4 December 2007
Biological Cause For Body Dysmorphic Disorder?
by Kate Melville
A new imaging project from UCLA reveals that the brains of people with body dysmorphic disorder (BDD) look normal, but function abnormally when processing visual details.
People who suffer from BDD perceive themselves as ugly and disfigured. Individuals with BDD often fixate on an imagined flaw in appearance or a slight physical abnormality. To fix their "problem," they tend to pursue plastic surgery - sometimes repeatedly. They often feel ashamed, depressed and anxious, increasing their risk of suicide. Affecting an estimated two percent of the population, BDD tends to run in families and is especially common in persons with obsessive-compulsive disorder.
Writing in the Archives of General Psychiatry, UCLA's Dr. Jamie Feusner said that it appeared that while the brain's "hardware" in BDD sufferers worked fine, there was "a glitch in the operating software that prevented patients from seeing themselves as others do." Feusner's conclusion is based on functional magnetic resonance imaging (fMRI) that revealed how the patients' brains processed visual input.
Feusner outfitted 12 BDD patients with special goggles that enabled them to view digital photos of various faces as they underwent a brain scan. Each volunteer viewed three types of images. The first type was an untouched photo. The second type was a photo altered to eliminate facial details that appear frequently, such as freckles, wrinkles and scars. This "low frequency" technique blurred the final image.
The third type of image essentially subtracted the blurred second image from the untouched photo. This "high frequency" technique resulted in a finely detailed line drawing. Feusner's team compared the BDD patients' responses to 12 control subjects matched by age, gender, education and handedness. What the scientists observed surprised them.
"We saw a clear difference in how the right and left sides of the brain worked in people with BDD versus those without the disorder," noted Feusner. BDD patients more often used their brain's left side - the analytic side attuned to complex detail - even when processing the less intricate, low-frequency images. In contrast, the left sides of the control subjects' brains activated only to interpret the more detailed high-frequency information. Their brains processed the untouched and low-frequency images on the right side, which is geared toward seeing things in their entirety.
"We don't know why BDD patients analyze all faces as if they are high frequency," said Feusner. "The findings suggest that BDD brains are programmed to extract details - or fill them in where they don't exist. It's possible they are thinking of their own face even when they are looking at others."
Feusner also recently discovered that the more severe the BDD patient's symptoms, the more strongly the brain's left side activates during visual processing. He is currently studying how BDD patients process their own faces in order to explore how emotional arousal may influence visual processing. "All of these findings indicate that BDD has a biological link and can no longer be attributed solely to our society's focus on appearance," he concluded.
Source: University of California - Los Angeles