Interhemispheric paired associative stimulation targeting the bilateral prefrontal cortex of subjects with obesity and food addiction modulates food-related emotional reactivity and associated brain activity

Purpose: Behavioral and neurobiological abnormalities in addiction and obesity have led to the theory of food addiction in obesity (FAOB) and brain-behavior association studies. Transcranial magnetic stimulation (TMS) studies and treats various brain disorders. Cortico-cortical paired associative stimulation TMS protocol, in which left lateral prefrontal cortex (LPFC) stimulation follows right LPFC stimulation, can reduce emotional reactivity to visual triggers and modulate prefrontal asymmetry in healthy adults. Accordingly, we examined the effects of acute ccPAS on food cravings and brain responses in FAOB. Methods: Twenty-two adults (12 Active, 10 Sham) with FAOB participated in this single-blind, sham-controlled pilot study. Electroencephalogram was recorded during rest and a Food Stroop task, which were conducted before and after a single active or sham ccPAS session, consisting of 600 paired stimulation pulses of the right, then left LPFC, with inter-pulse interval of 8ms and a 3sec inter-pair-interval. Stroop bias changes following exposure to food images, alterations in the associated (emotionally laden) late positive event-related component (LPPb) total brain activity power, and frontal alpha band asymmetry during rest and task performance were investigated. Results: No baseline differences were detected between the groups, except for education level. Active (but not Sham) ccPAS elevated the Stroop bias and the total brain activity power over the left LPFC while no stimulation- related influence was found on the LPPb or prefrontal brain asymmetry during task and the resting state. However, the stimulation-induced change in the Stroop bias was negatively correlated with the change in LPPb magnitude, positively correlated with changes in asymmetrical activity during the task, and negatively with left frontal alpha asymmetry during rest. Conclusions: The ccPAS affected food-related emotional regulation, probably due to general reduction of inhibitory control during task performance. Further studies are needed to affirm the results with larger samples and to elucidate the development of beneficial ccPAS protocol for obesity with food addiction.