So is high blood pressure really genetic? Yes, hypertension is inherited, but this does not automatically mean that you will develop it yourself if most of your family members have it. However, it is not yet known exactly how it is inherited. Some characteristics and some rare diseases can be caused by inheriting single genes. But it is also known, with certain rare exceptions, that high blood pressure is hardly ever inherited in this simple way.
In most cases, high blood pressure depends on the interaction of various inheritable factors, which may only become activated only in the presence of certain environmental conditions. This is known as genotype-environment interaction. The most important of these conditions is probably prematurity, obesity in adolescence and as a young adult, sodium intake and alcohol intake particularly in early adulthood. In any case, however, it is pointless to argue about nature versus nurture, or environment versus inheritance. It is more essential to acknowledge that there may be a possibility pf developing high blood pressure and that one should be sensible about what one eats and drinks and the amount of exercise that one does.
High blood pressure may begin in childhood. Nevertheless, knowing this is of little practical use. There is already evidence that weight control in case of childhood obesity, perhaps on a vegetarian diet, may be a good prophylactic against later high blood pressure in adulthood, but not much data to support any other specific preventive actions. Generally, screening children for blood pressure is essentially a method of research, not a useful procedure in general practice and, if done at all, it must be done by highly trained medical personnel. The fact that high blood pressure begins with inheritance or in childhood does not mean that you actually had high blood pressure in childhood – just that the tendency for you to develop it as you grow older is already there. Screening is not useful for finding the equally rare cases of secondary high blood pressure, where blood pressure rises rapidly over a short period and is caused by some other illness, which is usually a kidney disorder. Knowing that a child has high blood pressure is not a very useful predictor of what will happen as the child ages. Although there is a general tendency for newborns with high blood pressure to become adults with hypertension, the association remains debatable. In a study of fourteen year olds with untreated high blood pressure (170/100 mmHg) examined twenty years after, only 17% had hypertension twenty years later.
The causes of high blood pressure in people in their 30s are generally the same as in those individuals who are older, regardless of smoking and drinking behavior. In such cases, it should be noted that most causes of high blood pressure in middle age and later life are still uncertain. The main difference is that in younger adults, there are more cases of secondary high blood pressure caused by other conditions, often those disorders involving the kidney and the adrenal glands. Everyone aged under 40 found to have high blood pressure should be referred to a consultant for individual examinations to see if it is being caused by such conditions. For the occasional person with very high blood pressure (sustained diastolic pressure of 120 mmHg or more), physicians should still monitor these individuals closely. For most people in this age bracket with raised blood pressure but below this level, routine referral for these medical examinations is not necessary – providing that the physician organizes a few simple tests and make a careful evaluation of responses to treatment. Most people who then need a medical specialist, not just for routine tests but a comprehensive and detailed search for the causes of raised blood pressure, can then usually be identified so that these individuals can get the attention they deserve, as many of these underlying causes are very difficult to find.
