New York: While healthy individuals find it very difficult to resist the temptation of a mouth-watering delicacy, especially when they are hungry, anorexics face no such trouble as hunger does not increase their intensity of food rewards, says a new study.
The study published in the journal Biological Psychiatry, sheds new light on the brain mechanisms that may contribute to the disturbed eating patterns of anorexia.
"Hunger is a motivating drive and makes rewards more enticing," said Christina Wierenga, associate professor of psychiatry at University of California, San Diego.
"We have long been puzzled by the fact that individuals with anorexia nervosa (AN) can restrict food even when starved," Wierenga noted.
They 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).
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.
Women who have recovered from anorexia nervosa showed 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," Wierenga noted.
The researchers concluded that unlike others, hunger does not motivate anorexics to eat.