Trial Outcomes & Findings for Neural Mechanisms of Cannabinoid-impaired Decision-Making in Emerging Adults (NCT NCT03944954)

Forty young adults (N=40; n=20 per Experiment) aged 18-34 who report habitual cannabis use (20 or more days per month) or meet hazardous cannabis use criteria will complete the study. A 15% dropout rate is assumed. Subjects will be matched on sex, age and education. Enrollment will approximate the demographic proportions of Fayette County, KY. so we anticipate enrolling members mostly from those demographic categories.

Neural Mechanisms of Cannabinoid-impaired Decision-Making in Emerging Adults

In a Probabilistic Reinforcement Learning Choice (PRLC) task, two stimuli are presented and choosing either could result in a monetary reinforcer, but the reinforcement probabilities of the stimuli differ, and change throughout the task. Individuals attempt to optimize choices according to learned probabilities and track changing probabilities over time. PRLC performance allows mathematical modeling of trial-by-trial data under "real-world" uncertainty and yields computational parameters, such as the learning rate. Choice data were analyzed using a Rescorla-Wanger learning model with an alpha learning rate, beta inverse temperature, and perseveration global parameters. Model-derived learning rates are indicative of an individual's ability to learn from previous choice outcomes to update future decision-making. For this task, learning rates range from 0-1 with lower values indicative of more optimal learning.

A Visual Analogue Scale (VAS) was used to measure the acute subjective effects of THC at varying doses (0mg, 10mg, 30mg). Responses are made for VAS items along a 100-unit scale anchored on the extremes by "Not At All" (0) and "Extremely" (100) with a higher score meaning more of the effect. Participants were instructed to select "Not At All" (0) for all baseline (0HR) measures. Post-TMS administration (real or sham), participant self-reported their subjective "high" on the VAS with higher values indicating a more intense sensation of "high".

Elasticity of Demand was measured by the Cannabis Purchase Task (CPT) where participants are asked how many "hits" of cannabis they would consume at 16 different price points in ascending order ($0-$140). Higher elasticity values indicate a greater sensitivity to changing price points resulting in a reduced demand for "hits" of THC at increasing price points.

Working memory (WM), the ability to hold a finite amount of information for a set amount of time, is measured by the N-Back task. Here, participants were presented with a sequence of letters and must indicate when the letter currently being viewed matches the one from N steps earlier in the sequence. The load factor "N" is adjusted between 0, 1, and 2 to adjust the difficulty of the task (0-Back = no WM load, 1-Back = minimal WM load, 2-Back = greater WM load) where a higher score means better memory performance. Outcomes are reported as the Total Accuracy Percentage (Correct Choices/Total Choices) x 100%