Papers by Dirk Hellhammer
The Journal of Clinical Endocrinology & Metabolism, 2004
Fifty-eight male twin pairs aged 16 -24 yr (mean age 18.67 yr, sd 2.29) were recruited for partic... more Fifty-eight male twin pairs aged 16 -24 yr (mean age 18.67 yr, sd 2.29) were recruited for participation in this experiment by mail. Postal addresses of potential twin pairs (pairs of individuals with identical dates of birth, birthplaces, and family names) were supplied by the residents' registration office (Daten-und Informationszentrum; DIZ) of Rheinland-Pfalz, Germany. As confirmed by subsequent DNA analysis (see below), the sample consisted of 33 monozygotic (MZ) and 25 dizygotic (DZ) twin pairs, each raised together in the same household. Before entering the Abbreviations: AUC, Area under the response curve; c 2 , contribution of shared environment; DZ, dizygotic; e 2 , contribution of environment and measurement error; GR, glucocorticoid receptor; h 2 , contribution of genetic factors; HPA, hypothalamus-pituitary-adrenal; HR, heart rate; MZ, monozygotic; r i , intrapair correlation coefficient; TSST, Trier Social Stress Test.
Psychoneuroendocrinology, 1990
In two studies we applied a new stochastic model for the measurement of latent states and traits ... more In two studies we applied a new stochastic model for the measurement of latent states and traits to salivary cortisol in healthy subjects. Data were analyzed by Linear Structural Relations (LISREL). In the first study, 48 students collected saliva samples on two occasions at 1300h with an interval of six weeks between occasions. Salivary cortisol levels were found to be mainly influenced by situational and/or interactional effects, which determined approximately 75% of the total variance of the hormone data, while only approximately 21% were determined by the latent trait. Measurement unreliability was found to be approximately 4%.
Behavior Genetics, 2010
Cortisol is an indicator of hypothalamic-pituitary-adrenal axis responsivity to stress, but few t... more Cortisol is an indicator of hypothalamic-pituitary-adrenal axis responsivity to stress, but few twin studies have examined the heritability of cortisol concentrations in adults across the diurnal cycle and in different contexts. Saliva samples were provided by 783 middleaged male twins on one laboratory and two home days as part of the Vietnam Era Twin Study of Aging. Significant cortisol heritability estimates were found for laboratory measures only: awakening (.56); 30 min after awakening (.48); 1000 h (.42); mean output across the day (.43); and mean cortisol awakening response (.64). Twin correlations at home were low. In the laboratory, they were unchanged for fraternal twins, but increased for identical twins. Greater measurement error at home did not appear to account for home-laboratory differences. The results suggest that genetic factors influence cortisol responses to specific environmental stressors. Thus, cortisol levels are correlated in identical twins only when they undergo similar experiences.
Journal of Affective Disorders, 2008
Biological Psychology, 2008
A considerable variability in the sensitivity to glucocorticoids (GCs) exists between individuals... more A considerable variability in the sensitivity to glucocorticoids (GCs) exists between individuals and these differences have been implicated in the etiology of psychiatric diseases such as depression. Glucocorticoid receptor (GR) gene polymorphisms might account in part for variability in GC responsiveness. We assessed the association between four common GR gene (NR3C1) polymorphisms (ER22/23EK, N363S, BclI, 9beta) and markers of glucocorticoid sensitivity in two target tissues (subdermal blood vessels, peripheral leukocytes) in 206 healthy individuals. The BclI GG genotype group showed the least degree of skin blanching, reflecting a lower GC sensitivity of subdermal blood vessels (p=.01). No association between GR genotype and GC sensitivity of peripheral leukocytes was observed. In the same subjects we previously observed an association between GR genotype and GC sensitivity of the pituitary. Polymorphism of the GR gene might constitute a vulnerability or protection factor for stress related disorders and altered GC sensitivity.
Objective: Results from animal and human studies suggest that disregulations of the hypothalamus-... more Objective: Results from animal and human studies suggest that disregulations of the hypothalamus-pituitary-adrenal (HPA) axis are involved in several behavioral, circulatory, endocrine, and immune disorders with clear-cut gender differences in disease prevalence. The aim of the present study was to investigate sex-specific HPA response patterns with a focus on the contribution of gonadal steroids as possible mediators. Methods: A total
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Papers by Dirk Hellhammer