Acute effects of baclofen, a γ-aminobutyric acid-B agonist, on laboratory measures of aggressive and escape responses of adult male parolees with and without a history of conduct disorder

Abstract

Rationale: The possible role of γ-aminobutyric acid (GABA) in human aggression was evaluated by administering baclofen, a GABA-B agonist and comparing the effects on laboratory measures of aggression and escape among subjects with and without a history of conduct disorder. Methods: Twenty male subjects with a history of criminal behavior participated in experimental sessions, which measured aggressive and escape responses. Ten subjects had a history of childhood conduct disorder (CD+) and ten control subjects had no history of CD. Aggression was measured using the point subtraction aggression paradigm (PSAP), which provides subjects with aggressive, escape, and monetary-reinforced response options. Results: Acute doses (0.07, 0.14 and 0.28 mg/kg) of baclofen had remarkably different effects on aggressive responses among CD+ subjects relative to control subjects. Aggressive responses of CD+ subjects decreased, while aggressive responses of control subjects increased following baclofen administration. Baclofen decreased escape responses for both CD+ and control subjects. No changes in monetary-reinforced responses were observed, indicative of no central nervous system stimulation or sedation. Conclusions: The GABA-B agonist baclofen suppressed aggressive responses in subjects with a history of childhood CD, while producing the opposite effect in control subjects. These suggest a possible unique role for GABA in the regulation of aggression in CD+ population.