Cannabis Observations on Brain Waves, Retrieval, and Attention: Experiment 3

This study investigates the impact of ∆9-tetrahydrocannabinol (THC) and cannabidiol (CBD) on recognition memory in healthy, regular cannabis users. Participants complete the same recognition memory task after self-administering one of two different strains of cannabis flower one day and while not intoxicated another day. Event-related potentials (ERPs) are measured via electroencephalogram (EEG) during the recognition memory task. Blood is collected to quantify THC and CBD exposure. Participants also complete self-report measures of medical history, sleep quality, subjective cognitive function, physical activity, psychological functioning, substance use, and acute drug effects.

Previous research has established cannabis's harmful cognitive impact, with particularly robust and consistent effects in the domain of episodic memory. However, prior work has not sufficiently considered that the memory effects of cannabis are the compound action of different cannabinoids, which vary in their pharmacology and effects. Specifically, CBD, a non-psychotomimetic component of cannabis (doesn't produce a "high"), is thought to have cognitively protective properties and may mitigate some of the harmful effects of THC. Further, few prior studies have tested the effects of high potency strains that are commonly available.

This study tests the effects of commercially available cannabis flower strains on recognition memory performance and ERPs that are related to different underlying memory processes in healthy, regular cannabis users. An episodic memory task is used to assess recognition memory, which asks participants to discriminate between previously studied and non-studied items using pictures as stimuli. Participants complete the same memory task while intoxicated one day and not intoxicated another day. A THC-dominant strain and a strain containing both THC and CBD are included in the study. Participants self-administer one of the two cannabis strains prior to memory encoding and retrieval.

Blood is collected to determine THC and CBD exposure, as well as to explore how genetic variation in genes related to cannabinoid metabolism, cannabis-related behavior, and neurocognitive function associate with memory function before and after cannabis use. Participants also complete self-report measures of medical history, sleep quality, subjective cognitive function, physical activity, psychological functioning, substance use, and acute drug effects.

Eligibility Criteria:
Inclusion Criteria:

1. Must be between the ages of 21 and 40 and provide informed consent;
2. Must be right-handed (Laterality Quotient \> 60 on Edinburgh Handedness Inventory - Short Form);
3. Must use cannabis at least 4 days during the month;
4. Must be a cannabis user for at least a year;
5. Must self-report not using other illicit recreational drugs (e.g., cocaine, benzodiazepines (non-prescription), opiates (non-prescription), MDMA, sedatives, or methamphetamine) in the past 30 days, during the Pre-Screening;
6. Must not test positive on a urine toxicology test for drugs of abuse at the Baseline appointment;
7. Must not be using psychotropic medications, however anti-depressant, non-benzodiazepine anti-anxiety, and ADHD medications are ok. ADHD medication users must be willing to abstain from ADHD medication use on appointment days;
8. Must not be a regular nicotine user (≤4 days per week; cigarette, E-cigs, or smokeless);
9. Must not have used caffeine or nicotine (cigarette, E-cigs, or smokeless) for 4 hours before each appointment;
10. Must have a breath alcohol level of 0 at Baseline appointment (to sign consent form);
11. Must not be actively seeking or in treatment for any substance use disorder;
12. Female subjects must not be or trying to become pregnant (as indicated by a pregnancy test administered at Baseline appointment);
13. Must not be in treatment for psychotic disorder or bipolar disorder; or have a history with these disorders;
14. Must not have any physical characteristics (e.g., thick hair, head size exceeding the limit of the net, dyed hair) or experience any technical difficulties during testing that result in a poor-quality EEG recording.