Citation: Ghayebzadeh, S.; Zardoshtian, S.; Amiri, E.; Giboin, L.-S.; Machado, D.G.d.S. Anodal Transcranial Direct Current Stimulation over the Right Dorsolateral Prefrontal Cortex Boosts Decision Making and Functional Impulsivity in Female Sports Referees. Life 2023, 13, 1131. https:// doi.org/10.3390/life13051131 Academic Editors: Peter Walla, Andrés Molero-Chamizo and Guadalupe Nathzidy Rivera-Urbina Received: 4 April 2023 Revised: 20 April 2023 Accepted: 3 May 2023 Published: 5 May 2023 Copyright: © 2023 by the authors. Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https:// creativecommons.org/licenses/by/ 4.0/). life Article Anodal Transcranial Direct Current Stimulation over the Right Dorsolateral Prefrontal Cortex Boosts Decision Making and Functional Impulsivity in Female Sports Referees Shahrouz Ghayebzadeh 1 , Shirin Zardoshtian 1, *, Ehsan Amiri 1 , Louis-Solal Giboin 2 and Daniel Gomes da Silva Machado 3, * 1 Faculty of Sport Sciences, Razi University, Kermanshah 6714414971, Iran; eamiri.tmu@gmail.com (E.A.) 2 EFOR-CVO, 69003 Lyon, France; lsgiboin@soladis.ch 3 Research Group in Neuroscience of Human Movement (NeuroMove), Department of Physical Education, Federal University of Rio Grande do Norte, Natal 59078-970, RN, Brazil * Correspondence: zardoshtian2014@gmail.com (S.Z.); profdmachado@gmail.com (D.G.d.S.M.) Abstract: We investigated the effect of anodal transcranial direct current stimulation (tDCS) over the right dorsolateral prefrontal cortex (rDLPFC) on the sensitive decision making of female team sports referees. Twenty-four female referees voluntarily participated in this randomized, double- blind, crossover, and sham-controlled study. In three different sessions, participants received either anodal (a-tDCS; anode (+) over F4, cathode (-) over the supraorbital region (SO)), cathodal (c-tDCS; -F4/+SO), or sham tDCS (sh-tDCS) in a randomized and counterbalanced order. a-tDCS and c-tDCS were applied with 2 mA for 20 min. In sh-tDCS, the current was turned off after 30 s. Before and after tDCS, participants performed the computerized Iowa Gambling Task (IGT) and Go/No Go impulsivity (IMP) tests. Only a-tDCS improved IGT and IMP scores from pre to post. The delta (Δ = post–pre) analysis showed a significantly higher ΔIGT in a-tDCS compared to c-tDCS (p = 0.02). The ΔIMP was also significantly higher in a-tDCS compared to sh-tDCS (p = 0.01). Finally, the reaction time decreased significantly more in a-tDCS (p = 0.02) and sh-tDCS (p = 0.03) than in c-tDCS. The results suggest that the a-tDCS improved factors related to sensitive decision making in female team sports referees. a-tDCS might be used as an ergogenic aid to enhance decision performance in female team sports referees. Keywords: dorsolateral prefrontal cortex; sports referees; impulsivity; performance; sensitive decision making; transcranial electrical stimulation 1. Introduction Transcranial direct current stimulation (tDCS), also known as a neurodoping or neu- roenhancement technique, has been widely used in sports-related studies over the last two decades [1,2]. tDCS induces its effects by changing the excitability of the target areas in the brain in a polarity-specific manner [3]. It has been shown that anodal and cathodal stimulation increase and decrease the excitability of the areas of interest, respectively [4]. The positive effects of tDCS on muscular strength and whole-body endurance performance, power output, and cognitive function in healthy and clinical populations have been re- ported in several studies [5–11]. These promising results have paved the path for the investigation of the efficacy of tDCS in other target populations and conditions related to sports activities. One such target population is sports referees, who are an integral part of any sports event, since their decisions might have a big impact on the results of a game [12]. For many referees, sports events bring tempting moments, high expectations for making the right decisions, and ample potential to influence the outcome [12–14]. Such circumstances particularly exist for referees who need to consider multiple hints as they interact with Life 2023, 13, 1131. https://doi.org/10.3390/life13051131 https://www.mdpi.com/journal/life