Rolling Down that Old Dementia Highway (January 7, 2017)
Even if you generally avoid health-related headlines (and you should - - the stories behind most of them are piffle), there was one this past week that might have pierced your attitude armor, as it did mine. It announced that a correlation of as great as seven percent had been discovered between the likelihood of developing dementia and living close to a major roadway. For this kind of study, seven percent is a LOT.
But living near a freeway causing dementia? At first, that sounded to me like one of those studies where some desk-jockey researcher and a couple of free interns keep running a bunch of numbers through a computer until a dramatic-sounding (and thus publishable) yet meaningless association shows up. There are more of those “studies” out there than you can shake a stick at. But there are at least two good reasons why this study is a valid one.
The first reason is that the evidence demonstrates that your chances of developing dementia increase progressively the closer you live to a highway. Meaning that the closer you are, the more disease. As you get farther away from the highway, you get progressively less disease, until the effect disappears altogether once you get about a third of a mile from the roadway. Whenever data shows this kind of a linear relationship, you can be almost certain that what you are measuring is a valid risk factor.
Another reason is that people who are into this kind of thing are already mulling over a considerable body of evidence (on the order of thousands of studies) showing that living near busy roads causes similar health problems.You see these problems particularly in children, and because children’s bodies are still developing at the time of this exposure, no matter where they live as adults they will have residual problems. Which problems? Besides dementia, you see an increased incidence of asthma, autism, COPD and death from cardiovascular disease.
What’s the risk factor exactly? Probably mainly (although not exclusively) something referred to as “fine particulate matter”. You know what that is? Air pollution. Hah! Remember air pollution? In the 1950s and 1960s, there were cities (Nashville among them) where the air was sometimes so filthy that people had to put their headlights on in the daytime to drive.
In fact, air pollution was once so bad that the link between lung cancer and smoking was obscured for some time. It took some effort to determine that relationship for sure. Fun fact; at one time Nashville was the city with the most polluted air in the United States! (“We’re number one! Take THAT, Mississippi!”)
You don’t hear much about air pollution these days. It’s one of those problems that is considered by most people to be a thing of the past. Not so -- it is still very much with us. Mostly in poorer communities. Of COURSE in poorer communities, because who is going to live right up against the I-40 or next to a coal plant unless they absolutely have to?
We like to think, and I do include myself in that “we”, that health problems resulting from unhealthy lifestyles can be corrected with a little education and a little more willpower. But in practical terms, they very often can’t be.
It’s true that we spend about ten billion dollars a year on carbonated drinks versus two billion on vegetables, and if we chose to reverse those figures that we’d be better off. And it’s also true that getting out and walking for just ten minutes a day would mean measurable improvement in the lives of millions of people who simply choose not to do so. But some of the nastiest and sneakiest health threats are imposed upon people in places and at times when they don’t really have a choice. That’s true for all of us, but it goes ten times more for poor people, especially poor children.
For example, night shift workers have an increased rate of a number of diseases. If you choose to work those hours because you like to have your days to dress up like a Klingon and go to scifi cons, that’s one thing. (Although I won’t say just what that thing is.) But if this health threat is essentially forced on you because you need the extra job mopping floors in the hospital at night to pay for your kid’s braces, that’s another kettle of fish.
One of the reasons that we fuss as a society about laws regarding air pollution, food labels, toxic exposure and the like is that not everyone has choices about important aspects of their life that affect their health. In the case of the roadways, the pollution causing these problems isn’t visible like it was with the dirty air of olden times. But it's still there and demonstrably causing problems for some of us.
We currently hold the belief, as a society, that we should protect (rather than exploit) the vulnerable among us. This is kind of unusual in human history and everyone I have ever discussed this with says that they share this principle. Apparently it’s the implementation of said principle that is the problem. The devil, as usual, is in the details.
So there we are. Health science endlessly documents problems in the hope that we all will do something about them. Well and good. The better we understand the problems, and as long as we don’t pretend that they don’t exist, we have some hope of solving them. And that is a good thing. Right?
--dr. diane holmes
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