When choosing food, anorexia nervosa patients who took part in a recent study showed significantly greater activity in a brain region associated with habitual behavior, the dorsal striatum, compared to healthy people.

All too many of us make poor choices even when we know negative consequences will result — exactly how much did you drink over the weekend and how bad was your hangover? In the case of people with anorexia nervosa, their repeated decision to eat only low-calorie, low-fat foods can actually lead to starvation. In fact, the mortality rate for anorexia nervosa patients ranks among the highest of any psychiatric disorder.

According to the researchers of the new study, many scientists view anorexia nervosa patients’ unwavering devotion to small portions of low-cal food as an expression of single-minded self-control. However, after entering treatment programs and changing their goals, anorexia patients often cannot change their choices and habits. Instead, they continue choosing the same low-calorie, low-fat foods… with no sign of their all-mighty willpower in sight.

So, what exactly is happening in the brains of anorexia patients as they choose food?

Dorsal Striatum

A research team assembled from New York State Psychiatric Institute, Columbia University, and New York University used fMRI brain scan technology to monitor 21 hospitalized anorexic women as they chose food. Next, the researchers performed the same experiments on 21 healthy women and then compared all the results.

As expected, the women with anorexia nervosa consistently chose fewer high-fat foods than the healthy volunteers. Unsurprisingly, their brain activity also diverged from that of their healthy peers.

In the women with anorexia, the dorsal striatum "lit up" — an MRI tracks blood oxygen level-dependent (BOLD) activity — more than usual. This brain region helps regulate movement and influences learning, memory, sleep, and social behavior. In particular, the dorsal striatum is believed to be instrumental to decision-making as it relates to goal-directed actions and habits.

The anorexia patients also showed greater connectivity in the fronto-striatal circuits when they weighed low-fat food choices (while the healthy volunteers showed greater connectivity for high-fat foods). These fronto-striatal circuits are instrumental to executive function, which includes the brain’s ability to select and perceive important information, to plan and organize, to manipulate working memory, to control behavior, to adapt to change… and to make decisions.

The researchers say their findings suggest new avenues for interventions and treatments, including possible new medications. The team believes their work might provide useful insights with regard to other disorders, including addictive behaviors.

Source: Foerde K, Steinglass JE, Shohamy D, Walsh BT. Neural mechanisms supporting maladaptive food choices in anorexia nervosa. Nature Neuroscience. 2015.