UCLA: People with anorexia nervosa and with body dysmorphic disorder have
similar abnormalities in their brains that affect their ability to
process visual information, a new UCLA study reveals. People with anorexia have such an intense fear of gaining weight that
they starve themselves even when they are dangerously thin. Body
dysmorphic disorder is a psychiatric condition characterized by an
obsessive preoccupation with a perceived flaw in physical appearance.
The researchers found that people with both disorders had abnormal
activity in the visual cortex of the brain during the very first
instants when the brain processes “global” information, or images as a
whole, as opposed to a tiny detail. According to the authors, it could
also mean that perceptual retraining may be an effective therapy for
both disorders. Perceptual retraining is a behavioral exercise that
attempts to help adjust or correct the participant’s balance of global
and detailed processing. For both of these disorders, participants are
encouraged to not focus on details and process objects more globally.
Previous research on body dysmorphic disorder has shown the same type
of abnormal activity in the visual cortex, but the UCLA study was the
first to link the locations of the abnormal brain activity with time
periods beginning as early as one-tenth of a second after an image is
viewed. Understanding that timing is significant, the authors write,
because it may help scientists determine whether the problem is in
lower-level perception that takes place in the visual cortex, or
elsewhere in higher-level brain systems.
The study appears in the current online edition of the peer-reviewed journal Psychological Medicine.
The UCLA researchers used functional magnetic resonance imaging, or
fMRI, to detect regional abnormalities in visual processing and
electroencephalography, or EEG, to assess the timeline for how the brain
processes those signals. They compared results for 15 people with
anorexia nervosa, 15 people with body dysmorphic disorder and 15 healthy
individuals.
“We now know that these abnormalities may be happening at the very
early stages when the brain begins processing visual input, and that the
similar distortions in perception shared by anorexia nervosa and body
dysmorphic disorder may have similar neurobiological origins,” said Wei
Li, a student in the UCLA Interdepartmental Ph.D. Program for
Neuroscience and the study’s first author. “This understanding has the
potential to lead to new strategies that can improve the way we treat
these disorders.”
People with anorexia nervosa have a distorted sense of their body
weight and shape. The disorder, which typically develops in adolescence,
can lead to social withdrawal, cardiovascular or electrolyte
disturbances severe enough to require hospitalization, and even death.
There are few effective treatments, and many symptoms can be life-long.
Individuals with body dysmorphic disorder see themselves as
disfigured and ugly, even though they look normal to others. Those
suffering from the disorder tend to fixate on minute details on their
faces or bodies, and distress with their appearance can result in
depression, anxiety, shame and severe functional impairment, which can
lead to hospitalization and, in some cases, even suicide. The disorder
affects approximately 2 percent of the population, making it more
prevalent than schizophrenia or bipolar disorder — yet scientists know
relatively little about the biology underlying the disease.
Although the two disorders share similar body image distortions, and
are often diagnosed in the same person, no previous study directly
compared the abnormalities in visual information processing that could
significantly contribute to them, nor compared their neurobiology.
“Previously, we knew where these visual processing abnormalities
existed in the brain in body dysmorphic disorder, but did not know when
they were taking place,” said Dr. Jamie Feusner, the paper’s senior
author, a UCLA associate professor of psychiatry and director of the
Obsessive-Compulsive Disorder Program at the UCLA Semel Institute for
Neuroscience and Human Behavior. “Now, knowing the timing, it is clearer
that their perceptual distortions are more likely to be rooted early in
their visual systems.
“Also, the fact that the results were recorded while people were
viewing other people’s faces and images of houses suggests that this may
be a more general abnormality in visual processing,” Feusner said.
The UCLA researchers found that people with anorexia and those with
body dysmorphic disorder showed less activity in the regions of the
brain that convey primarily global information, although the effect
appeared in smaller regions in those with anorexia.
Further, the researchers found that individuals with body dysmorphic
disorder exhibited greater activity in the areas of the brain that
process detailed information. Interestingly, the more activity they had
in these detail-processing regions, the less attractive they perceived
the faces to be, suggesting a connection with distorted perceptions of
appearance.
Both differences were linked to electrical activity occurring within
the first 200 milliseconds after the person viewed an image.
“Among the questions to be answered in future research is whether
this dysfunction improves as a result of treatment, and if not, what
perceptual retraining techniques could help sufferers of these
illnesses,” Li said.
The study’s other authors were Tsz Man Lai, Sandra Loo, Danyale
McCurdy, Michael Strober and Susan Bookheimer, all of UCLA; and Cara
Bohon of Stanford University. Funding for the study was provided by the
National Institutes of Health (NIH MH093535-02S1).