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Researchers Examine Impact of Exercise on Aging

March 31, 2008 at 6:35 PM EST
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Scientists have coined a new term -- geroscience -- to describe research that aims to slow down aging and delay the onset of age-related diseases like Alzheimer's and Parkinson's. Researchers are studying the underlying genetic causes of aging and effects of exercise.
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GWEN IFILL: Now, living longer, living better. NewsHour correspondent Spencer Michels has our Science Unit report.

SPENCER MICHELS, NewsHour Correspondent: The watchword at The Redwoods, a retirement community north of San Francisco, is “keep active.” Line dance, even if you’re using a walker, stay involved.

The subtext, of course, is that, if you exercise your body and your mind, you will be healthier and may live longer.

And, in fact, the number of older persons has tripled in the last 50 years. And in the U.S., life expectancy has gone up to almost 78 years. Now scientists are starting to believe they can extend that dramatically and at the same time attack diseases of the elderly.

Some of the clues to longer life are coming from tiny roundworms or nematodes, which normally live just a few weeks, making them good subjects to study.

For a decade, researchers like Gordon Lithgow have been working with these transparent, almost microscopic worms, often by manipulating their genes.

GORDON LITHGOW, Buck Institute for Age Research: We can increase the lifespan 100 percent, 500 percent. There’s even some occurrence of 1,000 percent increases in lifespan.

But the big news is that a lot of these genes are similar to human genes that are involved in disease and specifically age-related disease. And that’s where a lot of the excitement is coming from.

SPENCER MICHELS: Lithgow and other age researchers contend that understanding and slowing down the aging process, a goal in itself, may also hold the key to delaying the onset of many diseases that occur in old age.

Lithgow works at the Buck Institute of Aging, an independent research center in the hills north of San Francisco, where Dale Bredesen is a researcher and the CEO.

DALE BREDESEN, CEO, Buck Institute for Age Research: When you have an animal and you make a genetic manipulation that allows the animal to live longer, it puts off all of the associated diseases. That argues that, if we’re out there looking for treatments for Alzheimer’s and treatments for cancer, et cetera, maybe these are all one treatment. Maybe these are all something we should be focusing, not on each disease by itself, but on the aging process itself.

Geroscience

Thais Crowell
94 Years Old
I have always exercised somehow or another. Here I go four times a week to just regular exercise, and then I do tai chi, which I love. I do the line dancing once a week.

SPENCER MICHELS: Lithgow has coined a new term for the interdisciplinary work he and his colleagues are doing: geroscience.

GORDON LITHGOW: We have people interested in individual human diseases like Alzheimer's and Parkinson's. And we've realized that we're all kind of working on the same thing, really, and the same genes and the same mechanisms are at play. We started to use this word "geroscience" as an umbrella term.

SPENCER MICHELS: The National Institutes of Health recently awarded the Buck Institute $25 million to study geroscience using an interdisciplinary approach. That's a large grant for a small research facility and part of the NIH's push to encourage experts in several fields to come together to attack complex scientific problems like aging.

At the Buck's 15 different labs, scientists studying a range of diseases regularly share their findings with one another. Here, yeast, a single-cell organism, is used as a screening mechanism for potential drugs that might impact Huntington's, among other diseases.

These worms are bred to be fluorescent so their neurons are visible which is helpful when studying Parkinson's.

These fruit flies are being used to study the impact of dietary restrictions on the aging process. Scientists have found that cutting down calories extends the life of some animals.

And mice are used here to study the damaging effects of chemicals that attack molecules crucial for cell function, something that will help Buck researchers like Simon Melov better understand the aging process.

SIMON MELOV, Buck Institute for Age Research: We need to take those findings in those model systems and translate that into human beings.

SPENCER MICHELS: And Melov has done just that. He, along with a researcher in Canada, studied the same cell processes in humans that he had been studying in mice.

PERSONAL TRAINER: Getting tired yet? Sweating? Good. Push it.

SPENCER MICHELS: These seniors participate in a strength training class at The Redwoods. Melov investigated exercise like this as a way to rejuvenate muscle tissue and slow down or even reverse biomarkers, biological indicators of aging. He found that exercise actually reversed the aging process.

SIMON MELOV: We were able to very clearly show that these biomarkers of aging were reversed to a very large extent back to that of younger individuals just through resistance training over a period of six months. Now, we know from other studies that if you stop exercising, it just goes back.

SPENCER MICHELS: These active retirees know from their own lives that exercise keeps them feeling young. Ninety-four-year-old Redwoods resident Thais Crowell, whose parents both died in their early 60s, is a case in point.

THAIS CROWELL, 94 Years Old: I have always exercised somehow or another. Here I go four times a week to just regular exercise, and then I do tai chi, which I love. I do the line dancing once a week.

Looking to genetics

Cynthia Kenyon
University of California-San Francisco
The reason that so many different labs are studying these processes is that it's a big process. It's not just one gene and one thing.

SPENCER MICHELS: Figuring out why some people or animals live long and why others don't has become a major scientific goal at many institutions.

Like the Buck, the much bigger University of California-San Francisco also got an NIH grant to foster interdisciplinary studies of aging. The model for those studies is different. Researchers at UCSF are spread throughout two large campuses, but the goal of working together is the same.

CYNTHIA KENYON, University of California-San Francisco: Any time something comes up in my lab, I have 10 people here I can call and I can say, "Let me ask you a question about this."

SPENCER MICHELS: Cynthia Kenyon, who heads USF's Center for the Study of Aging, is also doing research on transparent worms. Here, her lab is focusing on extending life by killing part of a specific worm cell.

CYNTHIA KENYON: She is going to kill this cell with a laser, so she hit it right there. You can see -- yes, it's starting to look different. So she's killing it. So these are cells that we know control lifespan. So when she kills the cell, the worm will live longer.

SPENCER MICHELS: Kenyon says that while gene manipulation in worms and fruit flies, mice and even dogs has been going on for two decades, it remains complicated.

CYNTHIA KENYON: The reason that so many different labs are studying these processes is that it's a big process. It's not just one gene and one thing. It looks as though aging is caused, at least partly by processes that damage the tissue.

The reason that these animals can stay young longer is that they're better able to protect themselves against damage and they're better able to repair the damage once it's taken place.

SPENCER MICHELS: What Kenyon and other researchers are aiming at is not just extending life, but extending youth and health, so that the diseases of old age will be postponed.

CYNTHIA KENYON: If you're 80, but you're really like a 45-year-old, if you look like a 45-year-old, I mean, you're not just healthy, but you are young, then you're not going to be susceptible to these diseases until much later.

SPENCER MICHELS: Several companies, including one she founded, are trying to make a pill that would slow down the process that makes people age. It would mimic gene manipulation.

CYNTHIA KENYON: And then all these diseases of aging are postponed by this pill. So how realistic is this? We already know that this can happen in these long-lived animals. We see it. It's amazing.

'A pill to cure aging'

Simon Melov
Buck Institute for Age Research
It's sort of not productive to talk about developing a pill to cure aging. Certainly, we will be in a position to help alleviate some of the symptoms of aging and maybe even reverse specific aspects of the aging process.

SPENCER MICHELS: But that approach is controversial and premature, says the Buck's Simon Melov.

SIMON MELOV: It's sort of not productive to talk about developing a pill to cure aging. Certainly, we will be in a position to help alleviate some of the symptoms of aging and maybe even reverse specific aspects of the aging process. But talking about, you know, living for 500 years, 1,000 years, is a little bit kind of flight of fancy, frankly.

SPENCER MICHELS: The residents of The Redwoods are intrigued by the prospects of living longer and healthier. They do their own part by being as active and engaged as possible. But the idea of a pill to extend life? A mixed reaction.

JOSEPH LEVINE, 74 Years Old: We volunteer. Bring the pill. But I would differ to a certain extent. You have to have a reason to get out of bed in the morning.

FREIDA ENGLE, 90 Years Old: I would be interested in every research experience, every research piece that talks about the quality of life and how that can be extended.

KATHLEEN BURGY, 92 Years Old: I'm much more focused on how I'm living day by day now. And I'm very grateful, at the age of 92, to still feel comfortable and content and engaged.

SPENCER MICHELS: Researchers warn that studying aging in humans is very difficult and expensive since people live a long time compared to most animals that have been studied. But Cynthia Kenyon, whose company could profit, is optimistic that big breakthroughs are near.

CYNTHIA KENYON: This is a revolution. This is a big deal. It's like going to the moon. It's like Ponce de Leon, you know? It's like the quest for the Fountain of Youth when there's a possibility of finding it. You know, it's amazing. It's a great thing.

SPENCER MICHELS: Not all scientists go that far, but they agree that aging studies are at a crucial crossroads.