Hardly a day goes by but what I see is a headline that attributes some spurious correlation with better health, wellness, and longevity. A new study from Kentucky found that the addition of trees – yes, trees – lowers inflammation and reduces heart disease.
The University of Louisville’s Green Heart Louisville Project has found that people living in neighborhoods where the number of trees and shrubs was more than doubled showed lower levels of a blood marker of inflammation than those living outside the planted areas. General inflammation is an important risk indicator for heart disease and other chronic diseases.
It is interesting research, but I doubt if the trees themselves boost heart health. There is something not being measured that is correlated with trees and better health. One of the most common associations that I see involves variables that are deemed to improve health and longevity but were really proxies or indicators of wealth. A 2021 retrospective study summarized by Harvard Medical School found:
“Decreases in wealth are associated with more stress, fewer healthy behaviors, and less leisure time, all of which are associated with poorer cardiovascular health,” said Andrew Sumarsono at the University of Texas Southwestern’s Division of Hospital Medicine. “It is possible that the inverse is true and may help to explain our study’s findings.” “Wealth and health are so closely integrated that we can no longer consider them apart,” said Vaduganathan. “In future investigations, we need to make dedicated efforts to routinely measure wealth and consider it a key determinant of cardiovascular health.”
If wealth boosts health, wouldn’t lottery winners be super healthy? I suspect the opposite is true. Education is also correlated with better health, but also with wealth. Does going to college for four years somehow boost health? Or do healthy people go to college? Married men and women are healthier than their unmarried peers living about two years longer than those who are unmarried. Why is this? One theory posits that women police their husband’s behavior and influence healthier habits. Another theory is that healthier people are more likely to get married in the first place. Finally, two people joining their lives and finances are wealthier than those who remain single. In any case, marriage is a proxy for other things, not the cause itself.
Psychology Today wrote about health and social status. Using animal models as examples, researchers suggest there could be a genetic component. Perhaps both health and wealth are the results of good genetics:
This theory is supported by evidence that longevity is mildly heritable. Presumably those who lead very long lives enjoy unusually good health reflecting a robust immune system and other traits that favor survival, including optimism. Genes can account for approximately one-fifth of variability in longevity.
It is common in health policy to attribute better health and longevity to better medical care, or conversely the lack of a socialized medical system of universal coverage. The Lown Institute looked at utilization of high-value and low-value medical care by income. The rich get more high value care but also more low value care, concluding.
The fact that rich patients were more likely to receive every type of high-value care measured reflects issues of access in our health system. We need universal coverage with low or no cost sharing so that preventive care is truly affordable for all. On the overuse side, there’s still a lot we don’t know about what causes different rates of low-value services by income.
Yet, the volume of care and cost of medical care with health status is a spurious relationship at best. A study of both English and American adults found that the wealthy not only enjoy longer life, but years of disability free life compared to poorer counterparts.
According to a new study, wealthy men and women don’t only live longer, they also get eight to nine more healthy years after 50 than the poorest individuals in the United States and in England.“It was surprising to find that the inequalities are exactly the same,” said Paola Zaninotto, a professor of epidemiology and public health at University College London and a lead author of the study.
The British National Health Service provides care that is subsidized with taxes and mostly free or low cost at the point of service. It is a system that advocates would love to see in the United States. Despite the availability of low-cost care, the poor still have poorer health.
A popular phrase in public health is “social determinants of health”. A multitude of things supposedly reduces health status. These include income, education, occupation, employment, where you live, housing, early childhood, family structure and social inclusiveness. It is unlikely that any of the above actually influences health. Rather, they are correlated in ways that medical science has yet to be uncovered.