Does anyone know what really causes high blood pressure? It is quite difficult to distinguish whether symptoms stem from high blood pressure or are just mere coincidences. Things are less simple for less obviously absurd cases.
Studies show many different kinds of secondary high blood pressure where the primary causes may be quite different from the continuing causes. An example is a rare disease known as coarctation of the aorta, a disease of the large artery carrying blood out of the heart. In this condition, the aorta is tightly constricted a few inches beyond its origin and then expands to its normal diameter. Undoubtedly, blood pressure must rise above the constriction and fall below it, just as it does when one compresses a hosepipe. Yet, if this constriction is removed surgically and the normal continuity of the aorta is restored, blood pressure usually takes several years to fall to normal level. The initial case of high blood pressure is the constriction, but the continuing cause is probably complex changes in circulating hormones, which function to maintain blood flow through the kidneys despite the obstruction, which may persist for a long time even after the obstruction, has gone.
Aside from the genetic pathogenesis of the disease, there is profound evidence that there are several factors which are true and independent causes of high blood pressure. These factors are obesity, high sodium intake, low potassium intake and a high alcohol intake. The effect they have varies in most cases depending on heredity; they have a much greater effect on people whose families have an increased prevalence of high blood pressure than on people form families with mostly low blood pressure. This will happen sooner in young people and later in middle-aged and elderly people. Evidence of these causes is consistent and convincing. However, that does not eliminate the possibility of other causes present in some people, of which the most obvious and important are psychical, psychological and social stresses.
The theory that physical and psychological stress is the root cause of most high blood pressure was very popular in the 1960s and 1970s, but research since then has proved it not to be true. There may be a minority of people with high blood pressure, for whom it is the main cause, but it fails to explain most cases. Extensive studies have looked for an association between the so-called type A personality (people who are described as ambitious, aggressive and time-conserved) and high blood pressure, but none can be found. Instead, it was found that very nervous people have normal or even low blood pressure but many easygoing people have dangerously high blood pressures. On the other hand, there is a tendency for some people with depression to have raised blood pressures, falling when depression ends, either simultaneously or after treatment for depression. Obviously, there are many other good reasons for avoiding social and psychological stresses, regardless of any ill effects on blood pressure. Even if they are not directly causing high blood pressure, they inevitably affect your capacity to cope with treatment and you should make sure that your physician is aware of them.
Michael Russell
Your Independent guide to Blood Pressure
