Habit-related brain circuits activated in patients with eating disorders

Brain scans of people with binge eating disorder or bulimia show altered activity in regions associated with habit formation, suggesting new possibilities for treating eating disorders¹.

Habitual behaviors are automatically triggered by external cues. For example, reaching for your seat belt as soon as you get in the car. Scientists have identified two regions of his lab rat that are active when performing habitual behaviors in a part of the brain called the striatum. The human brain is somewhat similar to the rat brain, but neuroscientists weren’t sure what the analogous structure of the human brain was, or even if such a structure existed.

Alan Wang, a neuroscientist at the Stanford University School of Medicine in California, and his colleagues examined which areas of the rat brain cortex are connected to the striatum. Then, using high-resolution magnetic resonance imaging data from 178 participants in his Human Connectome Project, an initiative to map the human brain, working backwards from the cortex, we can We identified candidate brain regions.

This led to two structures, the sensorimotor putamen and the connective caudate.

Habitual behavior is likely involved in bulimia and bulimia nervosa, so the team examined the brains of 34 women with either of these disorders to see if there was altered activity in the two structures. has been confirmed.

Functional magnetic resonance imaging revealed changes in these areas in people with eating disorders compared with those without eating disorders. The images showed changes in gray matter structure and dopamine signaling specifically in the sensorimotor putamen.

changed connection

In individuals with binge eating disorder or bulimia, connections between parts of the cortex and the habit-enhancing sensorimotor putamen were much stronger than in healthy controls. However, there was increased connectivity to the orbitofrontal cortex and motor cortex.

“Connectivity with the sensorimotor putamen was the main differentiator between the control and bulimic groups we examined,” says Wang.

“This study adds fairly nicely to some evidence suggesting that brain circuits involving the putamen are likely involved in binge eating behavior,” said Icahn School of Medicine, Mount Sinai, New York City. University psychiatrist Laura Verner says:

The degree of difference in brain scans was directly related to self-reported descriptions of eating disorder severity.

Dopamine is a neurotransmitter released in response to reward, and researchers hoped that the brains of people with eating disorders would show the effects of repeated reward exposure. seems to have fewer receptors for dopamine than in healthy brains, and researchers believe that increased dopamine release may reduce the sensitivity of dopamine receptors, reducing their numbers. .

The researchers caution that the sensorimotor putamen and associative caudate nucleus cannot be definitively identified as the human equivalent of the habit-forming region of the rat striatum, but this study does not support habit formation. Open new avenues for exploration.

It also suggests that new treatments for binge eating disorder and bulimia should be explored. In the past, these conditions have been resistant to treatment. Psychiatrist Joanna Steingras of Columbia University Irving Medical Center in New York City says bulimia is probably the most common eating disorder, but “the least studied in terms of biobehavioral mechanisms.”

Wang said the study could pave the way for treatments that target brain regions involved in such disorders using techniques such as deep brain stimulation and transcranial magnetic stimulation. increase. He speculates that future treatments for many psychiatric disorders, not just bulimia or bulimia, may target brain circuits directly.