Medical cannabis effects on thinking, memory, and brain activity

Neurobehavioral Impacts of Medical Cannabis Use: An Observational Study

This project will test whether CBD‑dominant versus THC‑dominant medical cannabis changes thinking, memory, and brain activity in adults aged 35–65 who use medical cannabis for chronic pain.

Quick facts

• Phase: Not applicable
• Study type: Interventional
• Enrollment: 180 (estimated)
• Ages: 35 Years to 65 Years
• Sex: All
• Sponsor: University of Minnesota (Academic / other)
• Locations: 1 site (Minneapolis, Minnesota)
• Trial ID: NCT06808048 on ClinicalTrials.gov

What this trial studies

This longitudinal, interventional project will enroll 120 adults with chronic pain who begin medical cannabis treatment and 60 matched pain controls who do not use cannabis, with baseline testing before cannabis use and a four‑month follow‑up. Participants will complete cognitive testing, task‑based fMRI (inhibitory control and face‑name learning), and blood sampling to measure THC and CBD concentrations, plus monthly phone calls to track adherence. The design compares pre-to-post changes in cognition and brain measures and links those changes to measured doses and blood pharmacokinetics of THC versus CBD. Exclusion criteria include current or past DSM‑V substance use disorders, heavy nicotine use, and failure to abstain from substances prior to testing.

Who should consider this trial

Good fit: Adults aged 35–65 in Minnesota with chronic pain who are qualified for medical cannabis treatment, willing to undergo MRI and cognitive testing, willing to abstain from alcohol/nicotine/other drugs for testing, and without current or past substance use disorders are ideal candidates.

Not a fit: People outside the 35–65 age range, those with past or current substance use disorders, daily smokers/vapers, long‑term regular cannabis users at baseline, or those unwilling to attend in‑person MRI visits are unlikely to benefit from participating.

Why it matters

Potential benefit: If successful, the findings could help patients and clinicians choose medical cannabis products and dosing with clearer information about possible effects on thinking, memory, and brain function.

How similar studies have performed: There are many studies showing cognitive effects of recreational cannabis in younger adults, but very few comprehensive longitudinal studies have tested neurobehavioral outcomes specifically in middle‑aged medical cannabis users, so this approach is relatively novel in that population.

Eligibility criteria

Inclusion Criteria:

* Medical cannabis users (n=120) will be required to

  1. Be ages 35-65;
  2. 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.
  3. Have normal or corrected-to-normal vision and hearing;
  4. Be free of current and past DSM-V-defined substance use disorders; have \< 5 lifetime recreational uses of illicit drugs.
  5. Have limited daily exposure to nicotine (e.g., no daily smokers/vapers; use of nicotine products fewer than 5 occasions weekly);
  6. 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);
  7. Must be right handed as assessed by the Edinburgh Handedness Inventory;
  8. Lifetime use of cannabis \< 15 times; no cannabis product use (recreational or therapeutic) within the past six months;
  9. Able to schedule and complete a multi-hour single session protocol;
  10. Have sufficient manual mobility to be able to complete computerized neurocognitive assessments;
  11. 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:

1. Be ages 35-65;
2. Suffer from a chronic pain condition that could qualify them for medical cannabis; People with orthopedic pain will be prioritized.
3. Have normal or corrected-to-normal vision and hearing;
4. Be free of current and past DSM-V-defined substance use disorders; have \< 5 lifetime recreational uses of illicit drugs.
5. Have limited daily exposure to nicotine (e.g., no daily smokers/vapers; use of nicotine products fewer than 5 occasions weekly);
6. 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);
7. Must be right handed as assessed by the Edinburgh Handedness Inventory;
8. Lifetime use of cannabis \< 15 times; no cannabis product use (recreational or therapeutic) within the past six months;
9. Able to schedule and complete a multi-hour single session protocol;
10. Have sufficient manual mobility to be able to complete computerized neurocognitive assessments;
11. 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 Criteria:

1. Cannot have a degenerative neurological condition or a neurological condition that impacts brain function (e.g., epilepsy);
2. No contraindications to MRI scanning;
3. No lifetime history of severe DSM-V psychopathology (psychotic disorders, bipolar disorder); if currently treated mood for anxiety disorders, must be stable;
4. No current pregnancy or pregnancy within the prior 3 months; cannot be lactating;
5. No cannabis product use (recreational or therapeutic) within the past six months;

Where this trial is running

Minneapolis, Minnesota

• University of Minnesota — Minneapolis, Minnesota, United States (Recruiting)

Study contacts

• Study coordinator: Monica Luciana, Ph.D.

Conditions Chronic Pain Patients; Medical Cannabis Users; cannabis; medical cannabis; brain MRI; pharmacokinetics