Impaired decision making related to working memory deficits in individuals with substance addictions

This study examined whether individuals with substance dependence (ISDs) show impairments in working memory and whether there is a relationship between their impairments in decision making as measured by the gambling task (GT) paradigm and working memory as measured by a delayed nonmatching to sample (DNMS) task. Using the GT, 11% of healthy control participants and 61% of ISDs opted for choices with high immediate gains in spite of higher future losses. For the ISDs and controls with equal GT impairments, the ISDs performed significantly lower than controls on the DNMS task. The nonimpaired ISDs on the GT also performed significantly worse than matched controls on the DNMS task. The DNMS task deficit in ISDs was across all delay times, suggesting the deficit may lie in the "executive" process of working memory, which supports earlier findings (E. M. Martin et al., 2003). The authors suggest that the prefrontal cortex hosts multiple distinct mechanisms of decision making and inhibitory control and that ISDs may be affected in any one or combination of them.