By Fran Lowry
Shortened telomere length, which is known to be associated with aging, is also associated with depression and hypocortisolism, new research shows.
These findings confirm earlier research showing shorter telomere length in depressed patients in comparison with nondepressed individuals from the general population, according to lead author Mikael Wikgren, PhD, from Umeå University in Sweden.
|Dr. Mikael Wikgren|
The study is published in the February 15 issue of Biological Psychiatry.
Dr. Wikgren's earlier work established that telomere length was associated with depression. In the current study, he and his group sought to investigate how telomere length related to biological and psychological measures of stress and whether these were related to the shorter telomere length seen in depressed patients.
The researchers measured telomere length in the leukocytes of 91 study participants who had recurrent major depressive disorder and 451 control participants. The mean age of the study participants was 59 years. Most of the depressed patients had suffered from depression for an average of 28 years.
The participants also underwent a dexamethasone suppression test to assess the reactivity of the hypothalamic-pituitary-adrenal (HPA) axis, which is a very important regulator of the stress response, most known for regulating cortisol.
Participants also filled out psychometric self-report questionnaires.
High Stress, Low Cortisol
As expected, telomere length was significantly shorter among depressed patients compared with control participants (P = .001).
Telomere length was also shorter in both depressed and control participants who showed low cortisol levels on the dexamethasone suppression test. However, it was shortest in the depressed patients.
This hypocortisolemic state was associated with a family history of affective disorders among the depressed patients and with high C-reactive protein levels among the control participants.
The researchers also found that telomere length was inversely associated with higher levels of stress as measured with the perceived stress questionnaire.
"Hypocortisolism has been found in patients with chronic fatigue syndrome, post-traumatic stress disorder, burnout, fibromyalgia, irritable bowel syndrome, disorders which share symptoms of fatigue, pain, and increased stress sensitivity," Dr. Wikgren said.
Traditionally, too much cortisol has been thought to be harmful, but more and more research is showing that the opposite is true, he added. "When you experience chronic stress, cortisol levels go down. A hyporesponsive HPA axis evolves over time when under stress, so an initially hyperreactive HPA axis gradually evolves into a hyporesponsive HPA axis."
Beyond Emotional Distress
Commenting on this research for Medscape Medical News, John H. Krystal, MD, the Robert L. McNeil Jr Professor of Translational Research and Chair of the Department of Psychiatry at Yale University School of Medicine, New Haven, Connecticut, said the current findings provide further evidence that stress and psychiatric disorders may have profound effects on health that go beyond emotional distress and functional impairment.
Dr. John Krystal
"We are learning a great deal about the functions of telomeres in processes like cellular aging and cancer," Dr. Krystal, who is also the editor of Biological Psychiatry, said.
"From this perspective, the importance of helping people to identify these life problems and to get effective treatment for them may be an important part of preserving their overall medical health. In other words, the average doctor routinely measures blood pressure, EKG, and glucose levels, but if we want to protect against some health problems, we may also need to measure depression and to assure that depressed people obtain the treatment they need."
This research was funded by the Swedish Research Council, Umeå University, and the County Councils of Västerbotten and Norrbotten, Sweden. Dr. Wikgren and Dr. Krystal have disclosed no relevant financial relationships.
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