The neuropsychological profile of pathological gambling tells a more complex story. Robust impairments have also been observed in studies that used the delay-discounting procedure, where participants choose between small rewards available immediately, or larger rewards available at some point in the future. Steeper delay-discounting is reported in pathological gamblers (Dixon et al., 2003; Petry, 2001; Petry and Casarella, 1999b). Petry (2001) also examined the issue of substance misuse co-morbidity, by comparing groups with pathological gambling and substance-use disorders, pathological gambling alone, and controls. Steeper discounting of future rewards was observed in both groups with pathological gambling, but there was an additive effect of substance abuse, with the steepest rate in the group with both gambling and substance abuse problems.
