… A formal assessment of the American diplomats’ health commissioned by the US government was published in March by doctors at the University of Pennsylvania. The preliminary report in the Journal of the American Medical Association describes a new syndrome that resembles persistent concussion in people who have not received blows to the head.
But in a letter published in the Journal of Neurology, Sergio Della Sala and Robert McIntosh, both neuroscientists at the University of Edinburgh, claim the US report is seriously flawed.
Della Sala said much of the evidence the doctors used to propose a new concussion-like syndrome came from six diplomats who each took 37 cognitive tests. The tests looked at visual and auditory attention, working memory, language, reasoning, movement and other cognitive abilities.
In their report, the US doctors reveal that all six embassy staff who had the full battery of tests had some brain impairment or another. But Della Sala and McIntosh say anybody who took the tests would have been classed as impaired.
They point out that it is standard practice with cognitive tests to measure people’s performance against others in the population. Often, a person has to score in the bottom 5% to be considered impaired. But the US doctors set the threshold at 40%, meaning that by definition, four in 10 who take the test will be “impaired”.
Della Sala and McIntosh ran a simulation that looked at the probability of passing all 37 tests when the threshold for failure was set so high. “The chances that somebody will be without an impairment is zero,” Della Sala said. “We ran the simulation 1,000 times, and never, ever is there one single individual who appears to be normal. They are all classed as impaired.”
He added: “I’m not denying that they may have discovered a new syndrome, but the point is that the evidence they have provided is nonscientific. The paper is faulty. Even if the results are preliminary, a threshold that verges on half the population is unheard of. I cannot see how any reviewer could have looked at the data and said they are fine. This is not a little thing. It is a threshold unknown in science or clinical practice.”…