Preliminary evidence for the efficacy of single-session transcranial direct current stimulation to the ventrolateral prefrontal cortex for reducing subclinical paranoia in healthy individuals.

OBJECTIVES: Paranoia manifests similarly in subclinical and clinical populations and is related to distress and impairment. Previous work links paranoia to amygdala hyperactivity and reduced activation of the ventrolateral prefrontal cortex (VLPFC), a region thought to regulate amygdala activity. METHODS: This study aimed to reduce subclinical paranoia in 40 undergraduates by increasing activity of the VLPFC via single-session transcranial Direct Current Stimulation (tDCS). A double-blind, crossover (active vs. sham stimulation) design was used. RESULTS: Paranoia significantly decreased after active stimulation (dz  = 0.51) but not sham (dz  = 0.19), suggesting that tDCS of VLPFC was associated with mean-level reductions in paranoia. CONCLUSION: These findings demonstrate preliminary support for the role of single-session active stimulation to the VLPFC for reducing subclinical paranoia in healthy individuals. PRACTITIONER POINTS: In both clinical and subclinical populations, paranoia is related to distress and poorer functional outcomes. Paranoia has been linked to overactivation of the amygdala, a brain region responsible for detecting salience and threat, and reduced activation of the ventrolateral prefrontal cortex (VLPFC), a region thought to modulate and regulate amygdala activity. In this study, transcranial direct current stimulation (tDCS) of the VLPFC reduced self-reported paranoia in healthy undergraduate students. tDCS may be a promising intervention for reducing paranoia in subclinical and clinical populations. Effects were relatively small and require replication with larger subclinical samples and with clinical samples.