Risk-sensitive foraging theory elucidates risky choices made by heroin addicts

The behavioral process of risk-sensitive foraging (RSF) specifies that the level of satiation or deprivation determines choice between a constant and variable quantity of food. Specifically, RSF stipulates that organisms experiencing satiation and deprivation prefer constant (risk-averse) and variable (risk-prone) choices, respectively. The relevance of this behavioral process to risky choices of opioid-dependent patients is examined in this study.

Thirty adult opioid-dependent out-patients made hypothetical choices between constant and variable heroin sources with equivalent means. Preferences for constant (e.g. three bags of heroin) and variable heroin sources (e.g. on average produces three bags of heroin, but vary from one to five bags of heroin on any instance) were assessed using questionnaires that manipulated the amount, delay to receipt and drug potency of heroin across approximately 20 levels. Subjects made choices between constant and variable options after hearing scripts describing the signs and symptoms of opioid satiation and opioid deprivation.

Consistent with the prediction of RSF, subjects purchased significantly more hypothetical heroin from a variable source when exposed to an opioid-deprived script than an opioid-satiated script. This pattern was observed across manipulations of heroin amount, delay to receipt of heroin and heroin potency. Selection of the variable option increased as a function of magnitude under the deprived conditions. The selection of the variable option generally did not increase as a function of magnitude under the satiated conditions except when delay to heroin delivery increased. As delay increased, selection of the variable option increased under the satiated script, but at a lower level observed with the deprived script.

These data suggest that risky choices of heroin-dependent individuals can be understood and predicted with the application of RSF theory. This research suggests that an evolutionarily old behavioral process may contribute to the risky behavior of the drug-dependent.