Increased resting state functional connectivity in the fronto-parietal and default mode network in anorexia nervosa.

Ilka Boehm,Yacila Deza Araujo,Jessika Weiss,Franziska Ritschel,Daniel Geisler,Stefan Ehrlich,Joseph A King,Martin Walter,Juliane Petermann,Heidi Lohmeier,Maria Seidel,Veit Roessner

doi:10.3389/fnbeh.2014.00346

Abstract

The etiology of anorexia nervosa (AN) is poorly understood. Results from functional brain imaging studies investigating the neural profile of AN using cognitive and emotional task paradigms are difficult to reconcile. Task-related imaging studies often require a high level of compliance and can only partially explore the distributed nature and complexity of brain function. In this study, resting state functional connectivity imaging was used to investigate well-characterized brain networks potentially relevant to understand the neural mechanisms underlying the symptomatology and etiology of AN. Resting state functional magnetic resonance imaging data was obtained from 35 unmedicated female acute AN patients and 35 closely matched healthy controls female participants (HC) and decomposed using spatial group independent component analyses (ICA). Using validated templates, we identified components covering the fronto-parietal “control” network, the default mode network (DMN), the salience network, the visual and the sensory-motor network. Group comparison revealed an increased functional connectivity between the angular gyrus and the other parts of the fronto-parietal network in patients with AN in comparison to HC. Connectivity of the angular gyrus was positively associated with self-reported persistence in HC. In the DMN, AN patients also showed an increased functional connectivity strength in the anterior insula in comparison to HC. Anterior insula connectivity was associated with self-reported problems with interoceptive awareness. This study, with one of the largest sample to date, shows that acute AN is associated with abnormal brain connectivity in two major resting state networks (RSN). The finding of an increased functional connectivity in the fronto-parietal network adds novel support for the notion of AN as a disorder of excessive cognitive control, whereas the elevated functional connectivity of the anterior insula with the DMN may reflect the high levels of self- and body-focused ruminations when AN patients are at rest.

Highlights

Anorexia nervosa (AN) is characterized by a disturbed body image, constant preoccupations with weight and shape and an intensive fear of weight gain that lead to severe dietary restriction and weight loss (American Psychiatric Association, 2013)
To capture possible abnormalities of brain networks corresponding to typical AN symptom domains and popular hypotheses on the etiology of AN as introduced above, we focused on the following resting state networks (RSN): the frontoparietal network to investigate the notion of excessive cognitive control, the salience network to understand the suspected aberrant processing of rewarding and emotional stimuli in AN, the visual and somatosensory networks to uncover possible neural correlates of the body image distortion and the default mode network (DMN) related to self-referential processing including disorder-typical rumination
10 components were identified as RSNs of interest (Figure 1) and five components were identified as artifacts

Summary

Introduction

Anorexia nervosa (AN) is characterized by a disturbed body image, constant preoccupations with weight and shape and an intensive fear of weight gain that lead to severe dietary restriction and weight loss (American Psychiatric Association, 2013). Additional common symptoms include perfectionism, excessive physical activity, alexithymia and disturbed interoceptive awareness (Lilenfeld et al, 2006). Given the variety of AN symptoms, different research approaches and hypotheses have been pursued in the last decade. Some researchers have focused on executive functioning and volition and have described AN as a disorder of enhanced higher-order cognitive control functions (Kaye et al, 2009, 2013; Zastrow et al, 2009). Others have targeted the presumably impaired processing of rewarding and emotional stimuli (Wagner et al, 2007b; Brooks et al, 2011; Oberndorfer et al, 2011; Frank et al, 2012; Bischoff-Grethe et al, 2013).

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