Sympathoadrenal Reactivity to Stress as a Predictor of Cardiovascular Risk Factors

There is much uncertainty about the pathophysiology of essential hypertension. One possible cause may be alterations in the autonomic nervous system, which plays an important role in the normal physiological regulation of pressure. Therefore, we studied the relationship between resting blood pressure and arterial plasma catecholamines, cardiovascular and sympathetic reactivities, and cardiovascular risk factors in young men (aged 19 years) with low, normal, and high blood pressures, who were unaware of their blood pressure status. In the initial cross-sectional study, lower blood pressure was associated with a better lipoprotein profile, lower fructosamine concentration, and waist-hip-ratio. Mental stress test was the only test that induced differential responses between the 3 blood pressure groups, where the high blood pressure group showed the most and the low blood pressure group the least pronounced response in blood pressure, heart rate, and plasma catecholamines. Adrenaline and noradrenaline concentrations during mental stress test were significant predictors of future systolic blood pressure in a follow- up study over 18 years, while plasma catecholamine levels at rest and during the cold pressor test did not show significant associations with later blood pressure. Noradrenaline response to mental stress was a weak positive predictor for future waist circumference. None of the other parameters during rest or cold pressor test were significantly related to changes in Body Mass Index, waist circumference, or triceps skinfold thickness. Noradrenaline response to the cold pressor test was positively related to fasting plasma glucose and HOMA-IR at followup in univariate analyses. In the multiple regression analyses, noradrenaline response was an independent positive predictor of HOMA-IR. There were no significant associations with plasma catecholamines at rest or during mental stress test. Thus, reactivity of the sympathetic nervous system is related not only to blood pressure but also to a number of metabolic risk factors. The responses to the cold pressor test and the mental stress test seemed to have different predictive impact on the development of these risk factors.