STRESS, TELOMERES, AND AGING

by Nina

In his next post, Brad will be writing about one of the several competing theories about aging: Nobel Prize winner Dr. Elizabeth Blackburn’s theory of the relationship between aging and telomeres (the protective caps at the ends of our chromosomes). Dr. Blackburn believes that telomere length is an indicator of the age and vitality of a cell, and that psychological stress actually ages cells, which can be seen when telomere length is measured.

We thought you might be interested in Dr. Blackburn’s work because she is so convinced about the effects of stress on cellular aging that she is studying the effects of meditation and yoga on telomeres. So for those of you who would like to learn a bit about her work before Brad’s post, here is a little background information. As a start, you can find a brief interview with Dr. Blackburn here. If you’ve got an hour or so, you can listen to her lecture on “Chromosome Ends and Diseases of Aging” here.

Gaudi Mosaic by Brad Gibson

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. See here for a short article on this.

For several years, Dr. Blackburn has been conducting research on the relationship between stress and telomere length. According to her, there is so much evidence that psychological stress actually ages cells that she and her colleagues have been studying the effects of mindful meditation on telomere length. See here for a full academic paper entitled “Can meditation slow the rate of cellular aging?” I've read that as a result of these studies, Dr. Blackburn has taken up meditation as regular practice.

To be continued....

CLARIFICATION: AGING, YOGA, AND SCIENCE

by Brad

Today’s post is largely in response to the question: How would one go about investigating the effects of yoga on aging scientifically? Before tackling this question—which I will get to in the next week or two—I will first attempt to define or at least discuss a few key terms and assumptions. The reasons for this will hopefully become clear.

In the broadest the terms, “aging” applies to how systems or entities change with time. To inanimate objects, such as your new car or jacket, this begins right after it’s manufactured or, more relevantly, after you bought it.  This process of aging can be rapid or slow (weeks, months, or years), and depends a lot on what the object is and what it was designed for.  In biological systems (including us), we typically think of aging as starting after development, or post-puberty in our case.  We also tend to associate aging with a decline and/or loss of functions, both physical and mental.  However, aging can include more positive properties or phenotypes, such as increased knowledge and skill sets, and it isn’t all that hard to name a few that fit into this category. But in most biological scientific studies of aging, we refer to aging mostly in the former sense, i.e., an accumulation of mostly pathological properties, such memory loss, frailty, neurodegenerative diseases, bone loss, muscle loss, and so on. Surprisingly there are quite a few competing theories of basic aging, such as error accumulation, telomere shortening, antagonistic pleiotrophy, free-radical theory, and entropy, just to name a few. What all (or most) of these theories seek to address is the underlying molecular and physiological event that drives these largely negative processes. 

Winter Trees by Brad Gibson

The term “successful aging” is more recent, having come into wide use in the last few decades. If you want to read more about this concept, I found the first chapter in the book Successful Aging: Perspectives from the Behavioral Sciences by Paul and Margaret Baltes quite useful (for information see Cambridge ebooks). 

Even last week as I read the science section of the New York Times (see NY Times), I came across a short review of a just-published study on “Alcohol Consumption at Midlife and Successful Ageing in Women: A Prospective Cohort Analysis in the Nurses Health Study” (see PLOS).  In this prospective correlative study, researchers at Harvard demonstrated that a modest increase in successful aging for women who consumed small, but regular amount of alcohol at mid-life. (Maybe a glass of wine after yoga class isn’t such a bad idea after all?). Here they defined "successful aging" in a more precise manner: "as being free of 11 major chronic diseases and having no major cognitive impairment, physical impairment, or mental health limitations." Of course, this more operational definition to successful aging made it easier to make clear and objective distinctions among the woman in this group, typical of population based epidemiological studies. 

When we chose the term ‘healthy aging’ for this blog, the purpose was to provide information not on just how practicing yoga might help to avoid or reduce your chances of acquiring one or more of these age-related losses, but also to better manage and minimize their impact when they occur. Indeed, this is the position most of us are in, whether is through the vagaries of our genetic background, chance, past behavior, or whatever. (This reminds me of the joke: Q: What’s the best thing you can do to insure a long life? A: Choose your parents well.) So as I go back and reconsider the original question on how science can study the relationship of yoga and aging, I will reframe this question a bit: How can science study the effects of yoga on our overall physical and mental health as we age? I’ll tackle this question next time….  But as a preview, there are few good places to start, including the 2009 pilot study in Lancet on comprehensive lifestyle changes and telomere length (a biomarker of aging and cellular senescence) and several recently funded NIH studies examining yoga’s effects on depression, fatigue, and menopause. 

And please leave any questions for the Friday Q&A in the comments.