Acute effects of alprazolam on risky decision making in humans.

Rationale: GABA-A receptor ligands, including benzodiapines, may induce disinhibitory effects that increase the probability of risky decision making. To date, few laboratory studies have examined the acute, dose-related effects of benzodiazepines on human risk-taking behavior. Recent data indicate that in the United States alprazolam is the benzodiazepine most frequently misused for recreational purposes.

Objectives: The present study was designed to demonstrate a dose-response relationship between acute alprazolam administration and human risk taking. Furthermore, this investigation sought to examine: (1) the behavioral mechanisms that may be involved in changes in the probability of risky decision making related to alprazolam administration and (2) risk seeking-related personality variables that may predict drug effects on risk taking.

Methods: Using a laboratory measure of risk taking designed to address acute drug effects, 16 adults were administered placebo, 0.5, 1.0, and 2.0 mg alprazolam in a within-subject repeated-measures design. The risk-taking task presented subjects with a choice between two response options operationally defined as risky and nonrisky. Data analyses examined subjective effects, response rates, distribution of choices between the risky and nonrisky option, trial-by-trial response probabilities, and personality correlates related to drug effects at the 2.0-mg dose.

Results: Alprazolam administration produced dose-related changes in subjective effects, response rates, and, most importantly, dose-dependently increased selection of the risky response option. The 2.0-mg dose increased the probability of making consecutive risky responses following a gain on the risky response option. Increases at 2.0 mg were related to a combination of personality scales that included high venturesomeness and novelty seeking and low harm avoidance.

Conclusions: Alprazolam administration produced increases in human risk taking under laboratory conditions. In union with previous studies, the observed shift in trial-by-trial response probabilities suggests that sensitivity to consequences (e.g., oversensitivity to recent rewards) may be an important mechanism in the psychopharmacology of risky decision making. Additionally, risk-seeking personality traits may be predictive of acute drug effects on risk-taking behavior.