Treating blood pressure to prevent strokes: The age factor.

The importance of systolic blood pressure (SBP), diastolic blood pressure (DBP), and pulse pressure (PP), on the incidence of coronary heart disease (CHD) and stroke are known. However, the importance of blood pressure (BP)-age shifts regarding the stroke incidence is not clearly known. The BP changes with the advancement of age from the predominance of DBP in the young to the predominance of SBP in the old. This change is due to the stiffening of the large arteries as a result of the aging process and the replacement of the elastic fibers with collagen fibers. This change results in the loss of compliance and the elastic recoil of these vessels leading to increase in pulse wave velocity, central SBP and widening of pulse pressure leading to an increased incidence of CHD and strokes. It has been demonstrated epidemiologically that the SBP rises linearly with age, whereas the DBP rises up to the age of 45-50 years, and then begins to decline after the age of 60 years leading to a progressive widening of PP. Several studies have shown an inverse relationship between DBP and CHD, whereas no such relationship has been demonstrated for stroke. However, a recent study showed an inverse relationship with DBP and stroke when it dropped below 71 mmHg in subjects 50 years of age or older. In contrast, there was a positive association between BP and stroke when both SBP and DBP were ≥ 71 mmHg. These findings suggest that in treating systolic hypertension in the elderly to reduce stroke risk, attention should be paid on the potential harm of low DBP and the widening of PP regarding CHD and stroke. The implications of BP shifts with age and the potential risks of low DBP regarding the risk of stroke will be discussed in this concise review.