— leukocytes = a type of immune system cells
— telomeres = things at the end of your DNA strands, their length is used to measure the rate of aging of certain cells
“Reduced leukocyte telomere length has been found to be associated with multiple common age-related diseases, including heart disease, diabetes, and cancer. A link has also been suggested between shortened leukocyte telomere length and major depressive disorder, suggesting that major depressive disorder may be a disease of accelerated aging.”

“This prospective, longitudinal study examined the association between depression diagnosis at baseline and change in leukocyte telomere length over two years in a well-characterized sample of N = 117 adults with or without major depressive disorder at baseline, using rigorous entry criteria.”

“Participants aged 18–70….”

“Individuals with major depressive disorder at baseline had greater leukocyte telomere length shortening over two years than individuals without major depressive disorder, even after controlling for differences in age, sex, and body mass index.”

“A baseline diagnosis of major depressive disorder prospectively predicted leukocyte telomere length shortening over two years. Our results provide further support for major depressive disorder as a disease associated with accelerated aging……”
M.C.Vance, et al
Prospective association between major depressive disorder and leukocyte telomere length over two years
Psychoneuroendocrinology – Volume 90 – April 2018 – page 157