Sunday, August 17, 2008

Acute Stress Does Not Predict PTSD

If you’re trained as a psychologist, these may be fighting words. They call into question the very accuracy of the Diagnostic and Statistical Manual (DSM), otherwise known as the Psychologists’ Bible.

If you’re not a psychologist but happened across this blog because you were expecting me to comment on Nadal and Federer both winning gold in Beijing, sorry to disappoint you. Honestly, I think that Juan Del Potro of Argentina winning four straight tournaments is the far more intriguing story. I hope Del Potro has some energy left for Flushing Meadows. I’d hate to see him fizzle out aft
er the big boys return stateside.

But right now I have posttraumatic stress disorder (PTSD) on the mind because I have been preoccupied by the conflict in Georgia and by whether our already overtaxed military is going to have to get involved there. And what are the implications for world peace if two of the greatest superpowers do not succeed in finding a path towards peace through the powers of diplomacy? Really, can our service members take any more?

You see I am preoccupied by this because I know that a huge proportion of the soldiers returning from Afghanistan and Iraq come back with symptoms of PTSD and traumatic brain injury [TBI]. The last thing they need is another conflict with exposure to even more combat stress. Dealing with terrorists who remain indistinguishable from everyday Afghans and Iraqis is hard enough on the psyche. Having to get involved in a conflict that represents a throwback to t
he era of George Smiley could push some over the edge.

This is the background preoccupation that continues like white noise as I read the results of a recent study conducted by a team of Australian researchers who found that there is no predictive link between ASD and PTSD. And so that I can explain to you why these may be fighting words, let me spend a minute defining each of these acronyms.

According to the current version of the DSM, a diagnosis of Acute Stress Disorder (ASD) is appropriate when an individual experiences a traumatic event that triggers symptoms similar to PTSD, but only if symptoms endure between two days and four weeks. If symptoms persist beyond a month, the individual then meets the criteria for a PTSD diagnosis. The essential difference between PTSD and ASD then is a matter of duration.

It is accepted as fact among most psychologists that people who develop ASD are at greater risk of developing PTSD. This assumes a natural progression between the disorders, and implies that one should be able to predict the latter from the existence of the former. In other words, while some individuals may recover from traumatic stress and may not go on to develop PTSD, one cannot develop PTSD without first going through a precursor phase of ASD.

Well, it turns out that it is not entirely true. Results of a large study conducted by Richard Bryant, Ph.D. and his team of researchers at the University of New South Wales, have concluded that there is actually little predictive link between ASD and PTSD.

Bryant and his group studied 500 civilians who were admitted to four major trauma hospitals across Australia between April 2004 and April 2005. The causes of trauma ranged from injury due to a motor-vehicle accident [62%], a fall [16%], an industrial accident [8%], assault [5%], and a cluster of other reasons [9%]. Within one month of hospitalization, 33 individuals (or 6%) met criteria for a diagnosis of ASD. Three months later, only forty-nine individuals (or 10 % of the sample) met the criteria for PTSD. The researchers then examined how many of the 49 PTSD patients had been previously diagnosed with ASD. Turns out only 15 of them had. This translated to a 31 percent predictive value. In other words, 69% of the patients who were eventually diagnosed with PTSD were not initially assessed as having ASD.

There was however, one category of patient for whom ASD held better predictive value – and these were patients who had also experienced a brain injury. ASD predicted PTSD for 58 percent of the sub-group of subjects diagnosed with both PTSD and TBI.

This is the finding that got me thinking about the conflict in Georgia and its implications for service members for whom TBI has already been identified as the signature injury of the two existing conflicts in the Middle East. Really, most of them just cannot take any more.