Friday, December 21, 2007
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Anorexia ‘cannot be picked up by looking at photographs of super-thin models’
Anorexia may be caused by inherited differences in the way a sufferer’s brain operates, leading to obsessive behaviour, according to research.
Rather than being triggered by images of super-thin models and celebrities, the eating disorder could be brought on by the in-built way in which the brain responds to pleasure and reward. It has been argued that images of unhealthily thin stars in the media have encouraged anorexic behaviour in impressionable young women. But a study published in The American Journal of Psychiatry suggests that the brains of anorexia sufferers behave differently to those of the rest of the population and that certain people are born with a susceptibility to develop the condition.
A team of psychiatrists, led by Walter Kaye, of the University of Pittsburgh, tested the emotional responses of 13 former anorexics compared with those of 13 nonsufferers.
The women were asked to play a computer game where correct guesses were rewarded financially. During the test, the team used functional MRI scans to monitor the participants’ brain activity by measuring blood levels in certain areas.
Among the nonsufferers, the brain region connected to emotional responses – the anterior ventral striatum – showed strong differences between winning and losing the game. Among the women with a history of anorexia, however, there was little difference in activity between winning and losing.
Professor Kaye said: “In anorexia, this might impact on food enjoyment. For anorexics, then, perhaps it is difficult to appreciate immediate pleasure if it does not feel much different from a negative experience.”
Another brain area, the caudate, involved in linking actions to outcome and planning, was far more active in the recovering anorexics than in the control group. The former tended to have exaggerated worries about the consequences of their behaviours, looked for rules where there were none and were overly concerned about making mistakes.
“There are some positive aspects to this kind of temperament. Paying attention to detail and making sure things are done as correctly as possible are constructive traits in careers such as medicine or engineering,” Professor Kaye said. “But carried to extremes, such obsessive thinking can be harmful, which is what happens in anorexia. This piece of research points to the fact that the brains of people with anorexia are wired differently.
“This means they react and think in different ways to the ordinary person and that they are more likely to go on to develop anorexia regardless of whether they have been exposed to images of super-thin models.”
Professor Kaye said that his study showed that even former anorexics still had difficulty enjoying simple pleasures. “What this points to is that anorexics have something different going on in their brains, which marks them out as having either different structures in the brain or different pathways for processing thought that stay with them for life. We may be able, with a lot of hard work, to get them back to eating, but deep down in their brain there appear to be biological differences that don’t go away.”
Ian Frampton, a psychologist at Exeter University, has been working with anorexics using the same MRI technology. He said: “Professor Kaye’s research supports a growing feeling that anorexia is a biological condition caused by the brains of some people being structured in a different way. We are still conducting our research, but we are seeing similar things.
“We are not totally sure what is happening in these youngsters but we think that some of this might be inherited or some might be due to a fault in the developing brain either in the womb or during early childhood.”
Dr Frampton said that while all adolescent girls have issues about body image, for most it is a passing phase: “We need to move away from this idea that supermodels are to blame. It is probably not good for them to look as they do. But for anorexics, the desire not to eat and to be thin seems to be already in them and not something they can pick up by looking at a magazine.
“There were, after all, anorexics before super-thin models.”
Possible triggers
–– Recognition of anorexia nervosa dates from work in London and Paris in 1873, but a disorder apparently resembling it was first written about by John Reynolds, a physician and minister, in 1669
–– Beat, the eating disorders charity, says that a disorder is unlikely to result from a single cause. Potential triggers include low self-esteem, problems with friends or family relationships, the death of someone special, problems at work or university, sexual or emotional abuse
–– The most likely group to be affected are young women, especially those aged 15 to 25
–– About 90,000 people in Britain are estimated to be receiving treatment
–– The effects of anorexia, other than weight loss, can include constipation, dizzy spells, bloated stomach, downy hair on the body, poor blood circulation, loss of periods, loss of interest in sex and loss of bone mass, eventually leading to osteoporosishttp://www.timesonline.co.uk/tol/life_and_style/health/article3060191.ece
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