Dr Martin Juneau, M.D., FRCP
Cardiologue et Directeur de la prévention, Institut de Cardiologie de Montréal. Professeur titulaire de clinique, Faculté de médecine de l'Université de Montréal. / Cardiologist and Director of Prevention, Montreal Heart Institute. Clinical Professor, Faculty of Medicine, University of Montreal.See all articles
- Hypertension is the main risk factor for cardiovascular disease and is responsible for 20% of deaths worldwide.
- Early hypertension, before the age of 45, is associated with an increased risk of cardiovascular disease, cognitive decline and premature mortality.
- Adopting an overall healthy lifestyle (normal weight, not smoking, regular physical activity, moderate alcohol consumption, and a good diet including sodium reduction) remains the best way to maintain adequate blood pressure.
According to the latest data from the Global Burden of Disease Study 2019, excessively high blood pressure was responsible for 10.8 million deaths worldwide in 2019, or 19.2% of all deaths recorded. This devastating impact is a direct consequence of the enormous damage caused by hypertension on the cardiovascular system. Indeed, a very large number of studies have clearly shown that excessive blood pressure, above 130/80 mm Hg (see box for a better understanding of blood pressure values), is closely linked to a significant increased risk of coronary heart disease and stroke.
Systolic and diastolic
It is important to remember that blood pressure is always expressed in the form of two values, namely systolic pressure and diastolic pressure. Systolic pressure is the pressure of the blood ejected by the left ventricle during the contraction of the heart (systole), while diastolic pressure is that measured between two beats, during the filling of the heart (diastole). To measure both pressures, the arterial circulation in the arm is completely blocked using an inflatable cuff, then the cuff pressure is allowed to gradually decrease until blood begins to flow back into the artery. This is the systolic pressure. By continuing to decrease the swelling of the cuff, we then arrive at a pressure from which there is no longer any obstacle to the passage of blood in the artery, even when the heart is filling. This is the diastolic pressure. A blood pressure value of 120/80 mm Hg, for example, therefore represents the ratio of systolic (120 mm Hg) and diastolic (80 mm Hg) pressures.
As shown in Figure 1, this risk of dying prematurely from coronary heart disease is moderate up to a systolic pressure of 130 mm Hg or a diastolic pressure of 90 mm Hg, but increases rapidly thereafter to almost 4 times for pressures equal to or greater than 150/98 mm Hg. This impact of hypertension is even more pronounced for stroke, with an 8 times higher risk of mortality for people with systolic pressure above 150 mm Hg and 4 times higher for a diastolic pressure greater than 98 mm Hg (Figure 1, bottom graph). Consequently, high blood pressure is by far the main risk factor for stroke, being responsible for about half of the mortality associated with this disease.
Figure 1. Association between blood pressure levels and the risk of death from coronary heart disease or stroke. From Stamler et al. (1993).
Blood pressure tends to increase with aging as blood vessels become thicker and less elastic over time (blood circulates less easily and creates greater mechanical stress on the vessel wall). On the other hand, age is not the only risk factor for high blood pressure: sedentary lifestyle, poor diet (too much sodium intake, in particular), and excess body weight are all lifestyle factors that promote the development of hypertension, including in younger people.
In industrialized countries, these poor lifestyle habits are very common and contribute to a fairly high prevalence of hypertensive people, even among young adults. In Canada, for example, as many as 15% of adults aged 20–39 and 39% of those aged 40–59 have blood pressure above 130/80 mm Hg (Figure 2).
Figure 2. Prevalence of hypertension in the Canadian population. Hypertension is defined as systolic pressure ≥ 130 mm Hg or diastolic pressure ≥ 80 mm Hg, according to the 2017 criteria of the American College of Cardiology and the American Heart Association. The data are from Statistics Canada.
This proportion of young adults with hypertension is lower than that observed in older people (three in four people aged 70 and over have hypertension), but it can nevertheless have major repercussions on the health of these people in the longer term. Several recent studies indicate that it is not only hypertension per se that represents a risk factor for cardiovascular disease, but also the length of time a person is exposed to these high blood pressures. For example, a recent study reported that onset of hypertension before the age of 45 doubles the risk of cardiovascular disease and premature death, while onset of hypertension later in life (55 years and older) has a much less pronounced impact (Figure 3). These findings are consistent with studies showing that early hypertension is associated with an increased risk of cardiovascular mortality and damage to target organs (heart, kidneys, brain). In the case of the brain, high blood pressure in young adults has been reported to be associated with an increased risk of cognitive decline at older ages. Conversely, a recent meta-analysis suggests that a reduction in blood pressure with the help of antihypertensive drugs is associated with a lower risk of dementia or reduced cognitive function.
Figure 3. Change in risk of cardiovascular disease (red) or death from all causes (blue) depending on the age at which hypertension begins. Adapted from Wang et al. (2020).
Early hypertension should therefore be considered an important risk factor, and young adults can benefit from managingtheir blood pressure as early as possible, before this excessively high blood pressure causes irreparable damage.
The study of barbershops
In African-American culture, barbershops are gathering places that play a very important role in community cohesion. For health professionals, frequent attendance at these barbershops also represents a golden opportunity to regularly meet Black men to raise their awareness of certain health problems that disproportionately affect them. This is particularly the case with hypertension: African American men 20 years and older have one of the highest prevalence of high blood pressure in the world, with as many as 59% of them being hypertensive. Also, compared to whites, Black men develop high blood pressure earlier in their lives and this pressure is on average much higher.
A recent study indicates that barbershops may raise awareness among African Americans about the importance of controlling their blood pressure and promoting the treatment of hypertension. In this study, researchers recruited 319 African Americans aged 35 to 79 who were hypertensive (average blood pressure approximately 153 mm Hg) and who were regular barbershop customers. Participants were randomly assigned to two groups: 1) an intervention group, in which clients were encouraged to see, in the barbershops, pharmacists specially trained to diagnose and treat hypertension and 2) a control group, in which barbers suggested that clients make lifestyle changes and seek medical attention. In the intervention group, pharmacists met regularly with clients during their barbershop visits, prescribed antihypertensive drugs, and monitored their blood pressure.
After only 6 months, the results obtained were nothing short of spectacular: the blood pressure of the intervention group fell by 27 mm Hg (to reach 125.8 mm Hg on average), compared to only 9.3 mm Hg (to reach 145 mm Hg on average) for the control group. Normal blood pressure (less than 130/80 mm Hg) was achieved in 64% of participants in the intervention group, while only 12% of those in the control group were successful. A recent update of the study showed that the beneficial effects of the intervention were long-lasting, with continued pressure reductions still observed one year after the start of the study.
These reductions in blood pressure obtained in the intervention group are of great importance, as several studies have clearly shown that pharmacological treatment of hypertension causes a significant reduction in the risk of cardiovascular diseases, including coronary heart disease and stroke, as well as kidney failure. This study therefore shows how important it is to know your blood pressure and, if it is above normal, to normalize it with medication or through lifestyle changes.
The importance of lifestyle
This last point is particularly important for the many people who have blood pressure slightly above normal, but without reaching values as high as those of the participants of the study mentioned above (150/90 mm Hg and above). In these people, an increase in the level of physical activity, a reduction in sodium intake, and body weight loss can lower blood pressure enough to allow it to reach normal levels. For example, obesity is a major risk factor for hypertension and a weight loss of 10 kg is associated with a reduction in systolic pressure from 5 mm to 10 mm Hg. This positive influence of lifestyle is observed even in people who have certain genetic variants that predispose them to high blood pressure. For example, adopting an overall healthy lifestyle (normal weight, not smoking, regular physical activity, moderate alcohol consumption, and a good diet including sodium reduction) has been shown to be associated with blood pressure approximately 3 mm Hg lower and a 30% reduction in the risk of cardiovascular disease, regardless of the genetic risk. Conversely, an unhealthy lifestyle increases blood pressure and the risk of cardiovascular disease, even in those who are genetically less at risk of hypertension.
In short, taking your blood pressure regularly, even at a young age, can literally save your life. The easiest way to regularly check your blood pressure is to purchase one of the many models of blood pressure monitors available in pharmacies or specialty stores. Take the measurement in a seated position, legs uncrossed and with the arm resting on a table so that the middle of the arm is at the level of the heart. Two measurements in the morning before having breakfast and drinking coffee and two more measurements in the evening before bedtime (wait at least 2 hours after the end of the meal) generally give an accurate picture of blood pressure, which should be below 135/85 mm Hg on average according to Hypertension Canada.