The Neuroscience of Anorexia Reveals Why It’s So Hard to Treat

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Most of the anorexia patients Dr. Joanna Steinglass sees in the inpatient eating-disorders unit at the New York State Psychiatric Institute have been to treatment before. While in the hospital or a residential treatment center, they generally gained weight and began to eat a wider variety of foods. But after they left, their old anorexic habits returned. They began skipping meals again or returning to their extreme exercise routines. All too soon, it seemed, the gains made in treatment and the hope for recovery that went along with it began to evaporate.

According to the conventional wisdom around eating disorders, these relapses were really a misguided search for control. Or maybe the patients just weren’t ready for recovery yet. Or perhaps these were signs of self-control gone awry, spurred on by friends who marvel at their seemingly endless willpower. Interesting theories, and yet Steinglass disagreed. “Even when people show up at our hospital and want to make changes, they find it tough,” she said.

Now a new study in Nature Neuroscience — which Steinglass co-authored — reveals why people with anorexia often struggle so much to integrate new ways of eating into their lives. In the brain, the behaviors associated with anorexia act a lot like habits, those daily decisions we make without thinking. And habits, according to both the scientific evidence and the colloquial wisdom, are phenomenally difficult to break. This new finding helps explain why anorexia has historically been so hard to treat: Anorexic patients are essentially fighting their own brains in an uphill battle for wellness. But more important, the new research may also point toward new and better ways to help those with the eating disorder overcome it.

Relapses among anorexic patients are all too common; about half of patients who initially respond well to treatment will eventually go back to disordered eating, according to some estimates. “We have little in the way of proven effective treatments for anorexia,” said Walter Kaye, director of the Eating Disorder Treatment and Research Program at the University of California, San Diego. (Kaye was not involved in this new study.) “If we had a better understanding of the cause of anorexia, this would aid in developing better treatment.”

Typically, Steinglass said, when patients are admitted, they tend to frequently eat only small amounts of a very limited variety of low-calorie foods. Part of the recovery process, as recounted in a 2008 study in the American Journal of Clinical Nutrition, is helping them enlarge that variety, and also getting them to include more energy-dense foods (that is, foods that are higher in calories). What Steinglass wanted to know was why so many anorexia sufferers found that step so difficult. In her mind, helping people with anorexia make better decisions about food was a key goal of treatment. But when she searched the literature to find out more about this decision-making process, she came up empty-handed.

To fill that gap, Steinglass and her colleagues at NYSPI decided to conduct a study of their own to figure out how people with anorexia made decisions about what to eat, and whether those findings could provide new ways to help them get well and stay well. Steinglass recruited a group of women recently hospitalized for anorexia (although men do get anorexia, the researchers excluded them from the study to prevent any sex or gender influences on the results) and a similar number of healthy controls. First, she had them rate a series of 76 foods on healthfulness and tastiness. After the participants made their ratings, the researchers took one of the items that they deemed neutral on both qualities. With that item serving as a kind of baseline, the researchers then asked each participant to choose between that food and two other foods, a low-fat option (like carrots) and a high-fat option (like chocolate cake) while their brains were being scanned by fMRI. To make sure the decisions were as accurate as possible, the researchers then required each person to eat the food they had chosen as a snack.

Not surprisingly, the women with anorexia were significantly less likely to choose the cake than the healthy controls. But the brain-imaging data were much more striking. Individuals without eating disorders typically evaluate a variety of criteria when deciding what to eat, such as how hungry they are and how much they like the foods on offer, and their brain-imaging data reflected this. Those with anorexia, however, showed increased activity in the area of the brain called the dorsal striatum, which plays a role in decision-making, reward, and, importantly, habitual behaviors. “It seems that once people get sick, decision-making shifts to a different part of the brain that makes it more difficult to make a nuanced choice. Instead, you see the food and you automatically make a specific choice,” Steinglass said.

These findings confirmed Steinglass’s clinical hunch: Anorexia may be more about decision-making than some form of extreme willpower. When her patients left treatment, they often returned to their old environment, which was filled with cues related to eating-disorder behaviors. These cues, then, triggered the behaviors that her patients had struggled so hard to break. That these behaviors had become habitual on the neurological level was a key finding, since it meant that many with anorexia were making these decisions without being aware of it. However these habits started (and no one really knows exactly why), they became cemented in place. People with anorexia automatically searched the restaurant menu for the lowest-calorie option without even thinking about it. They cut their food into tiny pieces because it was just how they ate. There was nothing deliberate about it. Their routines had become entrenched and remarkably resistant to change. 

Steinglass emphasizes that calling anorexia a “habit,” such as a headline did in the New York Times, doesn’t capture the full story. It’s not just a habit, like biting your nails. Instead, she likes to think of the disorder as being supported by these entrenched routines that must be changed for recovery to occur. And to start helping nudge her patients toward positive progress, Steinglass has begun working with them to change something tiny in their eating routines, like using different cutlery or eating in a new location. These simple switches help shake up the old anorexic routines and make it easier for them to try something new.

Over time, the goal is for the newer, healthier routines to take the place of the older, disordered ones. “It takes time and lots of practice of eating enough to replace the ingrained behavior of restriction. This is critical for understanding why short-term treatment models predicated on insurance coverage are inadequate for creating lasting behavior change,” said Lauren Muhlheim, an eating-disorders therapist in Los Angeles. Ultimately, Steinglass says, the goal of treatment is to make recovery and wellness habits of their own, so that one day returning to the illness will be as incomprehensible as recovery once was.