updated 5/27/2010 11:05:26 AM ET 2010-05-27T15:05:26

Anorexics who lose excessive weight can also see a shrinking in the brain's gray matter. But new research suggests when they reach a healthy body size they also pack on the gray matter volume.

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The eating disorder officially known as anorexia nervosa, in which an individual starves him or herself or binges and purges, can lead to all sorts of problems as the person becomes malnourished.

"Anorexia nervosa wreaks havoc on many different parts of the body, including the brain," said study team leader Christina Roberto of Yale University.

Past research has shown that anorexics who had maintained a healthy body weight for at least a year didn't show significant differences in brain volume compared with their counterparts without an eating disorder, suggesting any neural deficits had been rectified. But how fast the matter returns and how this happens over time were not known.

Starving brain tissue

To find out, Roberto and her colleagues used magnetic resonance imaging (MRI) to take pictures of the brains of 32 adult female patients with anorexia nervosaand 21 healthy women without any psychiatric illnesses.

The anorexic participants were split between two subtypes: those who restrict caloriesand those who binge eat and purge.

The patients, who were between the ages of 18 and 45, got brain scans prior to their inpatient weight-gain treatment at the Columbia University Center for Eating Disorders and again once they had reached 90 percent of the ideal body weight.  

During treatment, they had to meet certain goals each week in terms of weight gain, and they had to eat 100-percent of their food.

When in a state of starvation, the women with anorexia nervosa had less gray-matterbrain volume compared with healthy women. And those who had the illness the longest showed the greatest reductions in brain volume when underweight.

The average gray-matter volume of anorexics was about 648 milliliters initially, compared with about 680 ml for healthy individuals. While the gray-matter volume stayed constant for healthy participants, it increased to an average of 663 for anorexics at their second scan (when they'd reached the weight benchmark).

"Within a few weeks a little over a month we started to see that reversal. Their gray matter didn't fully normalize, but another study suggests if a patient maintains that weight over time it probably will fully normalize."

White matter another matter

The scans didn't show significant changes in white-matter brain volume. (While gray matter is mostly found on the brain's surface, called the cortex, where brain cells are packed, white matter is buried deep in the brain and is made up primarily of long, spindly appendages of some brain cells.)

Though anorexia nervosa tends to lead to a decrease in brain volume, Roberto said researchers aren't exactly sure why. "We hypothesize that it's linked to starvation and being in an underweight state. If you starve yourself, that nutrition deficit leads to reduced brain volume," Roberto told LiveScience.

Scientists aren't sure whether or not the brain-volume changes have an impact on cognition, and that's something Roberto would like to look into. There have been reports of cognitive impairment in those with anorexia nervosa, but scientists don't know if it's linked to grey-matter shrinking.

In terms of full recovery from the disorder, Roberto said overall about one-third of sufferers get better fully, one-third struggle over time, and one-third remain chronically ill. 

The results are detailed in the May issue of the International Journal of Eating Disorders.

© 2012 LiveScience.com. All rights reserved.

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