Researcher at the Department of Psychiatry, University of Oxford, Dr Jessica Scaife, lead author of this study published in Pyschiatry Research: Neuroimaging - discovered - using both fMRI whole brain and PPI analyses:
- Frontal pole hyper-activated by high calorie foods in AN, the opposite to controls.
- Reduced functional connectivity in reward patthways and somatosensory regions in AN.
Dr Scaife explains the differences she discovered in the way individuals with anorexia nervosa process food stimuli compared to healthy controls, and the methods she used:
A neural basis of restrictive eating in Anorexia Nervosa
Anorexia nervosa (AN) is a severely debilitating condition with the highest mortality of any psychiatric disorder. It is characterised by the relentless pursuit of self-starvation, despite emaciation. Sadly it remains one of the most challenging problems to treat, with low rates of full recovery and few evidence-based treatments. Our research investigates the neurobiological and psychological processes underpinning AN, and we translate our findings towards the development novel empirically targeted interventions.
The question arises, how do individuals with AN resist the temptation to eat energy dense foods and even prefer low calorie foods, despite starvation? There is some evidence of a neural, brain basis underpinning this puzzle.
Individuals with AN initially experience intense reward from the pursuit of thinness and then weight loss becomes compulsive, indeed parallels have been drawn with other compulsive pathologies such as OCD and addictions. Individuals with AN are often preoccupied by thoughts of food, and they show greater attention to food stimuli in experiments, than healthy controls.
For example, studies using functional magnetic resonance imaging (fMRI) have shown that the brains of individuals with anorexia nervosa process food stimuli differently to healthy controls. The prefrontal cortex (a brain region responsible for cognitive control) is more activated by food stimuli in those with AN, compared to controls. Dysfunction is also seen in regions responsible for processing how rewarding food is, and in areas that respond to internal interoceptive feedback on body state and hunger signals. Our group has previously found that when presented with a choice of food pictures, those with AN report wanting to eat low-calorie food more than high-calorie food, the opposite pattern seen in controls.
The current study aimed to determine the neural correlates of food wanting in AN, comparing the neural responses to high and low-calorie food stimuli under fMRI between 3 groups: individuals currently ill with AN, recovered from AN, and healthy controls. Our findings are novel and intriguing: we found that the frontal pole, a part of the brain responsible for higher order decision-making was differentially hyper activated to high-calorie foods, and under activated to low calorie foods in those with AN, the opposite pattern to controls. This could reflect the active process of extreme behavioural control over the consumption of energy-dense foods in AN, despite starvation with low calorie foods seen as the ‘safe choice’. Those with AN also showed reduced activation in interoceptive regions responsible for monitoring internal body state and hunger, suggesting these regions may not effectively process information regarding biological needs despite malnourishment.
Finally, we found reduced connectivity in neural circuits involved in feeding, reward, and motivation in patients with AN, which may reflect the aberrant pattern of reward that develops in AN: away from food, and towards weight loss. Our findings suggest novel treatment targets for those with AN, which we will further explore in future studies.
Dr Jessica Scaife
Read the full paper in Pyschiatry Research: Neuroimaging.