A person born in 1776 could expect to live 35 years. By the year 1900, the average life span was 47 years. But a baby girl born today can expect to live 79 years, and a baby boy, 72 years.
The most dramatic increases have been in the number of people who are living 100 years or more. Today, there are 50,000 centenarians in the United States, but there are projected to be one million by the year 2050.
Jason Wilbur, MD, Medical director, UI Family Care Center – Family Medicine Clinic at University of Iowa Hospitals and Clinics, talks about healthy aging:
Why do we age?
The fact that we're having this discussion about age is a lucky byproduct of the times in which we live. We're living longer than people would have a few hundred years ago when we wouldn't be able to even discuss or be interested in aging. We don't have to run away from sabre tooth tigers and we aren't dying from simple infections. Aging is a topic that's of interest now, and may not have been a hundred years ago.
Aging is really a mystery. It's poorly understood. Only recently had it become something that's not fringe-science to study. We're beginning to understand more about aging—why and how we age. We do know a few things about aging. We know that aging is a process that occurs over a fairly long period of time in humans, and shorter periods of time in other animals, but that seems to occur in almost every complex organism. Aging results from diminished physiologic reserve, the capacity to heal and avoid disability from illness and injury. That physiologic reserve is what allows three year olds to fall down multiple times and get up again and not be hurt. But when you're 80, you fall down and may break a hip.
Also, aging is a principal risk factor for most diseases seen in adults. If you think about Alzheimer's disease, or cardiovascular disease, or cancer, aging would be the main risk factor for any of those.
We do know that aging is dependent on genetic factors to some degree but that it's kind of complex and it hasn't really been completely ferreted out. Exactly what human genes affect aging are not really known right now. There are also environmental factors that seem to be associated with the aging process. An example here would be ultraviolet light exposure. People who are exposed to ultraviolet light for longer periods of time tend to have more rapidly expressed aging of their skin. They have more skin cancers and more wrinkles and this sort of thing. One of the most commonly held theories of aging now says that natural selection tends to favor aging, so there may be evolutionary pressure to our growing old and a lot of that would have to do with these genes that I mentioned before that haven't been identified.
Is there one reason or many reasons why the average lifespan has increased over the years?
I will say the average lifespan has increased for a lot of reasons. I don't think it is one thing—in particular the extinction of sabre tooth tigers. We do like to think of our highly technologically sophisticated medical system as playing an important role in us living longer. But that's probably a small contribution to our overall longevity when you look at the population.
For our population as a whole, it's much more important that we've had significant improvements in:
- Sanitation
- Infection control
- Nutrition
- Occupational safety
We've reduced the threat of many previously deadly childhood diseases, like polio and smallpox, through mass immunization. There's also the fact that effective antibiotics have only been around for 60 or 70 years and that has allowed many simple infections to be eradicated or treated more easily, when previously they could have resulted in death or serious disease.
How large a role does genetics play in aging? If our parents live to be in their 80s, is there a better chance we will too?
Probably a lot is accounted for by genetics, but it doesn't appear to be a single gene that carries longevity. We have a hard time saying that if your mother lived to be 90, you have a certain percentage chance of living to be that old. I can say I'm aware of families who seem to have some increased longevity. My in-laws seem to have lived a very long time and they have a lot of older adults in their family living into their 90s. When we look at studies of populations, they don't seem to support a link between an individual's lifespan and ancestral longevity. In other words, there's not an equation we can use to account for ancestral longevity in a person's lifespan. It's not too simple. It's probably more complicated and needs further study.
Can we slow the aging process physically? Mentally? How?
I would say that aging begins at 30. A lot of how we age begins then or probably even earlier. We talk about successful aging, which is living longer with less disease and disability. Successful aging is really affected by what we do early in life. Later in life it becomes harder to make lifestyle changes that can significantly impact our longevity.
One example is that osteoporosis is really a disease seen predominantly in older women, but the disease process is laid in an early age That foundation of bone strength is laid in our early teen years and as an early adult we've pretty much made up our bone strength. Even though osteoporosis is a disease of older women, it really has its roots in how much calcium and vitamin D and exercise adolescent girls get.
There are some good studies that show us that successful aging correlates well with higher education, so people who are more educated tend to have a little bit longer lifespan and have less disability. Greater amounts of exercise are strongly correlated with successful aging. And healthy diets seem to have some effect, too. And all of these things seem to be more important than ancestral longevity that we talked about earlier.
Is it possible to extend your lifespan and become healthier in later years by changing behavior (diet/exercise) and seeking certain types of care (medical testing)? Explain.
My best answer is we don't really know. We can give you some examples. I could say that patients who have been diagnosed with lung cancer and who smoke will do better if they stop smoking. They'll have a longer life than if they continue smoking. So even at that late stage in the game, you can make a difference by a lifestyle modification. We do know that older people can improve endurance and muscle strength with exercise. We know that diabetes can be controlled through diet. So you would suspect that a lot of these things would have an effect on overall longevity, even kind of late in the game, when patients are aging and have more difficulty with disease.
I think it's important for healthy, older adults to engage in preventive medicine:
- Colon cancer screening that can be done many ways
- Breast cancer screening with mammograms
- Prostate cancer screening that can be done a couple different ways
- Immunizations later in life reduce disability and keep people functional and healthy
Whether or not I can say any of these things increase our lifespan—I don't know. I do know that there are some examples that lead you to believe this. I do want to comment on the fact that our society is really interested in aging—reducing our disability and improving our function, and that's very appropriate. However, if you're out there surfing the Web and looking for ways to extend life, there seem to be some unfounded arguments out there for selling people things for life extension. I think patients who are interested in extending life or improving function in later life, need to be careful and discuss (maybe if they're thinking about taking herbal medications or engaging in a certain program), that with their physician.
It sounds like most people would like to add life to their years rather than simply adding years to their life. What is your best advice for people as they age?
I would keep it simple. Staying physically active is very important, and that includes regular exercise as well as getting out and moving around. It doesn't have to be anything as dramatic as running a marathon, although I've known older patients who do those sorts of things. It's very important to remain socially engaged. Some older patients of mine have lost friends and family members and become kind of isolated. That isn't good for our mental health—our cognitive health—or our physical health. So staying socially engaged is important. Eating healthily is also important, and it's not something to give up in later years. Quitting smoking at any age has its benefits along with moderate amounts of alcohol—which for older patients is probably no more than one drink a day.
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