The effects of diazepam on human self-aggressive behavior

Rationale: Diazepam, a benzodiazepine with a relatively rapid onset of clinical effects, has been associated with suicide and other self-aggressive acts. The evidence for this association, however, comes exclusively from retrospective non-experimental studies. Although suggestive, the results of these studies do not support a cause-and-effect relationship between benzodiazepine consumption and self-aggressive behavior. Objective: To experimentally examine the effect of diazepam on human self-aggressive behavior under controlled laboratory conditions. Method: Forty-six healthy men and women were randomly assigned to receive placebo, or 5 mg or 10 mg diazepam in a double-blind, between-groups design. Participants were then provided the opportunity to self-administer electric shocks during a competitive reaction-time task (the self-aggression paradigm, SAP). Self-aggression was defined by the intensity of shock chosen. Results: Diazepam (10 mg) was associated with higher average shock self-administered than placebo. Subjects receiving 10 mg diazepam were also more likely to attempt to self-administer a shock that they were led to believe was "severe" and painful. Sedation effects were found, but diazepam consumption did not impair memory, attention, concentration, pain threshold, or reaction-time performance. Conclusions: Clinically relevant diazepam doses may be associated with self-aggressive behaviors at levels that do not significantly impair basic cognitive processes or psychomotor performance.