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Lock patterned his research after a study published the year before from Columbia University. And though his results differed from that one, the two together may provide insight into what happens in the brain when adolescent girls with bulimia become adult women.
The first time she stole something, Jacky Duong felt electrified. She was sixteen, walking down a store aisle with her mother. A box of candy caught her eye. She remembered that she had just eaten a sandwich, and wanted to keep bingeing. So she took the box, found a secluded aisle, unwrapped it, and devoured its contents on the spot. Of course, it wouldn't stay down for long.
Stealing opened new possibilities, Duong remembered thinking. If she could get a free lunch, what else could she get for free? In her mind, she saw the window display of a department store, illuminating the trendy clothes and sparkling jewelry that teenage girls covet. Before long she started swiping plastic rings, silk scarves, and designer boots. The things she stole all had one thing in common: They all fit in her purse.
The more Duong gave in to the urge to vomit, the more she felt the need to steal from stores. The two fed off each other. Soon she was taking jewelry she didn't need, clothes she didn't want. Stolen goods piled up in her closet until she was literally giving them away. But she couldn't stop. "It was empowering," she said. "I was invincible. I was, like, 'I can eat all the food I want and not get fat; I can get all the pretty things I want without paying.'"
To Duong, both of her urges represented a hunger for control — over her image, her appearance, and, ultimately, herself. "It stemmed from something deeper," she said.
Then once Duong entered college, the restrictions her parents placed on her eating and bingeing disappeared. Bulimia began taking up a disproportionate amount of her time. The turning point came during her second semester, when she was forced to quit the campus Taekwondo team because she was too weak to compete. Her grades had started slipping.
"I spent my entire fall semester staring at three walls — the stall of a bathroom," she said.
In February of her freshmen year, Duong realized that her eating disorder had gotten out of control. She withdrew from her classes to look for a recovery program.
The answer came while she was getting a blood test at a nearby medical center. A nurse asked her, as part of a routine survey, if she was having suicidal thoughts.
She was, she said.
She was sent by ambulance to a 75-hour holding station, then voluntarily enrolled in an inpatient-outpatient program at the Center for Anorexia and Bulimia at Alta Bates Summit Medical Center.
She had almost given up the fight.
The image the media paints of eating disorders is unflattering at best. It's portrayed as a Hollywood disease of decadence and superficiality, relegated to image-conscious dancers (think of films like Center Stage and Black Swan) and movie stars like Lindsay Lohan who "starve" for attention. Jacky's father calls bulimia "the queen's disease," because only the rich can afford to throw money down the toilet.
Similarly, shoplifting is viewed with strong disdain. Moreover, compulsive shoplifters know there can be a high price for their actions — imprisonment, fines, and public humiliation, to name a few. They don't need what they take, and many report guilt for their actions. So why do they keep doing it?
Dr. Rachel Marsh, a pediatric neuroimager who studies bulimia at Columbia University, was the first to try a brain-based impulse test to get to the root of the disorder in 2009. Like Lock, she believes the key to getting at the origin of the disease is to study how bulimia develops through adolescence. Also like Lock, she focuses on the frontostriatal circuits, the brain's centers for reward and impulse control.
Marsh, whose interest in eating disorder stems from her earlier work on Tourette's syndrome, compares the need to overcome the binge-purge impulse in bulimia to suppressing the "tic" in Tourette's: "It's the same way that a girl presented with a whole table of food needs to inhibit the impulse to eat it very quickly," she said. "They can do it — it's just very difficult."
Unlike Lock, Marsh is not a clinician — she studies brains, not patients. According to her, the frontostriatal circuits, which are mediated by chemicals including dopamine and serotonin, harden during adolescence — roughly the same time that an eating disorder sets in. "Probably these deficiencies [in brain circuits] allow these behaviors to crystallize into habits," Marsh said.
In her 2009 study, Marsh looked at adult women, and the results were different from what Lock found with adolescent girls. Her twenty bulimic patients had longer response times and made more errors on the test she administered. And while the bulimic teens that Lock studied showed lots of brain activity, suggesting a fierce battle inside their brains, the bulimic women that Marsh studied showed less activation in their frontal lobes.
Like so much about eating disorders, there may be many reasons for why Marsh and Lock's results were different. It could be that the task Marsh used was more difficult. But it could also be that her patients were older and had suffered from their eating disorders for longer, leaving more time for their brains to undergo changes. Perhaps their impulse control pathways were no longer capable of putting up the same resistance.