Cannabis (smoked flower)
Self directed use (ad libitum)
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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.
Locally preserved from ClinicalTrials.govOpen ClinicalTrials.govlast source update 2026-07-01
What this record can show
This locally preserved record separates the registered protocol from source-reported registry results. Neither is a treatment recommendation.
Registry facts
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.
Linked local records
Local links use governed condition terms or exact source-reported intervention names. They are navigation candidates, not efficacy claims.
Interventions
Self directed use (ad libitum)
Eligibility
Community sample of healthy, regular cannabis users in the Boulder/Denver areas.
primary outcomes
Time frame: Intoxicated session and not-intoxicated session (about 1 week)
The FN400 event-related potential (ERP) old/new effect will be measured using electroencephalography (EEG) during a recognition memory test. The FN400 reflects familiarity-based memory retrieval and is defined as the mean ERP amplitude difference between correctly recognized previously presented items ("hits") and correctly rejected novel items ("correct rejections") at mid-frontal electrode sites during the 300-500ms post-stimulus interval.
Time frame: Intoxicated session and not-intoxicated session (about 1 week)
The parietal ERP old/new effect will be measured using EEG during a recognition memory test. The parietal old/new effect reflects recollection-based memory retrieval and is defined as the mean ERP amplitude difference between hits and correct rejections at parietal electrode sites during the 500-800ms post-stimulus interval.
Time frame: Intoxicated session and not-intoxicated session (about 1 week)
Behavioral accuracy during recognition memory test will be assessed by the number of hits and correct rejections made during memory recall. Retrieval memory accuracy will be compared between intoxicated and not-intoxicated sessions.
Time frame: Intoxicated session and not-intoxicated session (about 1 week)
Memory performance will be assessed via reaction time, measured by a photocell during recognition memory testing and concurrent EEG. During the recall phase, a light indicator will appear in the bottom-right corner of the stimulus screen when a prompted image is presented, activating the photocell. This indicator disappears once the participant responds. The interval between stimulus onset and the participant's "new" or "old" response is used as the reaction time measure for both intoxicated and non-intoxicated sessions. Retrieval memory performance will be compared between intoxicated and not-intoxicated sessions.
secondary outcomes
Time frame: During a single non-intoxicated laboratory session and immediately before and immediately after acute cannabis use during a single intoxicated laboratory session
The PANAS is a Self-report measurement of positive and negative affect that will be administered at all times of the Mobile sessions: the pre-use and post-use timepoints of the intoxicated session, well as the not-intoxicated session. The PANAS will be used twice at the intoxicated session to measure changes in mood before and after cannabis use. The survey presents a 20-item scale from 1 (very slightly or not at all) to 5 (extremely), with a higher score on the positive affect scale indicating higher positive affect and a higher score on the negative affect scale indicating higher negative affect.
Time frame: During a single non-intoxicated laboratory session and immediately before and immediately after acute cannabis use during a single intoxicated laboratory session
The DEQ is a 5-item visual analogue scale that measures acute drug effects, with prevalent use across numerous drug studies. Specifically, the questionnaire measures strength of the effects of cannabis as well as the desirability of the effects. Participants answer questions on a range from 0 - 100, with higher values for each item indicating greater drug effect or desire. The specific items related to drug "liking" and "wanting more" have been associated with harmful drug use. Participants will be administered the DEQ at all time points of the Mobile sessions to assess differences following intoxication.
Time frame: During a single non-intoxicated laboratory session and immediately before and immediately after acute cannabis use during a single intoxicated laboratory session
The ARCI-M is a self-report measure of subjective effects of marijuana in addition to drug-induced euphoria, stimulant-like effects, intellectual efficiency and energy, sedation, dysphoria, and other somatic effects. This is a 12 item true-false task, in which higher (true) scores indicate greater intoxication. Participants will be administered the ARCI-M at all time points of the Mobile sessions to assess differences following intoxication.
Time frame: During a single non-intoxicated laboratory session and immediately before and immediately after acute cannabis use during a single intoxicated laboratory session
The Marijuana Craving Questionnaire is a self-report measure of marijuana craving that will be administered at all time points during the Mobile sessions. Participants complete 8 questions ranging from 0 - 10, with a higher score indicating greater cannabis craving and somatic symptoms. The primary focus of this questionnaire will be the effect of intoxication on reporting.
Time frame: During a single non-intoxicated laboratory session and immediately before and immediately after acute cannabis use during a single intoxicated laboratory session
The POMS is a self-report measure of mood. Participants complete 27 mood-related items ranging from 0 - 4, with higher scores indicating greater levels of specific mood states. The POMS will be administered at all time points of the Mobile sessions, in order to measure changes in mood before and after intoxication.
Time frame: During a single non-intoxicated laboratory session and immediately before and immediately after acute cannabis use during a single intoxicated laboratory session
The Alcohol Craving Questionnaire is a self-report measure of alcohol craving. This is a 2-item scale with each item ranging 0 - 10, with higher scores indicating greater alcohol craving. The ACQ is used at all time points of the Mobile sessions.
Time frame: During a single non-intoxicated laboratory session and immediately before and immediately after acute cannabis use during a single intoxicated laboratory session
The SAPC-B is a self-report measure of paranoia. Participants complete 5 items each ranging from 0 - 10, with higher scores indicating greater feelings of paranoia. The SAPC-B is administered at all time points of the Mobile sessions to assess changes in paranoia after intoxication.
Time frame: Baseline, intoxicated session, and not-intoxicated session (about 3 weeks total over all three sessions)
Participants use cannabis ad-libitum. Therefore, blood levels of THC and CBD will be used to quantify dosage and compared across the not-intoxicated, pre-use and post-use time points of the Mobile sessions. This further allows for a direct test of whether any differences in outcomes for participants randomly assigned to the -THC/+CBD strain are due to an increase in CBD or a decrease in THC as compared to their baseline.
other outcomes
Time frame: Baseline, intoxicated session, and not-intoxicated session (about 3 weeks total over all three sessions)
DNA will be extracted from 3.0 ml of blood from the baseline session. After extraction, DNA will be quantified and stored at -80° for analysis. DNA will be collected to look at differences in epigenetic and single nucleotide polymorphisms (SNPs) in participants. Due to the rapidly changing landscape of genetic science, the DNA samples collected in this study are primarily for bio-banking purposes. The analysis of these genetic samples is expected to be performed at a future date to contribute to the current study and/or future studies. Participants will be allowed to opt out of storage of genetic samples for future research.
Time frame: Baseline, intoxicated session, and not-intoxicated session (about 3 weeks total over all three sessions)
Baseline measurement of sleep disturbance, assessing participant's quality and patterns of sleep over the last seven days. Participants complete 4 items, for a total scale score from 4 - 20, with higher scores indicating more sleep disturbance.
Time frame: Baseline, intoxicated session, and not-intoxicated session (about 3 weeks total over all three sessions)
Baseline assessment of affective symptoms. Participants complete the Depression, Anxiety, and Stress Scale-21 (DASS-21), a 21-item measure consisting of three 7-item subscales assessing depression, anxiety, and stress/tension. Higher scores indicate greater symptom severity within each domain. Acute drug-effect measures will be collected at each study session, including before and after participants self-administer their assigned cannabis strain during mobile laboratory sessions.
Time frame: Baseline, intoxicated session, and not-intoxicated session (about 3 weeks total over all three sessions)
The TLFB is used to assess daily substance use for 30 days prior to the Baseline Appointment and 3-7 days prior to the later sessions. Our modified TLFB procedure will estimate both frequency of marijuana use and amount used per day, using visual stimuli as well as the method of administration.
Publications
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