A comparative study of autonomic reactivity in normotensive and pre-hypertensive young adult Indian males

Background: Hypertension is a non-communicable disease of major concern. Research evidence from both, animal and human studies, indicates that deranged autonomic function may contribute to development and sustenance of hypertension. Aims and Objectives: To study the progressive changes in autonomic reactivity, this study was planned to compare autonomic reactivity in normotensives and pre-hypertensives. Materials and Methods: A total of 60 (30 normotensives and 30 pre-hypertensive) young adult males participated in this study. Parasympathetic reactivity tests (expiration/inspiration ratio, 30/15 and IV/II ratios) were done using single-channel student physiograph machine. Sympathetic reactivity was tested by cold pressor test and handgrip dynamometry test. Results: There was a statistically significant increase in sympathetic reactivity by handgrip dynamometry test in pre-hypertensive participants as compared to normotensive. Furthermore, a decrease in parasympathetic reactivity was found in pre-hypertensives compared to normotensives, although values were not significant statistically. Conclusion: As the blood pressure increases, sympathetic reactivity increases while parasympathetic reactivity gradually decreases. These autonomic changes may underlie the development of human hypertension.