Substance-dependent individuals (SDIs) often show neurocognitive deficits in decision-
making, such that their choices are biased toward the greatest immediate reward rather than
the optimal future outcome. However, studies of SDIs are often hampered by two significant
methodological challenges: polysubstance dependence and comorbid conditions, which are
independently associated with neurocognitive impairments. We addressed these
methodological challenges by testing heroin addicts in Bulgaria, where heroin addiction is …