Map of life expectancy at birth from Global Education Project.

Thursday, March 22, 2007

Why can't you behave yourself?

As Roger points out, there are many ways in which we slowly kill ourselves besides not taking our meds. People in the public health biz are obssessed with how to get people to act in ways that are good for them -- at least as defined by the public healthologists -- and perpetually frustrated that they don't. Smoking, eating junk food, couch potatoing, getting fat, chugging Old Overjolt out of the bottle, injecting heroin into your veins, driving without a seat belt, sleeping only 6 hours a night, crossing against the light -- why do you do these things you idiot?

In order to get funding for a study or an intervention, you need to articulate a behavioral theory on which your project will be based. These theories are incredibly banal ideas tarted up in fancy dress -- with names like the Health Beliefs Model, Theory of Reasoned Action, Social Learning Theory, and the powerhouse Transtheoretical Model, also known as Stages of Change.

The Health Beliefs Model is more or less how your doctor is supposed to think. You make a so-called "rational" analysis comparing the risks of taking (or not taking) an action, the alternatives, the benefits, and do the math. Let's see, if I don't take the pills I'll have a reduction in life expectancy of 4.6 months, with a 20% risk of dying 2 years early, and a 30% chance that it won't make any difference, plus a .05% chance of significant side effects. If I do take the pills it will cost me $450 a year for the next 20 years which if invested in a conservative bond fund in a Roth IRA will be worth $6,000 by the time I'm 64 . . .

Uh, no, we don't really think that way. Social Learning Theory notices that we tend to imitate what other people do, and do what we are taught to do, in other words we start smoking because we aren't even thinking about dying of lung cancer, we start smoking because the cool kids do it. The Theory of Reasoned Action means I get benefits from having unsafe sex, such as I enjoy it or whatever, so maybe I'm not so dumb after all.

You get the idea. When people behave in ways that may harm their health, in the long or short term, they are making choices for which from their point of view they may have perfectly good reasons, even if we older, wiser adult types don't agree with those reasons. Can we really claim that the world will be better off if everybody accepts our idea of what's good for them, instead of their own? One argument in favor of that proposition is that the equation usually looks a lot different to people later on when they find that they actually have lung cancer or HIV or heart disease, and they regret the choices they made earlier. Another argument is that the rest of us have to take care of them. And, if we invest in efforts to persuade them or motivate them to make healthier choices, those will still be their choices, after all -- we aren't forcing them, we're just looking for ways to rebalance their Social Learning and their Reasoned Action.

But, it turns out to be very difficult. Community interventions to influence health related behaviors often have some effect, but usually small and not a lot of bang for the buck. One exception in the U.S. has been tobacco control -- the prevalence of smoking has gone down steadily for the past 20 years, although it has accelerated considerably with the introduction of coercive measures such as workplace smoking bans and effective efforts to prevent youth from buying tobacco. So far, we're getting nowhere fast with diet, physical activity, and obesity. But maybe we will figure out better ways in the years ahead.

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