Mental stress induced changes in autonomic nervous activity in normotensive offsprings of hypertensive parents

Back ground: The genetic component is a major contributor in the pathogenesis of essential hypertension. Consequently the likelihood of acquiring hypertension in offspring of hypertensive parents has been estimated to be higher when compared to that of normotensive individuals. The current study is an attempt to identify the early markers for the development of hypertension in these individuals by assessing the autonomic nervous activity when subjected to mental stress. Methodology: Two groups of thirty normotensive subjects matched for age, body mass index, and physical activity were recruited.The only differentiating factor between the two groups being the genetic predisposition to hypertension of one group. Blood pressure & electrocardiogram was recorded in both groups at rest and during mental stress. Power spectral analysis of heart rate variability was done.Statistical analyses were conducted by paired & unpaired t-test. A p value of < 0.05 was considered as statistically significant. Results: A significant decrease in high frequency normalized (HFnu) in the offspring of hypertensive parents was observed at rest. During mental stress, an increase in heart rate, systolic and diastolic blood pressure was observed in both groups. Increase in low frequency normalized and decrease in HFnu in offsprings of normotensive parents and increase in LF/HF ratio in individual with hypertensive parents were observed. Difference in basal and mental stress value of heart rate and systolic pressure was significantly more and HFnu was less in offspring of hypertensives. Conclusion: Impairment in parasympathetic activity at rest and sympathovagal imbalance during mental stress is observed in individuals with hypertensive parents. This implies high chances of developing hypertension in their later life. So an evaluation of autonomic nervous activity by simple procedures like heart rate variability analysis to all individuals with a family history of hypertension in early stages of their life would prove to be invaluable. Life style modification such as regular exercises, yoga etc. can be suggested to those individuals who are found to be at the risk of developing hypertension.