Polysubstance dependent patients display a more utilitarian profile in moral decision-making than alcohol-dependent patients, depressive patients and controls.

Background: Addiction has been shown to be associated with the endorsement of utilitarian moral judgments. Ventro-medial prefrontal cortex (VMPFC) dysfunction may explain these findings.

Methods: 100 subjects were recruited: 25 polysubstance dependent patients, 25 alcohol dependent patients, 25 patients with major depressive disorders, and 25 normal controls. Subjects were assessed with a battery of 24 moral dilemmas: 8 impersonal dilemmas (no physical contact involved); 8 personal pareto (direct action that does not make the harmed individual worse off) and 8 personal non-pareto (direct action that does make the harmed individual worse off). The Iowa Gambling Task was used to document a possible connection between VMPFC dysfunction and responses to the moral dilemmas.

Results: Polysubstance dependent patients endorsed more utilitarian choices than controls on all types of dilemmas and more than depressed patients on impersonal and personal pareto dilemmas. Alcohol dependent patients had intermediate results between polysubstance dependent patients and controls but these differences were not significant. All patients showed significantly poorer performance compared to controls on the Iowa Gambling Task, but there was no significant association between Iowa Gambling Tasks scores and moral dilemma choices.

Conclusion: Polysubstance dependent patients made more utilitarian choices when responding to moral dilemmas than depressed patients and normal controls, while alcoholic patients showed intermediate results. The absence of correlation between performance on the Iowa Gambling Task and the number of more utilitarian choices indicates that moral dilemma and decision making under uncertainty tap into separate mechanisms.