http://www.economist.com/news/science-and-technology/21639438-controversial-trial-mysterious-disease-continues-yield-insights-fear?fsrc=scn/tw_ec/fear_to_tread Fear to tread A controversial trial on a mysterious disease continues to yield insights Jan 17th 2015 | From the print edition CHRONIC fatigue syndrome (CFS) is an illness that robs its victims of concentration, sleep and—as the name suggests—energy. What causes it is a puzzle. Hypotheses include it being the long-term consequence of viral infection, some sort of autoimmune reaction, or a species of depression. Some researchers argue that it is actually a spectrum of diseases; others say this view risks making it a dumping ground for not-otherwise-specified illnesses with similar symptoms. Even the name raises hackles among patient and advocacy groups, who suggest it sounds as if those who have it are lazy or just need a good nap. These days, CFS often appears in conjunction with the term myalgic encephalomyelitis, a decidedly more medical-sounding designation which gives the impression that a cause has been hunted down and named. It has not. The duality of names reflects an ideological rift regarding whether CFS’s causes are physiological or psychological. Among patients and advocacy groups, there is long-running resentment of the idea that the disorder is “all in the mind”. And no single study tore that rift open more widely than a paper published in the Lancet in 2011, the results of which have been followed up this week by a second paper in Lancet Psychiatry. The PACE trial, on which the original paper was based, was the largest of its kind. It followed 641 participants over the course of a year. It was designed to compare the effects of a few well-established treatments. These included graded exercise therapy (GET), in which patients gradually increase the length or intensity of a set of exercises; adaptive pacing therapy (APT), a strategy to set modest exercise goals but to stay within an maximum “envelope” of exertion defined by the illness; and cognitive behavioural therapy (CBT), which aims to identify and adjust the thought processes that lead to unhelpful behaviours. When the numbers were crunched, both CBT and GET were shown to improve outcomes, such as self-reported levels of fatigue and physical fitness. APT, on the other hand, was not. The findings sparked a furious and public debate between the researchers, the editors of the Lancet, advocacy groups and some patients, who called the study’s methods and conclusions into question. At issue was the quantity of resources spent looking at effects in patients’ psyches rather than hunting for more tangible causes and effects in their bodies. Many researchers studying psychological or psychiatric causes of or treatments for CFS reported being harassed in person and online. Some received death threats. Undaunted, several of the paper’s authors have spent the intervening time using a technique called mediation analysis to tease out the reasons why CBT and GET had their positive effects. Mediation analysis turns questions of cause and effect into mathematical equations, presuming that a positive clinical outcome after a particular treatment occurs because of one or more “mediators” in between. The team examined the responses to a detailed questionnaire administered part-way through the trial. Questions had been designed to measure established psychological factors that might serve to mediate the various treatments; for example, whether a respondent agreed with the statement, “I am afraid that I will make my symptoms worse if I exercise” fell into the category of fear avoidance. Other categories included avoiding embarrassment, focusing on symptoms (thinking frequently about the illness and its effects) and catastrophising (believing things were worse than they really were). In each case, the analysis puts the category into the equation and determines if its presence looks statistically likely to have made a difference to the outcome. The results, which are the subject of the new paper, show one of the main ways CBT and GET trumped APT was that people prescribed them were less fearful than those prescribed APT. This seemed to account for about 60% of the advantage they brought. GET also brought an increase in tolerance to exercise that APT, with its concern not to overstep the boundaries, did not. One psychological mechanism, then, and one physiological one. That both are involved is hardly surprising. The link between a healthy mind and a healthy body (and vice versa) has been known since classical times. That, though, is by no means the same as saying something is all in the mind. --------------------------------- You can leave comments.