Genetic modeling of the relationship between neuroticism and 24-hour profiles of autonomic heart function, blood pressure and cortisol

Researcher: Ms. H.M. (Nina) Kupper

Depression possibly co-occurs with a dysfunction of the three major axes of the autonomic nervous system that regulate the bodily homeostasis: the sympathetic and parasympathetic nervous system and the Hypothalamus Pituitary Adrenal (HPA) axis. The latter regulates the “stress” system, and causes the excretion of the hormone cortisol.  This study investigated the activity of these three axes in a real life setting. This means that selected twins and their brothers/sisters underwent a 24-hour measurement of heart action and blood pressure. In addition, saliva sampling during the test day gave a diurnal profile of cortisol for each participant.  Parameters were: systolic and diastolic blood pressure, heart rate, heart rate variability, pre-ejection period (PEP), respiration sinus arrhythmia (RSA) and basal cortisol. In the study baseline levels, lability, reactivity and recovery of hormone, heart action and blood pressure variables have been taken into account. Statistical analysis of the collected and selected data (comparing monozygotes with dizygotes and sibling pairs) have lead to an estimate of the influence of genes and environment on the measured variables. Furthermore, the association between physiological dysfunction and anxious depression were tested on a common genetic factor. The results of this analysis may contribute to future linkage and association research on genes for anxiety and depression.

Ms Kupper started her research in July 2001. A total of 800 people have undergone measurements. The research was completed in July 2005.