deterioration. Each time a chromosome replicates, the telomere ends become shorter and less effective at stabilizing chromosome functioning. In humans, chromosomes can only replicate forty to sixty times before cell death occurs reflecting our relatively long lifespans. In mice, for example, chromosomes can only replicate fourteen to twenty-eight times. In Galapagos turtles (which can live for well over a hundred years on average), chromosomes can replicate 90 to 125 times.
While the link between telomere length and mortality is still controversial, research shows that telomere length can be a risk factor in a number of age-related diseases such as Type 2 diabetes, heart disease, and dementia. Children with progeria (a premature aging disease) have telomeres that are much shorter than average and the number of times their chromosomes replicate is well below average for humans. Longer telomeres are also associated with better performance on tests of memory, attention span, and problem-solving.
But how can our lifestyles influence the aging process? To answer that question, Kolling and Kopf reviewed research looking at how telomere length was linked to positive lifestyle factors such as exercise and meditation as well as negative lifestyle factors such as alcoholism, obesity, and smoking. As one example, it has been long known that chronic alcohol abuse can lead to premature aging because of cell damage, an impaired immune system, and overall damage to the body's different organs. In recent years though, researchers have also found that alcohol abuse is linked to reduced telomere length. Even when other factors such as smoking, age, and job stress were taken into account, the alcohol/telomere length link is extremely strong.
Other lifestyle factors linked to shortened telomere length include smoking and obesity, both of which appear to accelerate human aging. According to one study, smoking a pack a day for forty years can correspond to four to seven years of extra aging. Stress and depression have also been linked to shortened telomere length. In people with serious mood disorders, this can amount to as much as ten years of accelerated aging.
As for positive factors that can lead to longer telomeres, dieting and exercise appear to be extremely effective. While morbid obesity can cause shortened telomere lengths, a new research study has also found that significant weight loss can lead to longer telomere lengths. A 2008 study involving a mixed-age group of twins found that increased physical activity in leisure time was associated with longer telomere length even when Body Mass Index, smoking, age, sex, and socioeconomic status were taken into consideration. On the other hand, a sedentary lifestyle appears to have the opposite effect, even on young people. Meditation and other stress management techniques also appear to result in longer telomeres though these results are still controversial since few studies have been done so far. As for life context factors such as socioeconomic factors, the existing evidence seems mixed at best.
So, what does all this mean for older people hoping to live longer? While aging is inevitable, Kolling and Kopf point out that the lifestyle choices we make can play a huge role in staying healthy and active in old age. Negative lifestyle choices (such as drinking, smoking, lack of exercise, and stress) definitely accelerate aging while positive lifestyle factors (including healthy eating, exercise, and meditation) can have the opposite effect.
Though more research is needed to disentangle how biological and psychological factors work together in producing the changes linked to aging, the challenges posed by growing older is something that everyone must face. Being able to handle the physical ailments that come with age and making the most of our remaining abilities requires strength, acceptance, and a touch of humor.
In the immortal words of actress Bette Davis, "Old age ain't no place for sissies."
