Filthiness of immorality: manipulating disgust and moral rigidity through noninvasive brain stimulation as a promising therapeutic tool for obsessive compulsive disorder

The study was designed to test the hypothesis that indirect inhibition of the insula via cathodal transcranial direct current stimulation (tDCS) would decrease disgust and moral rigidity in 36 healthy individuals undergoing 15 min of tDCS over the temporal lobe. To obtain a comprehensive assessment of disgust, we used subjective (affect rating), physiological (heart rate variability [HRV]), and implicit measures (word-fragment completion), and moral judgment was assessed by asking participants to rate the deontological and altruistic moral wrongness of a revised version of the moral foundations vignettes. We found anodal and cathodal stimulations to, respectively, enhance and decrease self-reported disgust, deontological morality, and HRV. Note that these effects were stronger in individuals with higher levels of obsessive compulsive (OC) traits. Because disgust and sensitivity to deontological guilt are among the most impairing features in OC disorder, it is auspicious that cathodal tDCS could be implemented to reduce such symptoms.