Delay discounting and neurocognitive correlates among inner city adolescents with and without family history of substance use disorder

Abstract

Adolescents with a family history (FH+) of substance use disorder (SUD) are at a greater risk for SUD, suggested to be partly due to the transmission of behavioral impulsivity. We used a delay discounting task to compare impulsivity in decision-making and its associated brain functioning among FH+ and FH - minority adolescents. Participants chose between Smaller Sooner (SS) and Larger Later (LL) rewards. The SS was available immediately (Now trials) or in the future (Not-Now trials), allowing for greater differentiation between impulsive decisions. The FH+ group showed greater impatience by responding SS more frequently than the FH - group, only on the Now trials, and even when the relative reward differences (RRD) increased. Surprisingly, there were no differences in brain activity between the groups. Combined, the groups showed greater reward activity during the Now vs. Not-Now trials in medial prefrontal/anterior cingulate, posterior cingulate, precuneus, and inferior frontal gyrus (i.e., an immediacy effect). As the RRD increased activation in the reward network decreased, including the striatum, possibly reflecting easy decision-making. These results indicate that risk for SUD, seen behaviorally among FH+ adolescents, may not yet be associated with discernable brain changes, suggesting that early intervention has the potential to reduce this risk.

Keywords: Delay discounting; Family history; Substance use disorder; fMRI.

Fig. 1

Trial procedure of the delay discounting task in the delay and the acceleration conditions. In both conditions, participants were presented with a choice between a smaller amount of money available sooner (SS) and a larger amount available later (LL). Time of delivery for the SS was either today (Now trial) or in 2 weeks (Not-Now trials), and the time of delivery for the LL was either 2 or 4 weeks after the SS. In the delayed condition, the default option presented to the subject was the SS amount, whereas in the accelerated condition it was the LL amount. This was indicated by the green triangle under the choice option. Amounts offered ranged from $15 to $85.

Fig. 2

Proportion of LL choices for the Now and Not-Now trials for the FH+ and FH- groups. A. represents the choice proportions computed from the raw data. B. represents the estimated marginal mean probabilities based on the Bayesian model (with 95 % CIs).

Fig. 3

The proportion of LL choices as a function of the Relative Reward Differences (RRD) for the FH + and FH- groups. A. represents the choice proportions computed from the raw data. B. represents the estimated marginal mean probabilities based on the Bayesian model (with 95 % CIs).

Fig. 4

Group random effects for the Now vs. Not-Now trials for FH- and FH+ groups combined (N=102) in the option-based analysis (GLM1). A. Maps are threshold at p < 0.05 FPR corrected determined by a p-unc<0.001 at the voxel level and cluster size threshold of 218. B. The beta coefficients from the group random-effect analysis done on the combined groups shown in A. Data are shown for the peak value of the (sub) cluster comparing the Now and the Not- Now trials. IFG, inferior frontal gyrus; Pcu, precuneus; PCC, posterior cingulate cortex; ACC, anterior cingulate cortex; mPFC, medial prefrontal cortex.

Fig. 5

Group random effects for SS choices only, during the Now vs. Not-Now trials, for FH- and FH + groups (N=89) combined in the choice-based analysis (GLM2). Maps are threshold at p < 0.05 FPR corrected determined by a p-unc<0.001 at cluster size threshold of 181. IFG, inferior frontal gyrus; PreCG, precentral gyrus; Pcu, precuneus; PCC, posteriro cingulate cortex.

Fig. 6

Increasing negative modulation of BOLD activity by the Relative Reward Differences (RRD) of the group random-effects for all trials for combined (N=102) FH- and FH + groups (GLM1). Maps are threshold at p-unc<0.005 at the voxel level and cluster size threshold of 50. ITG, inferior temporal gyrus; VS, ventral striatum; IFG, inferior frontal gyrus; Pcu, precuneus; SMG, supramarginal gyrus.