Hypertension - A Multifactorial Disorder

1. INTRODUCTION:

Hypertension is an emerging global threat to human health. It is significantly contributing to mortality and morbidity [1]. It is a chronic condition in which elevated blood pressure is observed in arteries [2]. It is also known as Essential hypertension (EH). Blood pressure is expressed in terms of systolic and diastolic pressure. Systolic blood pressure is defined as the pressure in blood vessels when heartbeats while diastolic blood pressure is defined as the pressure in blood vessels when the heart rests between the beats. In hypertensive condition, systolic blood pressure is ≥ 140mmHg and diastolic blood pressure are ≥ 90mmHg [3]. Blood pressure normally falls and rises throughout the day, but if it stays high for a long time it can damage the heart and cause serious health problems e.g. brain haemorrhage.

There are four stages of hypertension named as Pre-hypertension, Mild hypertension, Moderate hypertension and Severe hypertension. It is a common disorder that can be a risk factor for stroke, cardiovascular diseases, cerebrovascular diseases and renal failure [4, 5].

2. CAUSE OF HYPERTENSION:

2.1. ENVIRONMENTAL FACTORS LINKED WITH HYPERTENSION

It is commonly accepted that hypertension is a multifactorial and polygenetic disorder [6]. 90-95% hypertensive cases result from the complex interaction between environmental and genetic factor [7, 8]. In most cases, it’s difficult to pinpoint an exact cause of hypertension. However, there are a number of factors that contribute to hypertension. These factors include obesity, stress, lack of physical activity, diabetes, insufficient intake of potassium, smoking and alcohol consumption [9]. Lack of physical activity and obesity are directly related to hypertension. People who have less physical activity and more weight tend to have hypertension. Stress is also a major factor that contributes to hypertension by increasing the blood pressure in arteries. Insufficient intake of potassium also causes high blood pressure as intake of potassium by dietary means help to reduce or control the blood pressure level. Alcohol consumption is also a major risk factor associated with hypertension [10]. Diabetes and hypertension also tend to coexist. According to many studies, hypertension is twice as common in people who have type 2 diabetes.

The short duration of sleep is highly associated with the prevalence of hypertension in old people as lack of sleep is associated with increased activity of nervous system that leads to hypertension [11]. Another emerging factor for hypertension is noise pollution in developing countries that causes stress and shows association with hypertension. Noise pollution elevates the blood pressure and chance of hypertension is associated with the intensity and frequency of sound exposed to the people [12]. Smoking is also a major factor that causes hypertension and cardiovascular morbidity [13]. These factors are highly responsible for causing hypertension.

2.2. GENETIC VARIATION LINKED WITH HYPERTENSION:

Genetic variation is another important factor that contributes to hypertension. Thus, it can be a byproduct of genetic variants or mutation in the genes that are directly associated with the control of blood pressure. About 30% of the variation in blood pressure is due to the genetic factors [14]. Hypertension, generally transmitted in families [15]. The prevalence of hypertension is twice in people who have one or both hypertensive parents. Hypertension is 3.8 times more likely to occur among first-degree relatives [15].

By: Rimsha Zafar

3. REFERENCES:

1. Rong, S., et al., Association of G-protein β3 subunit C825T polymorphism with essential hypertension: evidence from 63 729 subjects. Journal of human hypertension, 2017. 31(8): p. 511.
2. Naish, J. and D.S. Court, Medical Sciences E-Book. 2014: Elsevier Health Sciences.
3. Russo, A., et al., Advances in the genetics of hypertension: the effect of rare variants. International journal of molecular sciences, 2018. 19(3): p. 688.
4. Health, N.I.o., National Heart, Lung, and Blood Institute Fact Book. 2005.
5. Lewington, S., et al., Age-specific relevance of usual blood pressure to vascular mortality. Author's reply.
6. Siffert, W., G protein β 3 subunit 825T allele, hypertension, obesity, and diabetic nephropathy. Nephrology Dialysis Transplantation, 2000. 15(9): p. 1298-1306.
7. Wang, W., et al., A longitudinal study of hypertension risk factors and their relation to cardiovascular disease: the Strong Heart Study. Hypertension, 2006. 47(3): p. 403-409.
8. Zheng, H., et al., Association between polymorphism of the G-protein β3 subunit C825T and essential hypertension: an updated meta-analysis involving 36,802 subjects. Biological research, 2013. 46(3): p. 265-273.
9. Aziz, K.U., Evolution of systemic hypertension in the Pakistani population. J Coll Physicians Surg Pak, 2015. 25(4): p. 286-91.
10. Zatu, M.C., et al., Alcohol intake, hypertension development and mortality in black South Africans. European journal of preventive cardiology, 2016. 23(3): p. 308-315.
11. Wu, W., et al., Sleep quality, sleep duration, and their association with hypertension prevalence among low-income oldest-old in a rural area of China: A population-based study. Journal of psychosomatic research, 2019: p. 109848.
12. Nawaz, S.K. and S. Hasnain, Noise-induced hypertension and prehypertension in Pakistan. Bosnian journal of basic medical sciences, 2010. 10(3): p. 239.
13. Virdis, A., et al., Cigarette smoking and hypertension. Current pharmaceutical design, 2010. 16(23): p. 2518-2525.
14. Beevers, G., G.Y. Lip, and E. O'Brien, The pathophysiology of hypertension. Bmj, 2001. 322(7291): p. 912-916. 
15. Hemimi, N.S.E.D., A.A. Mansour, and M.M. Abdelsalam, Prediction of the risk for essential hypertension among carriers of c825t genetic polymorphism of g protein β3 (GNB3) gene. Biomarker insights, 2016. 11: p. BMI. S38321.