Anodal stimulation of inhibitory control and craving in satiated restrained eaters

ABSTRACT

Objectives

Eating and weight disorders are severe and complex clinical conditions which, among other behaviors, include (attempts at) restrained eating, food avoidance, following dietary rules, and overeating. Comparable to women with obesity, restrained eaters (RE) without formal eating disorder diagnosis are worse at inhibiting their motor responses than unrestrained eaters (URE). According to neuroimaging studies, the right inferior frontal gyrus (rIFG) is involved in inhibitory control which, in turn, could be improved by neuromodulation such as anodal transcranial direct current stimulation (tDCS) across rIFG.

Methods

This double-blind sham-controlled cross-over study was conducted after a standardized breakfast. Normal-weight female RE und URE performed a stop-signal task (SST) with food and non-food stimuli during sham or anodal tDCS. Food craving, hunger, and satiety were self-reported before and after tDCS. We employed a mixed between-subjects (group: RE vs. URE) and within-subjects factorial design (tDCS: anodal tDCS vs. sham; stimuli: food vs. control pictures).

Results

Breakfast consumption was comparable for RE and URE, as well as craving, hunger, and thirst. Regarding inhibitory control, a significant two-way interaction between group and tDCS ermerged: RE had longer stop-signal reaction times (SSRTs) during sham tDCS, but they improved to the level of URE by application of anodal tDCS.

Discussion

Results replicated an inhibitory control deficit in RE with longer SSRTs compared to URE without stimulation. During anodal tDCS to the rIFG, reduced SSRTs in RE indicated an improvement in inhibitory control. The findings suggest a specificity of rIFG stimulation in at-risk groups with regards to inhibitory control irrespective of craving.

KEYWORDS:

• Restrained eating
• inhibitory control deficit
• anodal transcranial direct current stimulation
• tDCS

Subject classification codes::

• Behavior

Acknowledgements

We wish to thank Daniela Gutbrods, Sarah Sekinger, Adelina Müller, and Ines Armbruster for their help with data collection.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

The author(s) reported there is no funding associated with the work featured in this article.

Notes on contributors

Philipp A. Schroeder

Philipp A. Schroeder is a postdoctoral researcher at the Department of Psychology at the University of Tübingen, Germany. His research in clinical psychology and behavioral neuroscience is focused on controlled and un-controlled aspects of cognition, both in general and in relation to food. In his studies, he employs virtual reality (VR) for behavior tracking and neuromodulation (tDCS) for experimental manipulations of the neural underpinnings of cognitive control and implicit associations.

Maryam Farshad

Maryam Farshad is a PhD student in the Department of Clinical Psychology and Psychotherapy in Professor Jennifer Svaldi's research group at the University of Tübingen, Germany. With a strong interest in brain and neuroimaging and neurophysiological methods (tDCS, fNIRS, EEG/ERP), she is currently focusing on non-invasive brain stimulation methods for modulating regulated and automatic human behavior.

Jennifer Svaldi

Jennifer Svaldi is a full professor of clinical psychology at the University of Tübingen and director of the adjoint Psychotherapy Outpatient Clinic. Research themes of JS focus on mechanisms that cause and maintain pathological eating behavior and body image disturbances in at-risk populations, overweight individuals and individuals with eating disorders. To this end, a variety of designs and methods are used, ranging from fundamental studies (eye tracking, EEG, reaction-time tasks) to laboratory-based behavioral studies, ecological momentary assessment (EMA) studies and applied clinical studies (treatment processes and treatment effects).