Compensation is not a Cure: an Example Involving Blood Pressure

Near the entire corpus of present day medicine for age-related disease, even the comparatively successful treatments, is essentially compensatory in nature. It fails to address in any meaningful way the underlying causes of aging and disease. "Comparatively successful" is presently measured against doing nothing, rather than against the goal of a cure, of controlling the aging process. By that latter standard, there is no such thing as successful medicine for age-related disease. Yet.

The research noted here is one small demonstration of the point that compensatory efforts fail because they do not address the root causes of the problem: the underlying pathology marches on, overwhelms the bounds of possible compensatory efforts, and patients decline and die as a result. Blood pressure rises with age because blood vessels stiffen, because of persistent cross-links in the extracellular matrix, and because of calcification encouraged by the presence of senescent cells, and because of related dysfunctions in the signaling mechanisms that coordinate vascular contractions and reactions to pressure. Current pharmaceuticals that do reliably lower blood pressure do nothing for the roots of the issue.

Hypertension affects about 40% of those aged over 25 and is a major risk factor for heart disease, stroke and kidney failure. An interdisciplinary group of scientists found that conventional medication aimed at reducing high blood pressure restored normal vascular rhythms only in the largest blood vessels but not the smallest ones. "It is clear that current anti-hypertensive treatments, while successfully controlling blood pressure, do not restore microvascular function."

Based on a networks physiology approach, the researchers compared a group aged in their twenties and two older groups aged around 70 - one with no history of hypertension and the other taking medications for high blood pressure. In the older group being treated for high blood pressure the drug treatment restored normal function at the level of arterioles and larger vessels. But when the researchers studied the nonlinear dynamical properties of the smallest blood vessels in the body, they found differences between the two older groups.

"Specifically, current hypertensive treatment did not fully restore the coherence or the strength of coupling between oscillations in the heart rate, respiration, and vascular rhythms (vasomotion). These are thought to be important in the efficient and adaptive behaviour of the cardiovascular system. Indeed, one aspect of ageing is the progressive physiological weakening of these links that keep the cardiovascular system reactive and functional. The results have not only confirmed previous observations of progressive impairment with age of the underlying mechanisms of coordination between cardiac and microvascular activity, but for the first time have revealed that these effects are exacerbated in hypertension. Current antihypertensive treatment is evidently unable to correct this dysfunction."



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