Getting What We Deserve: Health and Medical Care in America

4. THE COMPLEX NATURE OF CAUSALITY

32 6 6 6 4 The Complex Nature of Causality Disease and health are the outcome of complex, intersecting influences. Genes might vary the risk of lung cancer among smokers , but if you don’t smoke, it is far less likely that you will get lung cancer. That’s pretty straightforward. Other chains of causality are not. We are experiencing global epidemics of asthma, diabetes, and heart disease. People have not changed their genes; what they’ve changed, broadly speaking, is their “environment”: what they eat, what they drink, what they breathe, how they have sex, where they work—and with whom. Increased air pollution and more exposure to household dust and mites have raised the global risk of asthma. Jim Anthony, a professor of mental health at Johns Hopkins, has shown that asthma leads to“panic attacks.”His colleague Bill Eaton has shown that panic attacks increase the risk of suicide. Finding proof mightbe difficult,butitseems reasonable to conclude thatair pollution increases the number of suicides! The Complex Nature of Causality 33 As for the “chaotic complexity of whole body biology,” Matt Ridley points out in Genome that “stress” (as brought on, perhaps, by taking the college board exams) causes a whole cascade of physiological events, including increased levels of circulating cortisol, which influences the activity of the TFG gene on chromosome 10, suppressing the expression of interleukin 2 and thereby increasing the risk of infection.1 Hence, taking an examination might indeed make you ill (something students have long claimed)! Psychic Stressors Some powerful determinants of health work through subtle psychological mechanisms. Michael Marmot, a respected English epidemiologist , provided one of the earliest and best illustrations of the “social gradient of disease.” In his famous Whitehall Study, he followed the lives of London-based bureaucrats (who worked at Whitehall). He divided them into four social classes: the “born-tolead ” class (my terminology), scions of the upper classes who attended the “right” schools; the “professional and executive” class, who, being technocrats, were probably at least as well educated as the “born-to-lead” class (and perhaps more so); the clerical class; and“others.”All were reasonably well paid by British standards, and all had the same access to the National Health Service. What Marmot discovered should jolt anyone unfamiliar with his results: over the first ten years of follow-up, the“born-to-lead”class was the least likely to die, the professional and executive class had the next lowest death rate, and so forth. The differences were not trivial: the (well-educated) professional and executive class died at almost twice the rate of those “born to lead”; “others”died at more than three times the rate (Figure 10). In addition to differences in smoking, drinking, exercise, etc., there is something about one’s class or standing in the social (pecking) order that dramatically affects health and survival. We don’t yet know what it is; some have 34 Getting WhatWe Deserve made a claim for self-efficacy (the ability to regulate one’s own time and work), but we don’t really know. Whatever the mechanism, it is unlikely to represent a new class of microbes or genes, but its influence seems to be no less determinate. Our “Environment” It is widely accepted that our health (and a lot else about us) is determined by the interaction of our genes with our environment. But what is meant by environment? For a simple-minded person like me, it represents the constellation of factors that surround us (and our genes) and the medium by which they are transmitted (in the broadest terms,“infect”us). For example, the environment contains 20 15 10 5 0 10 Year mortlaity (%) Cause of death All causes Other causes Heart disease Admin. Prof./ Exec. Clerical Position Other Age Adjusted Mortality Rates Whitehall Study Figure 10. Class status determines mortality. Mortality rate among individuals working in the British bureaucracy, London. Over ten years of follow-up, those in the higher social classes died at lower rates than those “beneath”them. This was true for both cardiovascular and noncardiovascular causes of death. Source: Reprinted by permission from M. G. Marmot,“Social Differentials in Health between Populations,”Daedalus 123 (1994): 202. The Complex Nature of Causality 35 germs that are harmful to our health. They may be transmitted and infect us through the air we breathe, the food we eat, the water we drink, or by...