Consequences of prefrontal tDCS on inhibitory control and reactive aggression

Abstract

Increased aggression and impulsivity represent a key component of several psychiatric disorders, including substance use disorder, which is often associated with deficient prefrontal brain activation. Thus, innovative tools to increase cognitive control are highly warranted. The current study investigates the potential of transcranial direct current stimulation (tDCS), a tool to modulate cortical activation, to increase cognitive control in individuals with a high potential for impulsive and aggressive behavior. In a double-blind, sham-controlled study, we applied anodal tDCS over the right dorsolateral prefrontal cortex in an all-male sample of alcohol dependent patients (AD), tobacco users (TU) and healthy controls (HC) who completed the Taylor Aggression Paradigm and Stop Signal Task twice. While there were no observable effects of tDCS in controls, results revealed altered aggressive behavior in AD following active stimulation. Specifically, these individuals did not show the standard increase in aggression over time seen in the other groups. Furthermore, improved response inhibition was found in AD and TU following active but not sham stimulation. Our study demonstrates that prefrontal tDCS improves our laboratory measure of impulse control in at-risk groups, illustrating the importance of sample characteristics such as nicotine intake and personality traits for understanding the effects of brain stimulation.

Transcranial direct current stimulation combined with alcohol cue inhibitory control training reduces the risk of early alcohol relapse: A randomized placebo-controlled clinical trial

“…However, it should be noted that significant inter-individual variability in executive performance in response to prefrontal tDCS exists. A recent study by Weidler et al [83] found evidence for this, wherein the upregulation of right DLPFC improved response inhibition performance among alcohol and tobacco-dependent patients in the stopsignal task administered 40 min after the stimulation as opposed to healthy controls (characterized by lower impulsivity traits).…”

Non‐invasive neuromodulation can reduce aggressive behaviors in humans: A critical perspective

“…Several studies documented a relation between alcohol consumption and aggressive crimes, such as homicides, assaults, and rapes [84][85][86][87]. tDCS modulated aggressive behavior in a male sample of Alcohol-Dependent (AD) patients [88]. After a-tDCS stimulation…”

“…Furthermore, many studies have enrolled male participants only, making it impossible to investigate potential gender effects [88,90,94,96]. Further methodological limitations concern the single tDCS sessions and absence of follow-up measures [30,33,39,41,46,48,52,88]; indeed, given that the literature focuses on the acute effects of the stimulation (i.e., immediately after the stimulation), no evidence is available for the long-term effects. In addition, limited sample sizes (approximately 30 participants) might represent an obstacle for results generalization [21,33,39,41].…”

“…Several studies documented a relation between alcohol consumption and aggressive crimes, such as homicides, assaults, and rapes [84–87]. tDCS modulated aggressive behavior in a male sample of Alcohol‐Dependent (AD) patients [88]. After a‐tDCS stimulation (1.5 mA × 20 min) over rDLPFC, AD patients showed less reactive aggressive behavior as measured with the Modified Taylor Aggression Paradigm [89], while no variations emerged in tobacco users (TU) [88].…”

“…5 mA × 20 min) over rDLPFC, AD patients showed less reactive aggressive behavior as measured with the Modified Taylor Aggression Paradigm[89], while no variations emerged in tobacco users (TU)[88]. Smits et al[90] found a null effect of tDCS on aggressiveness.Authors recruited a military sample with PTSD or impulsive aggression and performed a-tDCS stimulation over the right Inferior Frontal Gyrus (IFG) coupled with inhibitory control training.Aggressiveness and impulsiveness were measured through theState-Trait Anger Expression Inventory (STAXI-2;[91]); the PTSD Checklist for DSM-5 (PCL-5;[92]); a go/no go task; and an Implicit Association Task (IAT;[93]).…”