Over the past few decades, researchers have quantified many of the effects of stress on the human body, from frequent headaches, muscle pain or spasm to chest palpitations, while emotional and cognitive signs involve memory impairments, anxiety, moodiness and depression.
In a new study, researchers focus on the unseen effects of stress — damage to the cellular fabric of the human body that may speed the aging process.
Researchers looked at the way in which stress can shorten telomere length. Telomeres are protective caps on the ends of chromosomes and are indicators of aging, as they naturally shorten over time.
However, telomeres are also highly susceptible to stress and depression, both of which have repeatedly been linked with premature telomere shortening.
The human stress response is regulated by the hypothalamic-pituitary-adrenal axis, or HPA axis. This region controls the body’s levels of cortisol, the primary stress hormone. Unfortunately, the HPA axis does not work normally in individuals with depression — and stress-related illnesses.
In the study, scientists reviewed the relationships between telomere length, stress, and depression, measuring telomere length in patients with major depressive disorder and in healthy individuals. They also measured stress, both biologically, by measuring cortisol levels, and subjectively, through a questionnaire.
They found that telomere length was shorter in the depressed patients, which confirmed prior findings. Importantly, they also discovered that shorter telomere length was associated with a low cortisol state in both the depressed and healthy groups.
These findings suggest a link between stress, depression and aging.
First author Mikael Wikgren, Ph.D., explained, “Our findings suggest that stress plays an important role in depression, as telomere length was especially shortened in patients exhibiting an overly sensitive HPA axis. This HPA axis response is something which has been linked to chronic stress and with poor ability to cope with stress.”
According to Dr. John Krystal, editor of Biological Psychiatry,“The link between stress and telomere shortening is growing stronger. The current findings suggest that cortisol levels may be a contributor to this process, but it is not yet clear whether telomere length has significance beyond that of a biomarker.”
Researchers say additional studies are necessary to determine if interventions to stabilize or normalize telomere length would improve outcomes.