Stress and cellular aging Associations between stress-related factors and leukocyte telomere length
Year: 2016
Type: dissertation
Study design: Observational Study
Abstract: It is well established that stress poses an elevated risk for non-communicable diseases and early mortality. However, the underlying mechanisms are not fully understood. There is strong, yet not conclusive, evidence showing that telomeres, non-coding DNA-protein complexes (TTAGGG) located at the end of chromosomes, are associated with aging-related diseases including cardiovascular diseases, stroke and type 2 diabetes. The aim of this thesis is to expand the relatively scant literature on stress and telomere length and to study whether stress-related factors are associated with leukocyte telomere length (LTL), a possible biomarker of cellular aging. The participants were from the Helsinki Birth Cohort Study, which comprises 13,345 individuals born from 1934 to 1944 in Finland. Between the years 2001 and 2004 a randomly selected sample of subjects participated in a detailed clinical examination including blood sampling for LTL measurement. LTL data, measured by the quantitative Polymerase Chain Reaction (qPCR) method, was available for 1964 participants (men n = 912 and women n = 1052) at a mean age of 61.5 (SD = 2.9, Range = 56.7 - 69.8) years. In conjunction with the clinical examination, the participants reported on the following stress-related factors: the Beck Depression Inventory (n = 1954), the Mental Health Index (n = 1950) and the Vitality Scale (n = 1950) from the SF36/RAND to capture depressive symptoms. After clinical examination they completed the NEO Personality Inventory (n = 1671) to capture personality dimensions that either render individuals vulnerable to or buffer them from stress and the Traumatic events checklist (n = 1486) to capture traumatic experiences across the lifespan. Objective stress-related factors were derived from Finnish registries. These included mental disorders (n = 116 vs. 1840), sleep apnea (n = 44 vs. 1875) and snoring (n = 29 vs. 1875) that were identified from the Finnish Hospital Discharge Register, psychotropic medication use (n = 665 vs. 1291) that was identified from the Finnish National Social Insurance Institution Register, and early life stress (n = 215 vs. 1271), namely temporary separation from both parent(s) due to child evacuations from Finland during World War II, that was identified from the National Archives register. In addition, a subsample of the participants with LTL measurement underwent the Trier Social Stress Test (n = 287) during which HPA axis stress reactivity was measured. The results showed no associations between personality dimensions, mental disorders, depressive symptoms, objectively measured early life stress, self-reported traumatic experiences across the lifespan, or HPA axis stress reactivity and LTL. However, a combination of objectively measured early life stress and self-reported traumatic experiences, and a history of sleep apnea, were associated with shorter LTL. Two unpredicted findings were also made. Individuals hospitalized for mental disorders who also used psychotropic medication had longer LTL than non-hospitalized controls; also an agreeable personality dimension was associated with LTL in a sex-specific manner such that more agreeable men and less agreeable women had shorter LTL. As a majority of the findings did not support the study hypotheses, and the effect sizes in the few existing associations were relatively small, the results in this PhD thesis suggest that stress related factors are not strongly associated LTL, at least when measured with qPCR in an elderly sample showing little variation in age.
Source: Työväentutkimus Vuosikirja
Author: Katri Savolainen
Language: English
Subfield: Cell Biology
Domain: Life Sciences
Open Access status: green
OpenAlex ID: W2528301378