Recounting PTSD diagnoses
If you needed any evidence to understand the political side of mental illness look no farther than the latest issue of the journal Science (vol 313, no 5789, pp 979-982) in which an article titled, "The Psychological Risks of Vietnam for U.S. Veterans: A Revisit with New Data and Methods" has been published. This article describes a recent study designed to reexamine a previous study, the National Vietnam Veterans Readjustment Study (or NVVRS), originally published in 1989, which has been accused of providing an overly inflated estimate of the occurance of PTSD in Vietnam Veterans. Working from the original sample materials plus additional materials drawn from military records, the new researchers came to different conclusions than their predecessors. It seems that the actual incidence of PTSD was significantly lower than originally estimated. Where the original NVVRS found that 31% of returning vets had PTSD at some point in their lives, and 15% were currently dealing with PTSD, the new authors have concluded that only 19% of the returning vets ever had PTSD, and that only 9% of them had PTSD just over a decade after the war, in 1989. The same basic set of information is examined, but now different results are yielded. How is that possible?
The thing is, data is never easy to interpret. It is just a bunch of numbers upon which statistical analyses are run. It is up to human beings making decisions (sometimes arbitrary decisions) to interpret data. One sort of arbitrary decision that gets made from time to time is how tightly or loosely to define a group of individuals. The way diagnostic criteria (such as appear in the DSM) are written, you either have a disorder or you don't. If you meet five out of seven criteria necessary for the diagnosis of PTSD (however many there are), well, then you can be said to have PTSD. The thing is, however, that the entire criteria set is some what arbitrary in nature. It's not that a bunch of doctors got together and make up disorders like PTSD out of their imaginations. Quite the contrary, PTSD does have an independent existance. There is nothing binary about PTSD in the real world, however. Like most other natural things, PTSD is a continuous sort of thing - you can have a little of it, or a lot of it or any amount in between. Just becuase the DSM says that a minimum number of criteria must be met before a disorder is present doesn't mean that people aren't suffering if they meet some of those criteria but not all of them.
I suspect that what has happened with the recent reanalysis of the orignal NVVRS data (as augmented by the new military data) is that definition of what constitutes PTSD has been applied somewhat more strenuously than in the original study. The experiences the soldiers went through have not changed, but becuase the data are being held to a higher standard, there appear to be fewer people who are worthy of the sick lable. That's arbitrary of course. The number of people who were suffering in 1989 has not changed. The only thing that has changed is how the suffering is measured and labeled. The new authors are saying that some of the people who used to wear the label "PTSD" no longer merit it. Truthfully, I'm not sure if that is a good thing or a bad thing.