Medical Cannabis and Behavior
Neurobehavioral Impacts of Medical Cannabis Use: An Observational Study
University of Minnesota
180 participants
Jun 18, 2025
INTERVENTIONAL
Summary
This study will assess cognition, neural function, and drug exposure in chronic pain patients who have been prescribed medical cannabis and will differentiate outcomes based on use of specific CBD-dominant versus THC-dominant treatment products. This longitudinal study will recruit medical cannabis users from local dispensaries. Each participant will complete a baseline assessment prior to the start of medical cannabis use, monthly phone calls to assess treatment adherence, and a four-month follow- up assessment. The aims of this project are: Aim 1. To assess impacts of medical cannabis compounds on executive functions, learning and memory in adults to determine whether cognitive impairments are evident after the onset of cannabis use; Aim 2. To assess the impacts of medical cannabis compounds on white matter microstructure, functional brain activity and functional connectivity; Aim 3. To differentiate change over four months in these outcomes as a function of (a) age and (b) pre-to-post-treatment changes in blood levels of cannabinoid compounds.
Eligibility
Inclusion Criteria25
- Medical cannabis users (n=120) will be required to
- Be ages 35-65;
- Be qualified for a medical cannabis prescription based only on a diagnosis of chronic pain; note that individuals can, in theory, utilize medical cannabis for more than one qualifying condition. People with orthopedic pain will be prioritized.
- Have normal or corrected-to-normal vision and hearing;
- Be free of current and past DSM-V-defined substance use disorders; have < 5 lifetime recreational uses of illicit drugs.
- Have limited daily exposure to nicotine (e.g., no daily smokers/vapers; use of nicotine products fewer than 5 occasions weekly);
- Willing to abstain from alcohol, nicotine, and other (non-treatment) drugs for 24 hours prior to study. Abstinence will be verified by breathalyzer and urine drug screening; must not test positive on breathalyzer and urine drug screenings for any nonprescribed psychoactive substance or for cannabis (at baseline);
- Must be right handed as assessed by the Edinburgh Handedness Inventory;
- Lifetime use of cannabis < 15 times; no cannabis product use (recreational or therapeutic) within the past six months;
- Able to schedule and complete a multi-hour single session protocol;
- Have sufficient manual mobility to be able to complete computerized neurocognitive assessments;
- Able to communicate with the researchers by phone during the four month pre-post assessment interval
- Pain patients who are not using medical cannabis (n=60) will be required to:
- Be ages 35-65;
- Suffer from a chronic pain condition that could qualify them for medical cannabis; People with orthopedic pain will be prioritized.
- Have normal or corrected-to-normal vision and hearing;
- Be free of current and past DSM-V-defined substance use disorders; have < 5 lifetime recreational uses of illicit drugs.
- Have limited daily exposure to nicotine (e.g., no daily smokers/vapers; use of nicotine products fewer than 5 occasions weekly);
- Willing to abstain from alcohol, nicotine, and other (non-treatment) drugs for 24 hours prior to study. Abstinence will be verified by breathalyzer and urine drug screening; must not test positive on breathalyzer and urine drug screenings for any non- prescribed psychoactive substance or for cannabis (at baseline);
- Must be right handed as assessed by the Edinburgh Handedness Inventory;
- Lifetime use of cannabis < 15 times; no cannabis product use (recreational or therapeutic) within the past six months;
- Able to schedule and complete a multi-hour single session protocol;
- Have sufficient manual mobility to be able to complete computerized neurocognitive assessments;
- Able to communicate with the researchers by phone during the four month pre-post assessment interval Within both groups, concomitant opioid use will be allowed as will other prescribed treatments. Controls will be matched to the cannabis group on age, sex, socioeconomic status (SES), type of pain condition (orthopedic pain will be targeted) and comorbid opioid use.
- All potential participants must indicate at the baseline enrollment that they have no immediate plans to relocate from the Twin Cities metro area (e.g., must be willing and able to participate in longitudinal assessment for a four-month period).
Exclusion Criteria5
- Cannot have a degenerative neurological condition or a neurological condition that impacts brain function (e.g., epilepsy);
- No contraindications to MRI scanning;
- No lifetime history of severe DSM-V psychopathology (psychotic disorders, bipolar disorder); if currently treated mood for anxiety disorders, must be stable;
- No current pregnancy or pregnancy within the prior 3 months; cannot be lactating;
- No cannabis product use (recreational or therapeutic) within the past six months;
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Interventions
Participants will complete a cognitive testing battery that includes measures of attention, learning, memory, problem-solving and executive function.
All participants will complete a task-based fMRI measure of inhibitory control. This Go/No-Go task provides a contrast of BOLD signals when response conflict is low (execution of motor responses on frequent Go trials) vs high (inhibiting the prepotent response on infrequent NoGo trials). It will provide an assessment of the effects of cannabis use on the frontostriatal implicit motor learning and cognitive control systems. Participants view shapes and press a button quickly (Go trials) to every shape except circles and squares (NoGo Trials). To increase response prepotency, Go trials are frequent (75%). Button presses must be rapid to be considered correct. The task uses an event-related design with each stimulus presented for 600 ms, followed by a 1.0-4.5 second jittered ISI during which a white fixation crosshair is displayed. Trial type is pseudo-randomized with the constraint of equal frequencies of consecutive Go trials (2, 3, or 4) between NoGo trials.
This task is ideally suited to assess cannabis effects on explicit associative learning and memory as mediated by frontohippocampal networks. Participants memorize names corresponding to faces (encoding phase), and then recall the names after a short delay. The first encoding block begins with a 2-second cue ("MEMORIZE") followed by 5 face-name pairs, each shown for 4 seconds; participants press a button when they encode each face-name pair. A distractor block follows. Next, a retrieval block begins with a cue to "RECALL" followed by presentations of each of the same 5 faces, now paired with "???" (i.e., prompting recall of previously paired names), with a 4 second stimulus duration and no ISI. On recall trials, participants press a button to indicate that they have recalled the name for the displayed face. Participants engage in silent uncued recall of face-name pairs. Immediately following the scan, participants are tested for accuracy of name retrieval.
Locations(1)
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NCT06808048