Preprint: Altered subjective reward valuation among drug-deprived heavy marijuana users: Aversion to uncertainty

Heavy marijuana users who were deprived of the drug showed reduced valuation of uncertain rewards, especially when those rewards were objectively more valuable. This aversion to uncertainty increased with greater quantities of marijuana use. The findings suggest that marijuana use may produce decision-making vulnerabilities similar to those seen with other drugs of abuse, pointing to potential targets for intervention.

Study at a glance

Abstract

Marijuana is the most commonly used illicit drug in the United States and its use is rising. Nonetheless, scientific efforts to clarify the risk for addiction and other harm associated with marijuana use have been lacking. Maladaptive decision-making is a cardinal feature of addiction that is likely to emerge in heavy users. In particular, distorted subjective reward valuation related to homeostatic or allostatic processes has been implicated for many drugs of abuse. Selective changes in responses to uncertainty have been observed in response to intoxication and deprivation from various drugs of abuse. To assess for these potential neuroadaptive changes in reward valuation associated with marijuana deprivation, we examined the subjective value of uncertain and certain rewards among deprived and non-deprived heavy marijuana users in a behavioral economics decision-making task. Deprived users displayed reduced valuation of uncertain rewards, particularly when these rewards were more objectively valuable. This uncertainty aversion increased with increasing quantity of marijuana use. These results suggest comparable decision-making vulnerability from marijuana use as other drugs of abuse, and highlights targets for intervention.