Alcohol and anxiety: effects on offensive and defensive aggression

Inconsistencies in the effects of alcohol on aggression in rodent models suggest that this effect is mediated through some other factor that is differentially involved in the various tests. The patterning of alcohol enhancement of aggression suggests that this may be most apparent in tests in which defensiveness or anxiety act to reduce aggression. Thus, an understanding of the relationship between alcohol and aggression may also involve determination of alcohol effects on anxiety. New ethoexperimental models of anxiety in rodents involve the measurement of a range of defensive behaviors to approaching, contacting predators, or to situations associated with (absent) predators. A Fear/Defense Test Battery, measuring the former, showed little, and inconsistent, response to traditional (benzodiazepine) or nontraditional (5-HT1A agonist) anxiolytics. However, an Anxiety/Defense Test Battery, measuring the latter, produced an "anxiolytic profile" of changes seen consistently to both traditional and nontraditional anxiolytics, but not to nonanxiolytic drugs. Alcohol (0.6 and 1.2 g/kg) altered the four behaviors of the "anxiolytic profile" in a manner consistent with the effects of diazepam (2.0 and 4.0 mg/kg), indicating that it is also anxiolytic. The consistency of alcohol and diazepam effects on anxiety provide a possible mechanism for their somewhat similar effects on aggression. However, alcohol at nonsedative doses, but not diazepam, additionally enhances defensive attack. Although defensive attack is behaviorally and neurally different from offensive aggression, the two are not separated in analyses of human "aggression," suggesting that alcohol effects in the latter may also be mediated by changes in defensive attack.