Showing posts with label aging theories. Show all posts
Showing posts with label aging theories. Show all posts

Can Meditation Delay Aging?

12:41 | Labels: , , , ,

by Brad and Nina 

Gaudi Ceiling by Brad Gibson
Since the early days of Yoga for Healthy Aging, we’ve been blogging about the research of Dr. Elizabeth Blackburn, who studies the effects of stress on cellular aging (see Stress, Telomeres and Aging). Dr. Blackburn is so convinced that chronic stress affects aging on a cellular level that she is studying the effects of meditation and yoga on aging, thinking that these practices might actually slow aging and lengthen life.

In particular, Dr. Blackburn has been studying the affects of meditation and yoga on telomere length. Throughout your life, your cells may reproduce many times to repair and strengthen their host organs, to grow or to fight disease, and the telomere at the end shrinks each time the cell divides and duplicates itself. A chemical called telomerase helps restore a portion of the telomere with each division, but after 10 to 50 divisions or so (the number varies by tissue type and health, and biologists still do not understand the system well), the telomere gets so short that the cell is no longer able to replicate. Because some cells or tissues in our body (skin, blood cells, etc.) continue to replicate and be replaced as we age, or to be repaired after injury, if the progenitor cells needed for these processes cannot replicate due to telomere shortening, this can contribute to the aging process and increase our susceptibility to disease.

Dr. Blackburn’s research has demonstrated that chronic stress actually accelerates telomere shortening and that anti-stress practices such as meditation and yoga can in turn slow the process by “boosting” telomeres. A recent BBC article Can Meditation Delay Aging?  gives a good overview of Dr. Blackburn’s current research. Here’s an excerpt that explains why meditation and yoga might boost telomeres.

Theories differ as to how meditation might boost telomeres and telomerase, but most likely it reduces stress. The practice involves slow, regular breathing, which may relax us physically by calming the fight-or-flight response. It probably has a psychological stress-busting effect too. Being able to step back from negative or stressful thoughts may allow us to realise that these are not necessarily accurate reflections of reality but passing, ephemeral events. It also helps us to appreciate the present instead of continually worrying about the past or planning for the future.
But while telomeres are still getting a lot of buzz these days, I for one know that this is only one of many theories of aging out there (see What is Aging, Anyway?). So I turned to Brad for his take on the article (and the issue of telomeres in general). 

—Nina

Overall, this a reasonable, well-written and—for the most part—balanced article. I think when it gets into how the established medical profession and scientists are reluctant to get into this area, it is largely correct. However, there is so much confusion and outright snake oil sales in the “anti aging” field right now that it’s no big mystery why people (and scientists) are cautious. In addition, it is important to keep in mind that the role of telomeres in aging is still very controversial. This statement late in the article is a bit problematic:

"Conventional medical tests give us our risk of particular conditions - high cholesterol warns of impending heart disease, for example, while high blood sugar predicts diabetes. Telomere length, by contrast, gives an overall reading of how healthy we are: our biological age. And although we already know that we should exercise, eat well and reduce stress, many of us fall short of these goals."

For one, the role of cholesterol levels is (surprise!) being hotly debated again. And some of the longstanding wisdom about what levels are good or bad—especially for women—may be wrong.  The idea that telomere length is a read-out of our “biological age” is simply not supportable by solid scientific evidence. It is telling us something, but it’s not exactly clear what that is precisely. There are some big efforts going on right now to identify new “biomarkers” of aging, and I'm under the impression that telomere length is no longer being considered as major player in these efforts.

—Brad


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The Key to Reversing Aging. Or Not.

13:53 | Labels: , ,


by Nina

A Mouse as a Monk by Shibata Zeshin
“It is quite possible that it will dramatically increase the incidence of cancer,” said Irina M. Conboy, a professor of bioengineering at the University of California, Berkeley. “You have to be careful about overselling it.” —New York Times

As if to prove one of the points I made in my post just last Monday What is Aging, Anyway?, a recent article in the New York Times announced a new study on aging research Young Blood May Hold Key to Reversing Aging. Yes, they went right ahead and used the “r” word, one of the words that I said should set of alarm bells.

But I try to keep up with the latest developments in research on aging and the article was the New York Times after all, so I went ahead and read it (oh, the things I’m forced to do for this blog). Of course, the “young blood” thing turned out to be more complex than headline implied. In fact, the research was specifically about adult stem cells—in mice, of course.

Adult stem cells keep our tissues healthy. When there is damage to a part of the body, stem cells move in and produce new cells to replace the dying ones. But as we—and mice—get older, our stem cells don’t work as well. (Have you noticed how much longer it takes to for you to heal after a muscle tear or even a simple scrape?) It’s not that the number of stem cells is lower in older bodies, it’s just that, as Thomas A. Rando, professor of neurology at Stanford University School of Medicine put it, “They just don’t get the right signals.”

Wondering what signals the old stem cells would receive if they were bathed in young blood, Dr. Rando and his colleagues experimented by joining old and young mice for five weeks (literally joining them together—see NY Times article for the gruesome details). After five weeks, the muscles of the old mice had healed about as quickly as those of the young mice, and the old mice had grown new liver cells at the rate of younger mice. What could be causing this? A member of Dr. Rando’s team, Dr. Wagers continued to study the blood of young mice after she moved in 2004 to Harvard, and last year she and her colleagues demonstrated that the young blood could rejuvenate the hearts of old mice. After they found that a protein called GDF11 that was abundant in young mice and scarce in old ones, the scientists injected GDF11 into old mice. And they found that even on its own, GDF11 had the same positive effective the hearts of the old mice. Then they did a similar experiment on skeletal muscle in mice, and found that GDF11 revived stems cells in old muscles as well, making old mice stronger and increasing their endurance.

At this point, I was actually feeling—despite the ultra gross details of how the old and young mice were sewn together—a bit excited. Imagine if we could take some kind of GDF11 supplement that would rejuvenate our aging organs, muscles and bones? But, WAIT! At the very end of the article, the author concluded by saying that scientists would need to take care in rejuvenating old body parts—waking up stem cells might lead to their multiplying uncontrollably. Hence the Conboy quote at the beginning of this post, warning of possible increases in cancer. Skepticism turned back to the ON position, I consulted our resident expert on aging Dr. Brad Gibson for his opinion on this latest claim about “Reversing” aging. And here’s what he said:

"I would agree with Conboy about the possibility for adverse effects. Especially cancer, as there is growing evidence for the role of dormant stem cells that become activated in breast and other cancers leading to metastasis.  And if young blood—now containing among other things an elevated level of GDF11—is introduced into an aged background, are we going to be stimulating (previously dormant) cancerous stem cells as well?

"It's akin to if we just now had discovered human growth hormone (hGH) and realized that it too goes down with age, and increasing would restore some young phenotype (more energy, more muscle mass, etc.). Turns out hGH has lots of bad side effects—including an increased risk of cancer as well as cardiovascular diseases —and it also was once (and still is to some) claimed as a 'rejuvenating" or 'anti-aging' substance.  Overall, very interesting and potentially ground breaking science, but it begs the question why we feel compelled to go around making absurd and/or over-reaching claims before we really know about its other effects? It’s possible that GDF11 levels go down with age to limit cancer stem cell becoming activated, albeit at a high price of a loss of tissue repairs capabilities. Or not..." 

Excuse me while I go practice a yoga for upper body strength sequence now….

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What is Aging, Anyway?

08:26 | Labels: , ,


by Nina

Death and Life by Gustav Klimt
We all experience aging as we move through time, from that first gray hair to the need for reading glasses or a twinge of arthritis to more dramatic changes. Eventually our bodies just don’t work as well as they did when we were young. (A formal definition of aging is “the process of a system’s deterioration over time.”) But have you ever wondered what causes aging? Or why human beings have the life span that they do? After all, a worm lives for only 10 days, a mouse for one or two years, and a dog typically over 10 years. Some kind of clockwork causes all living things to gradually age—yes, even worms get wrinkly when they get “elderly”— according to an apparent built-in schedule. But why does this all happen? And is there anything we can do about it?

When Dr. Bradford Gibson first joined the Buck Institute for Research on Aging, he was looking forward to finding the answers to those questions. Much to his surprise, he discovered that there are many different and often conflicting theories of aging. He had somewhat naively assumed that there must be some general consensus on the basic questions of how and why we age. But, he says:

“As I examined theories such as the free radical theory of aging to antagonistic pleiotrophy, it became readily apparent that this was still early days of this discipline. While many of the processes described in these competing theories seemed plausible, they couldn’t all be correct. So working in this field was going to be much more confusing— and interesting — than I had originally imagined.”

Since you might have read about telomere shortening or caloric restriction in the news, here’s a list of some of the theories of aging that Dr. Gibson confronted when he first joined the Buck Institute (with the ones he currently thinks most likely to be important in bold).
  • Wear and Tear theory
  • Error and Repair theory
  • Neuroendoncrine theory
  • Redundant DNA theory
  • Genetic Control theory
  • Free Radical theory
  • Caloric Restriction/Nutrition
  • Cross-Linking
  • Waste Accumulation
  • Gene Mutation
  • Limited No. of Cell Divisions/Telomere Shortening
  • Rate of Living
  • Hayflick’s Limit theory
  • Order to Disorder (entropy)
  • Death Hormone
  • Thymic-stimulatory theory
  • Mitochondrial theory
  • Autoimmune theory
  • Antagonistic Pleiotrophy

That’s quite a list, isn’t it? But that’s not all; newer data have emerged in the last few years that have shown the importance of stem cell maintenance, modifications to your DNA (epigenetics), and senescence-associated inflammation as playing key roles in the aging process. I’m sharing all this with you for a couple of reasons. First of all, if someone out there tells you they can “stop” or even “reverse” aging—I've heard both claims myself—you should be very skeptical. Because right now with so much unknown about aging, there is no proof that any of these anti-aging solutions are effective (and, in some cases, like overuse of certain supplements or human growth hormones, they could actually harm you). And, second, I want to set your expectations. This blog has always been about healthy aging, never about stopping or reversing aging.


I’m going to be defining “healthy aging” and writing more about what it means in future posts, but, for now, you can check out my post Longevity vs. Morbidity (Ill Health). 

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Aging, Telomeres, and Yoga: New Study by Elizabeth Blackburn and Dean Ornish

12:34 | Labels: , , , ,

by Baxter

A while back, we reported on an interesting potential marker in the body for aging of the cells connected to the genes called a telomere (see Stressed Mind, Stressed Cells and Science, Aging and Yoga). A telomere is like a tail on the end of DNA strands found in our cells, and an enzyme called telomerase influences the length and activity of the telomere. Studies done a few years ago by a Dr. Elizabeth Blackburn at UCSF in San Francisco began to show a connection between telomeres and cell longevity—the longer the telomere, the longer the cell life. Her work garnered her a Nobel Prize in Medicine.

Telomere Caps
Now Dr. Blackburn has teamed up with Dr. Dean Ornish to see what effect his life-style changes approach to prostate cancer has on telomeres and telomerase activity. Dr. Ornish has already shown that a combination of dietary changes (vegan diet with less than 10% fat per day), exercise in the form of walking for 30 minutes most days, and stress management tools that include regular yoga asana and breath work, mindfulness meditation and once a week group stress reduction sessions can reverse heart disease and diabetes, and can stabilize prostate cancer and stop its progression.

In their most recent study, published in Lancet Oncology (see Effect of comprehensive lifestyle changes on telomerase activity and telomere length in men with biopsy-proven low-risk prostate cancer: 5-year follow-up of a descriptive pilot study), the two researchers looked at how the lifestyle program impacted the cellular genetic level in regards to telomere length and enzyme activity. What they found was that the 10 men studied had longer telomeres in the short (as quickly as three months!) and long run, if they stuck to the program, and the 25 men who were controls had shorter telomeres. And they also looked at gene activity in their ten study subjects, and found that 500 genes were turned on, and all were beneficial, according to Ornish. 

Even though telomeres may be an indicator of longer cell life, and by extension, longer overall lifespan, this has not been definitively concluded, so more studies will need to be done, looking at much larger numbers of people. But the early evidence is promising, and even if the telomere/aging cell theory does not pan out, it seems evident that yoga, diet, exercise and stress management do have significantly positive impacts on health, disease progress or remission, and are therefore worth the effort. And as Dr. Ornish noted, his study participants found the lifestyle plan easy to follow, with 85-90% compliance, much better than most pharmaceutical based treatment plans. Why, you might ask? Well, has he says, it’s because it’s pleasant and comprehensive and “most people feel so much better they change their lifestyle.”

To read more, you can check out articles at ucsf.edu and today.com—among others—which reported these new findings.


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