Advances from neuroimaging studies in eating disorders

Abstract

Over the past decade brain imaging has helped better define eating disorder related brain circuitry. Brain research on gray and white matter volumes had been inconsistent, possibly due to the effects of acute starvation, exercise, medication and comorbidity, but newer studies controlled for such effects. Those studies suggest larger left medial orbitofrontal gyrus rectus volume in ill adult and adolescent anorexia nervosa after recovery from anorexia nervosa, and in adult bulimia nervosa. The orbitofrontal cortex is important in terminating food intake and altered function could contribute to self-starvation. The right insula, which processes taste but also interoception, was enlarged in ill adult and adolescent anorexia nervosa, as well as adults recovered from the illness. The fixed perception of being fat in anorexia nervosa could be related to altered insula function. A few studies investigated WM integrity, with the most consistent finding of reduced fornix integrity in anorexia and bulimia nervosa, a limbic pathway important in emotion but also food intake regulation. Functional brain imaging using basic sweet taste stimuli in eating disorders during the ill state or after recovery implicated repeatedly reward pathways, including insula and striatum. Brain imaging that targeted dopamine related brain activity using taste-reward conditioning tasks suggested that this circuitry is hypersensitive in anorexia nervosa, but hypo-responsive in bulimia nervosa and obesity. Those results are in line with basic research and suggest adaptive reward system changes in the human brain in response to extremes of food intake, changes that could interfere with normalization of eating behavior.

Altered interoceptive activation before, during, and after aversive breathing load in women remitted from anorexia nervosa

“…Our findings are also consistent with insular anatomical abnormalities documented in both ill adult and adolescent AN and remitted adults (Frank 2015; Shott et al 2015). …”

Psychological risk factors, cognitive-contextual approaches and neural correlates in eating disorders: an integrative review

“…Several studies, investigating these networks, corroborate the existence of changes in sensorimotor and visual networks in ED patients either in terms of functional connectivity [15,21], which looks at correlations between brain regions [22], or in effective connectivity [23], which establishes causal effects between neural systems.…”

“…Furthermore, functional magnetic resonance imaging (fMRI) is also frequently used, by measuring changes in local blood flow and deoxyhemoglobin levels during brain activation. Other techniques like positron emission tomography (PET) and single photon emission computed tomography (SPECT) are also used, providing information about regional cerebral glucose metabolism or the distribution of neurotransmitter receptors [15].…”

The Role of Psychotropic Medications in the Management of Anorexia Nervosa: Rationale, Evidence and Future Prospects

“…Those studies usually do not test brain neurotransmitters directly, but the response during tasks that test specific behaviors might help in understanding neurotransmitters involved in the brain response [108]. In such studies during fMRI, individuals with AN showed greater brain activation compared to controls when viewing anxiety-provoking food pictures; during taste or monetary reward tasks, individuals with AN tended to show increased activation to unexpected stimulus presentation, while brain response tended to be lower when the specific stimulus was expected [109]. Importantly, a paradigm that specifically targets dopamine-related pathways (prediction error model [110]) suggested increased brain responsiveness in AN, implying high dopamine receptor sensitivity, which is consistent with basic science research.…”