Alcohol and anxiety: ethopharmacological approaches

1. Anxiety reduction may be a mechanism in many of the behavioral problems associated with alcohol intake, including abuse, addiction, aggression, and impulsivity. 2. New "ethoexperimental" models of anxiety measure natural antipredator defensive behaviors. These include flight, freezing, and defensive threat and attack to discrete, present, threat stimuli; a pattern of risk assessment behaviors to potential threat; proximic avoidance and inhibition of nondefensive behaviors to both present and potential threat; and antipredator alarm vocalizations in a social situation when concealment is possible. 3. Alcohol reduces freezing, behavioral inhibition, and proximic avoidance. It increases risk assessment from a freezing baseline and decreases it from a movement (risk assessment) baseline. It has a biphasic effect on defensive attack, increasing it at low doses, but decreasing it at high doses. Alcohol has little or no effect on flight, defensive threat, and antipredator ultrasound. 4. The effects of alcohol on behavioral inhibition, proximic avoidance, and risk assessment from either a freezing or a movement baseline are identical to those of the classic anxiolytic, diazepam. However, alcohol appears to impact several defensive behaviors not influenced by diazepam. 5. These results provide considerable support for an anxiolytic interpretation of alcohol effects, but suggest that alcohol may have additional effects than those on anxiety mechanisms.