Developing a Mobile Method to Measure THC-induced Impairment (AIS)

Marijuana use, for both recreational and therapeutic purposes, is becoming increasingly common as states remove restrictions on use. The increased use raises new concern about the safety of this drug, including its ability to impair basic cognitive and psychomotor tasks, and whether the users are aware of their impairment. We propose to design a simple performance test that users can use in the field, using a cell phone, to assess their level of impairment relative to their own drug-free state. In this preliminary study, we will compare participants' simple task performance after a known dose of delta-9-tetrahydrocannabinol (THC), or placebo, administered under double-blind conditions. In our app the participants will be asked to gauge their own perceived level of impairment (as determined by self-ratings and judgments of impairment) as well as their actual impairment (as gauged by the app), providing important feedback and training about their ability to detect impairment.

THC (Marinol® [dronabinol]; Solvay Pharmaceuticals) will be orally administered in doses of 7.5 mg and 15 mg, in opaque capsules with dextrose filler. Placebo capsules contain only dextrose. These doses of THC are known to produce performance impairments as well as subjective intoxication (Broyd et al, 2016; Hartman and Huestis, 2013).

In this reaction time task, the user is asked to shake the device in response to a visual clue on the device's screen. The user makes three attempts, in which he or she must shake or move the device with an acceleration that is greater than the value of the thresholdAcceleration property within the given time. The task finishes when the user successfully completes the attempts as instructed in the task. Data collected by this task is in the form of ORKReactionTimeResult objects. Each of these objects contain a timestamp representing the delivery of the stimulus and an ORKFileResult object that references the motion data collected during an attempt.

Inclusion Criteria: 18-35 years old, males and females (N=44; 36 completers; 18 men, 18 women) BMI 19-26 High school education, fluent in English Experienced non-daily marijuana users Exclusion Criteria: Current drug/alcohol abuse or dependence Past year drug/alcohol dependence Diagnosis with drug treatment for psychosis/bipolar/schizophrenia Past year major depression Panic/anxiety attacks in past 2 months PTSD ADHD Cardiovascular illness, high blood pressure, abnormal EKG Current medications Pregnant or planning to become pregnant