Dorsolateral Prefrontal γ-Aminobutyric Acid in Men Predicts Individual Differences in Rash Impulsivity

Background: Impulsivity is a multifaceted personality construct associated with numerous psychiatric disorders. Recent research has characterized four facets of impulsivity: urgency (the tendency to act rashly especially in the context of distress or cravings); lack of premeditation (not envisaging the consequences of actions); lack of perseverance (not staying focused on a task); and sensation seeking (engaging in exciting activities). Urgency is particularly associated with clinical populations and problematic disinhibited behavior. Methods: We used magnetic resonance spectroscopy to measure concentration of the inhibitory neurotransmitter gamma-aminobutyric acid (GABA) in the dorsolateral prefrontal cortex (DLPFC) in two cohorts of 12 and 13 participants. Results: We find that variation in trait urgency in healthy men correlates with GABA concentration in the DLPFC. The result was replicated in an independent cohort. More GABA predicted lower urgency scores, consistent with a role in self-control for GABA-mediated inhibitory mechanisms in DLPFC. Conclusions: These findings help account for individual differences in self-control and thus clarify the relationship between GABA and a wide range of psychiatric disorders associated with impaired self-control.