Characterizing cerebral metabolite profiles in anorexia and bulimia nervosa and their associations with habitual behavior

Margaret L Westwater,Paul C Fletcher,Alexander G Murley,Hisham Ziauddeen,Kelly M J Diederen,T Adrian Carpenter

doi:10.1038/s41398-022-01872-7

Abstract

Anorexia nervosa (AN) and bulimia nervosa (BN) are associated with altered brain structure and function, as well as increased habitual behavior. This neurobehavioral profile may implicate neurochemical changes in the pathogenesis of these illnesses. Altered glutamate, myo-inositol and N-acetyl aspartate (NAA) concentrations are reported in restrictive AN, yet whether these extend to binge-eating disorders, or relate to habitual traits in affected individuals, remains unknown. We therefore used single-voxel proton magnetic resonance spectroscopy to measure glutamate, myo-inositol, and NAA in the right inferior lateral prefrontal cortex and the right occipital cortex of 85 women [n = 22 AN (binge-eating/purging subtype; AN-BP), n = 33 BN, n = 30 controls]. To index habitual behavior, participants performed an instrumental learning task and completed the Creature of Habit Scale. Women with AN-BP, but not BN, had reduced myo-inositol and NAA concentrations relative to controls in both regions. Although patient groups had intact instrumental learning task performance, both groups reported increased routine behaviors compared to controls, and automaticity was related to reduced prefrontal glutamate and NAA participants with AN-BP. Our findings extend previous reports of reduced myo-inositol and NAA levels in restrictive AN to AN-BP, which may reflect disrupted axonal-glial signaling. Although we found inconsistent support for increased habitual behavior in AN-BP and BN, we identified preliminary associations between prefrontal metabolites and automaticity in AN-BP. These results provide further evidence of unique neurobiological profiles across binge-eating disorders.

Highlights

Bulimia nervosa (BN) and the binge-eating and purging diagnostic subtype of anorexia nervosa (AN-BP) are complex psychiatric conditions that share core symptoms, including recurrent bingeeating and compensatory behaviors
Affected adolescents demonstrated reduced relative concentrations of N-acetyl aspartate (NAA) in parieto-occipital white matter (WM), and NAA reductions have been observed in the anterior insula in adult women with Anorexia nervosa (AN) [10]
Neuroimaging results Myo-inositol levels were significantly reduced in AN-BP, but not BN, relative to healthy women (β(SE) = −0.55(0.18), t(81) = −2.98, p = 0.004; Fig. 3A)

Summary

Introduction

Bulimia nervosa (BN) and the binge-eating and purging diagnostic subtype of anorexia nervosa (AN-BP) are complex psychiatric conditions that share core symptoms, including recurrent bingeeating and compensatory behaviors (e.g., vomiting). Neuroimaging studies have begun to characterize the neural correlates of these illnesses, identifying alterations in the structure and function of brain regions that subserve learning, self-regulatory control and bodily perception in affected individuals [2–6]. In the context of mental illness, selecting the region based on its putative relevance to the disorder under examination can offer useful ways to begin to understand structure-function relations and their disruption. Affected adolescents demonstrated reduced relative concentrations of N-acetyl aspartate (NAA) in parieto-occipital WM, and NAA reductions have been observed in the anterior insula in adult women with AN [10]. Adults with AN have reduced creatine and myo-inositol (a marker of glial cell integrity [14]) concentrations in dorsolateral prefrontal cortex GM, and lower levels of the composite metabolite ‘Glx’, which reflects both

Results

Discussion

Conclusion