The neurological basis for anorexia nervosa

Most of us know about dieting, and if not first hand, have seen in the news or from friends how hard sticking to a diet long-term can be. This is because adults (regardless of their weight_ resolve to lose weight. Yet, more often than not, that chocolate lava cake is too enticing and that resolve vanishes. This behavior is normal because hunger increases the intensity of food rewards. Yet, individuals with anorexia nervosa (AN), despite their state of starvation, are able to ignore such food-related rewards.

New research now sheds light on the brain mechanisms that may contribute to the disturbed eating patterns of anorexia.To do this researchers examined reward responding in relation to metabolic state (hungry or satiated) in 23 women recovered from AN and 17 healthy women without eating disorder histories (e.g., the comparison group). Importantly women with active AN weren’t studied to reduce potential confounds related to starvation.

The healthy women, when in a state of hunger, showed increased activity in the part of the brain that motivates the seeking of reward, but the women recovered from AN did not. The recovered women also exhibited increased activation of cognitive control circuitry (ventrolateral prefrontal cortex, insula)  regardless of metabolic state. This activation of circuitry is the neurological reinforcement of willpower.

Thus, this study found that women who have recovered from anorexia nervosa show two related patterns of changes in brain circuit function that may contribute to their capacity to sustain their avoidance of food.

First, hunger does not increase the engagement of reward and motivation circuits in the brain. This may protect people with anorexia from hunger-related urges. Second, they showed increased activation of executive ‘self-control’ circuits in the brain, perhaps making them more effective in resisting temptations.

“This study supports the idea that anorexia nervosa is a neurobiologically-based disorder. 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 Dr. Christina Wierenga.

“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.”

The studies findings are the first of their kind, which may offer another way to think about and even treat anorexia.

“This study offers new insights about the brain in AN, which we are using to guide treatment development efforts, and reduce stigma associated with this life-threatening disorder,” added Dr. Walter Kaye.

Like with many things involving the human body, this may not just have implications for anorexia, this may also help the other extreme, chronic overeating.

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

“But these same circuits and processes seem to be engaged ‘in reverse’ for obesity. Thus, this study may have broad implications for the country’s obesity epidemic as well.”

Far too often we see people suffering from depression, anxiety, AN, or any other diagnosis that is seen as “mental,” who are shamed by people that are supposed to help them. No, you can’t “just get over it.” No, you can’t “just be in a better mood.” Or anything in that vein of thought for that matter. More and more, we are seeing actual and physical neurological reasons behind these things, so no it isn’t all “in someones head.”

For anyone who has, or is suffering from any form of mental illness no matter how “big” or “small,” just remember, it isn’t something you just get over. No matter how many times you hear that.

Sources:
Wierenga, C., Bischoff-Grethe, A., Melrose, A., Irvine, Z., Torres, L., Bailer, U., Simmons, A., Fudge, J., McClure, S., Ely, A., & Kaye, W. (2015). Hunger Does Not Motivate Reward in Women Remitted from Anorexia Nervosa Biological Psychiatry, 77 (7), 642-652 DOI: 10.1016/j.biopsych.2014.09.024