Trajectories of Impulsivity in Opioid Use Disorder Treatment: A Longitudinal Study of Temporal Discounting and its Dynamic Relation to Drug Use and Treatment Efficacy Abstract

abstract

  • Background: Impulsivity is a core feature of substance usedisorders. Temporal discounting (TD) paradigms provide amodel-based approach to studying the dynamics of impulsivedecision-making as individuals with substance usedisorder undergo treatment. Here, we examine how TDchanges as opioid use disorder (OUD) subjects stabilize onmaintenance therapy and we assess how TD is predicted by(or is predictive of) relevant clinical outcomes such as illicitdrug use, treatment adherence and clinical states like craving.Methods: Individuals initiating medication-assisted treatmentfor OUD were assessed weekly then bi-weekly (for upto seven months) on a simple TD task. For each session, (1)we derived a computational subject-specific parameter forthe TD rate as well as a model-free measure: the proportionof immediate rewards chosen; (2) we monitored illicit druguse through randomly administered weekly urine toxicologyand direct self-report; (3) we established their level ofadherence to their individual treatment plan as well as theircurrent medication dose; and (4) we scored their currentlevels of craving, withdrawal symptoms and state anxiety.A group of demographically matched drug-free communitycontrols (CC) were similarly assessed repeatedly in order toestablish the test-retest reliability of our measurement anddiscard effects of practice and repetition.In addition, eligible subjects from both groups completed thetasks while we acquired functional magnetic resonanceimaging (MRI) data in two sessions: one at the beginningof the study and the other 8-12 weeks later. During thisinterval, subjects continued their regular assessments outsideof the scanner.Results: As previously reported, OUD patients havesignificantly higher discount rates compared to controlsbut in our demographically matched groups the differenceappears to be smaller than previously reported. Our resultsindicate that TD measurements have high test-retestreliability. While stable in our control group, in OUDpatients the TD rates are a dynamic function of time intreatment. Interestingly, TD rates also correlate with illicitdrug use events, peaking around the time that these occur.Moreover, the individual trajectory of TD leading up to theselapse events correlates with the degree of overall use duringour follow up, suggesting that the course of a patient'simpulsivity might be predictive of their relative success atmaintaining abstinence during treatment.Conclusions: We conclude that TD, when assessed repeatedlyover the course of treatment, could be used as abehavioral signature of a patient's clinical evolution andpotentially serve as a useful predictor of prognosis andtreatment adherence for OUD. Our TD task is easy toautomate and administer and therefore lends itself to use inlarger clinical studies and might be useful to incorporate intothe monitoring of these patients' progression. Our ongoingefforts focus on the investigation of the neural substrate(s) ofthe observed change in TD with treatment for OUD. We areexploring how the activity of regions involved in thecomputations necessary for impulsive decision-making (i.e.the ventromedial prefrontal cortex, ventral striatum andposterior cingulate cortex) contributes to treatment efficacy

publication date

  • 2016/12/1

edition

  • 41

keywords

  • clinical
  • oud
  • rates
  • treatment

International Standard Serial Number (ISSN)

  • 0893-133X

start page

  • S116

end page

  • S288