Telomere length - a cellular aging marker for depression and Post-traumatic Stress Disorder.

Telomeres play a central role in cell fate and aging by adjusting the cellular response to both biological and psychological stress. Human telomeres are regions of tandem TTAGGG repeats at chromosomal ends that protect chromosomes from degradation, fusion, and recombination. They are made up of approximately 1000-2500 copies of the repeated DNA sequence. Over time, at each cell division, the telomere ends become shorter. Thus, telomere length (TL) has been considered a cellular marker for age-related diseases. In addition to biochemical stressors such as oxidation and inflammation, psychosocial traumatic stress has also been linked to shorter telomeres. TL is significantly inversely correlated with long-term depression, even after controlling for age. Average TL in depressed subjects, who were above the median of lifetime depression, was 281 base pairs shorter than that in controls, corresponding to approximately 7years of accelerated cell aging. Several recent studies have also demonstrated an inverse relationship between leukocyte telomere length (LTL) and the risk of PTSD. TL was inversely correlated with the duration of caregiving and PTSD. Here, we focus on the discussion of findings in studies of the relationships between stress-related disorders (e.g., depression and PTSD) and telomeres. We also present direct evidence that TL is associated with traumatic stress, depression, and PTSD, and hypothesize that traumatic stress affects not only mental disorders but also cellular aging. The nature of this relationship between stress and TL warrants further evaluation in psychiatry. Published by Elsevier Ltd.