RESPONSE OF THE AUTONOMIC NERVOUS SYSTEM TO MENTAL STRESS DISCRIMINATION OF RISK AND NON-RISK GROUPS

Clinical physiology, cardiology and preventive medicine need functional indicators that might position individuals at risk, and non-risk groups. Research of autonomic neural function in rest and mental stress conditions are studied to elucidate mechanisms of CVD. The aim of the present study is to examine the pattern of autonomic cardiovascular regulation at normotensive and hypertensive individuals, and to determine functional indicators that might position individuals at risk and non-risk groups. The autonomic cardiovascular control was examined with heart rate variability (HRV), and blood pressure variability (BPV) in 1069 individuals exposed to mental work load divided in two groups. In the first group, consisting of 719 individuals, results indicate that the increased level of distribution of CVD and morbidity rate enhance with the increase of the value of integral index of HRV - Health Risk (HR). A group with the highest HR value reveals the highest rate of CVD than the groups with lower HR value. A group with level of HR higher than 45% might be considered as a risk one. In the second group, consisting of 40 normotensive and hypertensive individuals selected of 350 individuals, disturbed autonomic cardiovascular control results in an increased sympathetically-mediated variances in very low frequency (VLF) bands of HRV, systolic and diastolic BPV in hypertensive compared with normotensive group under exposure to mental arithmetic tests (MA(1) and MA(2)) and colour word test (S-2). Under MA(2) and S-2 normotensives showed higher values of parasympathetic cardiac control, assessed with variance in high-frequency band of HRV than hypertensives. Increased sympathetic activity, assessed with variances in VLF and LF bands of HRV is found in hypertensives at recovery phase. Results reveal the physiological significance of VLF and LF variances of HRV as functional indicators that might position individuals at risk (AH) and non-risk (normotensive) groups. Our study indicates that HRV is a sensitive method that discriminates the pattern of autonomic cardiovascular control in risk and non-risk groups.