How Anorexics Control Appetite

Anorexic patients may not experience the reward-based motivation for food that drives many individuals to eat, which would explain how they are able to control their appetite.

Researchers found 2 related patterns of changes in the brain circuit function of women who have recovered from anorexia nervosa (AN) that may contribute to their capacity to sustain their avoidance of food.

When hungry, former AN patients do not exhibit the increased activity in the part of the brain responsible for reward motivation that is found in the brains of healthy patients, which may shield them from urges to eat. Additionally, recovered AN patients show increased activity in the executive “self-control” circuits in the brain, which may enable them to resist food-related temptations more effectively.

These findings led the research team to speculate that hunger does not engage the brain’s reward and motivation circuits in anorexic patients, thereby preventing them from experiencing hunger-related urges and helping them resist the temptation of reward.

“We've long been puzzled by the fact that individuals with AN can restrict food even when starved. Hunger is a motivating drive and makes rewards more enticing,” said study co-author Christina Wierenga, PhD, in a press release. “These findings suggest that AN individuals, even after recovery, are less sensitive to reward and the motivational drive of hunger. In other words, hunger does not motivate them to eat.”

“Anorexia nervosa is a devastating illness, and this study sheds new light on brain mechanisms that may enable people to starve themselves,” added Biological Psychiatry Editor John Krystal, MD. “In identifying these mechanisms, this work may provide circuit-based targets for therapeutics.”

Practice Points

Pharmacists can play a vital role in treating patients with eating disorders. In an exclusive interview with Pharmacy Times, Dr. Wierenga provided the following insights and counselling recommendations:

• Since there are currently no FDA-approved medications for the treatment of AN or bulimia, and only 1 drug (Vyvanse) is approved to treat binge-eating disorder, many patients with eating disorders are prescribed psychotropic or other medications to treat co-occurring disorders, such as depression or anxiety. Pharmacists can manage adherence to these drugs and look for potential adverse effects or interactions.
• Many patients with eating disorders are nervous about taking medication, sometimes due to fears that they will gain weight as a result. Pharmacists can address these concerns and educate patients on the benefits of treatment.
• While many eating disorders can go undiagnosed for several months to years after initial onset, pharmacists are nevertheless in a unique position to look for warning signs, which may include rapid weight loss or gain, lack of expected weight or height for development, electrolyte abnormalities, bradycardia, and the absence of menstruation.
• Pharmacists can also look for signs of compensatory weight loss behaviors, such as use of diet pills, OTC supplements, laxatives, ipecac, or diuretics, and insulin misuse in individuals with diabetes.
• Pharmacists who identify a symptom of an eating disorder such as AN should speak directly to the patient or, if the patient is an adolescent, the parents. Because the patient may be ashamed of the eating disorder or deny it entirely, pharmacists should also obtain consent to speak to the patient's primary care provider to assist in referring the patient to an eating disorder specialist.

“It takes a team to treat eating disorders, and a pharmacist can help coordinate care and be a member of the team,” Dr. Wierenga told Pharmacy Times. “Because anorexia is a life-threatening disorder with the highest mortality rate of any psychiatric disorder, treatment is imperative. If a disorder is formally diagnosed, the pharmacist is encouraged to work collaboratively with the patient's treatment team to support the treatment plan and insure medication adherence.”