Combined antisaccade task and transcranial direct current stimulation to increase response inhibition in binge eating disorder

Abstract

Binge eating disorder (BED) is associated with deficient response inhibition. Malfunctioning response inhibition is linked to hypoactivation of the dorsolateral prefrontal cortex (dlPFC), where excitability could be increased by anodal transcranial direct current stimulation (tDCS). Response inhibition can be assessed using an antisaccade task which requires supressing a dominant response (i.e. saccade) towards a newly appearing picture in the visual field. We performed a double-blind, randomised, placebo-controlled proof-of-concept-study in which we combined a food-modified antisaccade task with tDCS in people with BED. We expected task learning and modulatory tDCS effects. Sixteen people were allocated to a 1 mA condition, 15 people to a 2 mA condition. Each participant underwent the food-modified antisaccade task at three measurement points: baseline without stimulation, anodal verum and sham stimulation at the right dlPFC in a crossover design. The error rate and the latencies of correct antisaccades decreased over time. No tDCS effect on the error rate could be observed. Compared to sham stimulation, 2 mA tDCS decreased the latencies of correct antisaccades, whereas 1 mA tDCS increased it. Self-reported binge eating episodes were reduced in the 2 mA condition, while there was no change in the 1 mA condition. Participants demonstrated increased response inhibition capacities by a task learning effect concerning the error rate and latencies of correct antisaccades over time as well as a nonlinear tDCS effect represented by ameliorated latencies in the 2 mA and impaired latencies in the 1 mA condition. The reduction of binge eating episodes might indicate a transfer effect to everyday life. Given that the reduction in binge eating was observed before tDCS administration, this effect could not be the result of neuromodulation. Randomized clinical trials are needed to fully understand this reduction, and to explore the efficacy of a combined antisaccade and tDCS training for BED.

Can we change binge eating behaviour by interventions addressing food-related impulsivity? A systematic review

“…Six studies were identified as directly targeting the brain for the treatment of impulsivity symptoms in people with binge eating behaviour. More specifically, one study used neurofeedback [44] whereas five studies investigated the effectiveness of non-invasive brain stimulation methods comparing verum with sham stimulation [40][41][42][43]45].…”

“…However, Gay and colleagues [41] did not find a reduction after verum or sham rTMS (10 Hz) over the left DLPFC even after 10 stimulation sessions in terms of binging and purging episodes. Furthermore, there were three studies administering transcranial direct current stimulation (tDCS) [40,42,43]. Burgess and colleagues [40] showed decreased inlab food intake and food craving in patients with BED, and decreased urge to binge eat, particularly in men, following anodal verum tDCS administration (2 mA) over the right DLPFC in comparison to sham stimulation.…”

“…In the two verum conditions, a suppressed urge to binge eat and increased self-regulatory control were demonstrated. A recent randomised proof-ofconcept-study investigated the efficacy of anodal tDCS over the right DLPFC (1 mA vs. 2 mA vs. sham) combined with a food-modified antisaccade task to increase response inhibition skills in BED patients [43]. In the food-modified antisaccade task, participants were instructed to look as fast as possible on the opposite side of the screen when they saw a food picture.…”

“…This makes it hard to draw any conclusions about the efficacy of rTMS. On the other hand, tDCS as another non-invasive neuromodulation approach seemed to be a more fruitful approach to decrease binge eating and food craving because the related studies delivered more consistent findings (significantly greater reduction in real conditions compared to sham conditions) [40,42,43]. However, it is important to note that all neuromodulation studies did not use an active intervention in the control condition, but only a sham stimulation which lowers the impact of these results.…”

“…Furthermore, investigating the efficacy of impulsivity-focusing medications would be valuable given their supposed mechanisms of suppressing appetite and regulating the reward pathway. Another fruitful approach that is worthy to be mentioned are neuromodulation techniques, in particular tDCS [40,42,43]. Moreover, combinations of several interventions seem to be very promising, either the combination of psychotherapy with computer-assisted cognitive trainings [32], pharmacotherapy with behavioural interventions [34], or neuromodulation with computer-assisted cognitive trainings [43].…”