Comorbid depression, antisocial personality, and substance dependence: Relationship with delay discounting

Within the field of addiction, as many as four-fifths of individuals in treatment for substance use disorder have co-existing lifetime psychopathology and as high as two-thirds have current psychopathology. Among substance-dependent individuals, excessive delay discounting is pervasive. Despite evidence of excessive discounting across substance use disorders, few studies have investigated the impact of co-occurring psychopathologies and SUD on delay discounting.

We compared delay discounting in currently abstaining substance users with (a) SUD (n=166), (b) SUD and managed major depressive disorder (MDD; n=44), (c) SUD and antisocial personality disorder (APD; n=35), (d) SUD and managed MDD and APD (n=22) and (e) no SUD or co-occurring psychopathology (n=60).

All groups with SUD discounted future delayed rewards significantly more than healthy controls (p<0.001 in each case, d=0.686, 0.835, 1.098 and 1.650, respective to groups a-d above). Individuals with both APD and SUD and individuals with MDD, APD, and SUD discounted future rewards significantly more than substance users without comorbid psychopathology (p=0.029, d=0.412 and p<0.001, d=0.964, respectively).

Overall, individuals with multiple psychopathologies in addition to substance use have exacerbated deficits in discounting of the future, above and beyond that observed in substance use alone. Increased discounting in combined substance and psychopathology profiles suggest a greater chance of treatment failure and therefore may necessitate individualized treatment using adjunctive interventions to achieve better treatment outcomes.