Anorexia leads to emphysema-like disease
October 12, 2004
By Karla Gale
NEW YORK (Reuters Health) - Anorexia nervosa causes a loss of lung tissue, resulting in changes that resemble emphysema, according to a new report.
"One of the problems with emphysema is that it is a complicated disease, and no one knows how it starts -- why so many people can smoke but only a small percentage get emphysema," lead author Dr. Harvey O. Coxson said in an interview with Reuters Health.
He believes that the findings in people with anorexia will help uncover the underlying cause of emphysema.
Emphysema was first observed as a consequence of chronic malnutrition in the Warsaw ghetto during World War II, Coxson and his colleagues point out in the October 1st American Journal of Respiratory and Critical Care Medicine.
His group previously reported that lung density, as measured by computed tomography, in people with anorexia is related to their weight.
For their current report, Coxson, a radiologist at Vancouver General Hospital in British Columbia, and his team examined 21 people suffering from anorexia for 1 to 36 years, and compared them with 16 "control" subjects without any eating disorder.
Seven of the anorexics weighed less than the World Health Organization's cut-off for starvation.
The average lung density was significantly lower in the anorexic group than the control group, and the surface area of lung tissue in contact with air was halved. However, pulmonary function was similar between the groups.
"These people are relatively young, so they don't have any pulmonary function abnormalities yet," Coxson said. "The lung has a huge reserve, which may be why (emphysema) seems to not strike until the mid to late 60s. The emphysema could have been going on for a long time before that."
The process his group saw might actually be a survival mechanism, he added. "Because the body is being malnourished, it can't use as much oxygen but it does need the nutrients, so it is lowering lung tissue content, recycling it within the body."
These findings fit in with previous observations that patients with emphysema tend to be more malnourished than people with chronic bronchitis, he said. "But we don't know if they are malnourished because they have emphysema, or if they're malnourished and that drives the emphysema process."
The next phase of their study should help answer that question.
It has been 2 years since the participants' lungs were examined by CT, Coxson said. "Now we're bringing them back to look at their lungs again and compare it to any change in nutritional status."
As he explained, "Our hypothesis is that if their nutritional status has improved, there will be improvements in lung structure, and if the nutritional status has deteriorated, then the lung will also have gotten worse as well."
SOURCE: American Journal of Respiratory and Critical Care Medicine, October 1, 2004.