Although a functioning stress response is absolutely essential in fight-or-flight situations, chronic activation of this response can eventually have detrimental effects on physical health. For instance, many chronically stressed individuals have shorter telomeric DNA on the ends of chromosomes. High levels of cortisol have been shown to cause oxidative stress damage and to dampen the activity of telomerase, which adds DNA sequence repeats with each cell division. Short telomeres are unfavorable because they can ultimately prevent cells from multiplying and functioning normally.
In the case of immune system cells, critically short telomeres can cause a loss of antigen recognition in leukocytes. Tyrka et al. (2010) tested the length of leukocyte telomeres in 31 adults who reported varying degrees of childhood maltreatment. After controlling for age, sex, smoking status, BMI, level of education, medical or psychiatric illness, and childhood socioeconomic adversity, the maltreatment group had significantly shorter telomeres than the group reporting no childhood maltreatment. Hence, even long-past childhood events have the potential to disrupt proper immune function.
However, exercise can be a useful deterrent of telomere shortening, according to Puterman et al. (2010). For 63 healthy post-menopausal women, the relationship between telomere length (TL) and the amount of time spent exercising per week was tested. Participants who vigorously exercised at least 75 minutes per week were labeled as “active” and the others were labeled as “sedentary.” This is the amount of time recommended by the Centers for Disease Control (CDC). Participants with higher perceived stress were significantly less likely to be “active,” had shorter TL, a higher body mass index and fewer years of education. After controlling for age, BMI, education, and antioxidant vitamin use, the authors found that exercise was able to significantly buffer telomere shortening. Although excessive exercise can promote cell damage, this study makes it clear that a reasonable amount of exercise per week can greatly reduce the effects of stress on premature cellular aging.
Puterman et al. (2010). The power of exercise: Buffering the effect of chronic stress on telomere length. PLoS ONE, 5(5), 1-6.
Tyrka et al. (2010). Childhood maltreatment and telomere shortening: Preliminary support for an effect of early stress on cellular aging. Biological Psychiatry, 67(6), 531-534.
It's amazing how chronic stress can affect us on a molecular and cellular level. I found a video on youtube describing how stress affects our telomeres. This short video focused on a cohort of moms who were under chronic stress because of the stress associated with being a mother of a disabled child. Data showed that the length of telomeres are correlated to the amount of stress each mother was under and for how long they experienced chronic stress. Approximately one year of chronic stress leads to 6 years of aging.
ReplyDeleteThis video also comments about an enzyme that helps repair telomere damage, telomerase. Preliminary data suggests that meeting or connecting with other humans can help stimulate the healing affects of this enzyme.
An article that I found was interested in analyzing the effect telomerase had upon cells. Not only did research shows that when mice who lack this enzyme tended to age faster but once the enzyme was reintroduced into their cells, the telomerase reversed cell damage!!!! Mice with exposure to telomerase for one month, grew larger brains compared to the mice who did not have the enzyme telomerase and other organs also recuperated.
This is amazing research and could benefit us someday!
http://www.youtube.com/watch?v=cvjzwTBjXMI
http://www.nature.com/news/2010/101128/full/news.2010.635.html