Most everyone over 30 is concerned with aging and age-related illnesses, like cancer and heart disease. The role of stress and cortisol in aging and chronic illness is now well established. But how increased cortisol is linked to early aging has not been clear…until very recently. Scientists at the U. of California, San Francisco have been working for a decade on the links in this chain. And, the answer is: short telomeres.
Telomeres function like a cap whose job it is to protect the end of the chromosome where the genes lie. Each time the cell divides, a bit of the telomere is cut off (instead of the gene). Dr. Elizabeth Blackburn, a molecular biologist now at UCSF, won the Nobel Prize in 2009 for her discovery of how chromosomes and genes are protected. Over time, with repeated reproduction, the telomere gets shorter. As the telomere becomes shorter, the organism begins to age and irregularities creep into the reproduction process. Some cancers may be due to these irregularities. Dr. Blackburn’s discovery was that the telomeres are actually replenished by an enzyme, telomerase reverse transcriptase.
The bad news, however, is that stress and excess cortisol damage the body’s supply of telomerase. So chronic stress can cause premature aging and illness because the constant overproduction of cortisol reduces the supply of telomerase and that prevents the cell from reversing the effects of stress. Telomere length (TL) can now be measured. However, if you are the President of the US, one does not need fancy tests to measure your TL. Stress is not the only way that telomeres become short too soon. Some people have the bad luck to be born with shorter telomeres. Others earn shorter telomeres in advance of their years by their life style choices. And, some have been exposed to early life adversities, which lead to shorter TLs over time.
The same scientists that discovered telomerase have been working on finding solutions to the harmful effects of chronic stress on DNA. In 2010, Dr. Puterman and colleagues demonstrated that moderate to vigorous physical exercise can buffer the effect of chronic stress on TL. Subjects took the Perceived Stress Scale and were divided into sedentary (not exercising) versus the active group (those getting the CDC recommended amount of daily exercise). The likelihood of having short versus long telomeres was calculated as a function of stress and exercise group, covarying age, BMI, and education. There was a significant moderating effect of exercise. Non- exercisers with even a one unit increase on the Perceived Stress Scale showed a 15-fold increase in the odds of having short telomeres, whereas for the exercisers, perceived stress was unrelated to telomere length. The conclusion is that “vigorous physical activity” (increased HR, sweating, +/or rapid breathing) appears to protect people experiencing high stress.
The USDA recommends that adults (18 to 64) do at least 2 hours, 30 minutes each week of moderate physical activity (brisk walking, dancing) OR 1 hour, 15 minutes each week of aerobic physical activity at a vigorous level (running, walking fast uphill, cycling). Being active 5 hours or more a week can provide even more health benefits. It is recommended that the physical activity be spread out over at least 3 days a week and that each activity should last at least 10 minutes at a time. Strengthening exercises are also recommended, like sit ups, weights, at least 2 days a week to maintain memory.
In sum, as you age, it is essential to protect your telomere length by a minimum of 25 minutes at least 3 days a week of vigorous exercise. Next month we will look at how the damage of chronic stress to DNA can be inherited or transferred to the next generation.
by Susan Andrews, PhD
The Psychology Times, December 2014
Dr. Susan Andrews, Clinical Neuropsychologist, is currently Clinical Assistant Professor, LSU Health Sciences Center, Department of Medicine and Psychiatry, engaged in a Phase III study on HBOT and Persistent PostConcussion Syndrome. In addition to private clinical practice, Dr. Andrews is an award-winning author of Stress Solutions for Pregnant Moms (2013).