Individuals with anorexia nervosa restrict food intake, sometimes to the point of starvation. And yet, a new study published in The Journal of Neuroscience finds the cognitive machinery they use to make decisions about what to eat is remarkably similar to that of healthy eaters.
Instead, the difference lies in the brain regions that supply evidence to the decision, the University of Chicago researchers found. Participants without anorexia showed hippocampal activation as they weighed food choices, whereas those with anorexia recruited the striatum too.
The findings suggest that those with anorexia rely on different inputs that lead to restrictive food choices, rather than a maladaptive decision process per se. UChicago Asst. Prof. Akram Bakkour, who was on the research team, explained the significance of the brain regions and said the findings could help target new eating disorder interventions.
“The hippocampus is at the center of this flexible memory system,” Bakkour said. “We think about episodic memory as being very flexible, and it allows us to travel back in time, but we can also think about the future. It’s important for planning. The striatum, on the other hand, really is at the heart of a pretty inflexible memory system. It’s been implicated in habit learning, for example. It helps us learn habits, but also to sustain habits over time.”
To separate valuation from other aspects of decision-making, the research team had participants make food choices and complete a perceptual decision-making task, in which they judged the predominant color in a display of flickering dots.
This allowed the researchers to test whether any differences in the decision process were specific to food or reflected broader alterations in how decisions are made. They combined computational modeling that captures both choices and reaction times simultaneously with fMRI to examine the underlying cognitive and neural mechanisms of food choice.
Consistent with prior research, patients with anorexia consistently chose low-fat foods and avoided high-fat foods, whereas healthy controls neither preferred nor avoided fatty foods. But once those preference differences were accounted for, the decision-making process itself looked the same across groups. Both groups were faster and more accurate on easier decisions, and the model fit both groups’ behavior equally well, with no differences in key parameters such as the rate of evidence accumulation or the amount of evidence required to commit to a choice.
Contrary to the researchers’ expectations, the findings indicate that anorexia does not involve a breakdown in the cognitive process of deliberation for either food or non-food decisions. Instead, these results shift the focus to the input to the decision process, or the valuation stage, that leads individuals to choose one food over another.
Where the groups did diverge was in the brain. The fMRI results showed greater hippocampal activation in the control group during food choice deliberation, specifically as decision time increased, compared with perceptual decisions.
Patients with anorexia showed a similar hippocampal effect but additionally recruited the striatum. The researchers interpret the results to suggest that individuals with anorexia recruit different neural systems to compute and generate internal evidence as inputs to the decision process.
Bakkour said this means the source of evidence for decision-making in anorexia may be drawn from a more rigid system, whereas healthy individuals draw on a more flexible one. The direction of causality is still unknown, and it remains unclear whether striatal involvement is a cause or consequence of the disorder.
The team will next explore the attributes that contribute most strongly to choice and valuation between patients with anorexia and those without. But as Bakkour and his colleagues continue to probe the behavioral decision-making angle behind the disorder, they may open new treatment opportunities.
“That might give us some hope that maybe we can move things around,” Bakkour said. “If we can just tip the balance a little bit more toward the hippocampus in the patients, maybe we would normalize decisions.”
If you or someone you know is struggling with an eating disorder, the National Alliance for Eating Disorders helpline is available at 1-866-662-1235. UChicago students can reach Student Wellness at 773-702-3625.
—This article originally appeared on the Social Sciences Division website.
