Implications of Inertia for Assessing Drug Control Policy: Why Upstream Interventions May Not Receive Due Credit

Abstract

An empirically-derived model of national drug initiation is combined with a compartment model of trends in illicit drug use parameterized for Australia. Numbers of initiates seem to oscillate over time but with fluctuations whose aptitude diminishes over time. Lags and interpersonal variation in drug use careers smooth those oscillations for measures of problem use and total drug-related social cost, so even abrupt changes in initiation barely ripple the trajectory of drug-related social cost. Hence, the benefits of interventions that successfully disrupt initiation may be “hidden in plain sight” by being spread broadly over time so that they leave only the faintest finger-print detectable by before-and-after comparison. Thus, the absence of clear drops in drug-related problems does not imply that an upstream ntervention such as prevention or supply disruption did not produce substantial social benefits. More generally, drug use and related problems are often perceived of as stubborn, even intractable. Some of that perception stems from real limitations in the effectiveness of drug-control interventions. However, inertia inherent in the evolution of drug use can make even cost-effective interventions appear weak (and detrimental interventions appear benign).