Discounting of delayed rewards and executive dysfunction in individuals infected with hepatitis C

Abstract

Objective: Determine whether adults with hepatitis C (HCV), regardless of substance use disorder, are more likely to discount delayed rewards than adults without hepatitis C, and explore the relationship between delay discounting and neuropsychological functioning.

Methods: Procedures included clinical interviews, neuropsychological testing, and a delay discounting task.

Results: Regardless of substance abuse history, adults with hepatitis C were significantly more likely to choose smaller immediate rewards over larger delayed rewards. Delay discounting correlated with performance on executive functioning tasks.

Conclusions: Increased discounting is associated with broad executive dysfunction, suggesting that HCV-associated executive dysfunction may lead to altered decision-making style.

Figure 1. Delay Discounting Task – Example Item

Subjects are asked: “At this moment, which would you prefer?”

Figure 2. Average discounting function by study group

Note: Performance on the Delay Discounting Task (DDT) is summarized as the function that best fits the mean ln(K) (natural logarithm of K) values by group. This function is termed the indifference curve and is represented as $I=\frac{100}{(1+K\cdot t)}$ where I represents the value of the immediate reward, t represents the delay time, and K is a constant that characterizes the degree of discounting. Points depicted above are the median indifference points (the immediate monetary value at which a participant switches preferences from the larger delayed reward to the smaller immediate reward) for a given delay period, and the bars represent the standard error. HCV = hepatitis C. SUD = history of substance use disorder, currently in remission.