Time course of delta9-tetrahydrocannabinol inhibition of predatory aggression

Illicit drug use and violence

This chapter reviews evidence on the relationship between illicit drug use and violence, specifically cannabis, stimulant drugs, and opioids. It summarizes findings of systematic reviews of evidence on cannabis, stimulant drugs, and opioids. It also examines evidence from epidemiological studies of drug use among violent offenders and of violence among persons who use drugs, intervention studies, animal studies, human laboratory studies, and human neuroimaging studies. More studies have examined cannabis because of its higher prevalence of use. There is an association between cannabis use and violence, suggestive evidence of a dose-response relationship between the frequency of cannabis use and violence, and a stronger association in persons with psychoses. There is similar emerging evidence on stimulant use and violence, but evidence on opioids is very limited. There is limited and mixed evidence from intervention studies that reducing drug use reduces violence. Animal and human studies provide potential biological explanations for these associations. The association between cannabis use and violence is most consistent but limited by study heterogeneity and lack of control for potential confounders. It is unclear whether these associations are causal or reflect reverse causation or the effects of confounding.

Chronic delta 9-tetrahydrocannabinol administration and schedule-induced aggression

The effects of 0.5 mg/kg and 1.0 mg/kg of delta 9-tetrahydrocannabinol (delta 9-THC) on key-pecking maintained by a response-initiated fixed interval (FI) schedule of food presentation and schedule-induced aggression in the pigeon were studied. Initially, following the administration of delta 9-THC both the rate of key-pecking and attack responding were markedly reduced. Over sessions, tolerance developed to the suppressant effect on key-pecking, with the rate returning to the predrug level. The suppressing effect of delta 9-THC on the rate of attack remained at or near zero throughout the series of delta 9-THC injections.