Medical Cannabis and Behavior

Official title

Neurobehavioral Impacts of Medical Cannabis Use: An Observational Study

Overview

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.

Detailed description

This project was submitted to NIH in response to NOT-DA-22-003, Public Health Research on Cannabis. The overarching aim is to assess cognition, neural function, and SUD risk in a sample of patients treated with medical cannabis products in Minnesota (n=120) as compared to non-cannabis using controls (n=60) and to differentiate outcomes based on prescribed doses and blood concentrations of THC versus CBD as objective measures of drug exposure. Patients will be aged 35-65 and qualified for medicinal cannabis treatment in Minnesota due to diagnoses of chronic pain. While deficits in learning, memory and executive functions are reliably observed in young adult recreational cannabis users, it is unclear whether similar impairments characterize individuals who use cannabis for medical reasons, whether adults may be uniquely vulnerable to cannabis-related impairments or if, in fact, use in this age group might be neuroprotective. There are very few published studies of medical cannabis users that comprehensively focus on neurobehavioral outcomes even though at least 5 million people are registered for medical cannabis treatment in the United States. The current study will address this gap through a pre-post assessment of users as compared to matched controls (pain patients who do not use cannabis). Participants will be recruited through posted advertisements and through dispensaries via a collaboration with a local supplier of medical cannabis. They will complete a comprehensive pre-treatment behavioral assessment as well as multimodal brain MRI assessments. All measures will be repeated after four months of treatment. Participants will be interviewed monthly by phone in the interval between visits to assess treatment adherence, pain levels, quality of life, and substance use. Blood cannabinoid levels will be measured at baseline and after four months and will be correlated with behavioral and neural outcomes. The three aims are (1) To assess impacts of medical cannabis compounds on cognition and behavior in otherwise cannabis-naive adults to determine whether impairments that characterize younger users are evident after the onset of medical cannabis use; the investigation will also measure treatment-related changes in pain using well-validated measures. (2) To similarly assess the impacts of medical cannabis compounds on white matter microstructure, functional brain activity and functional connectivity using diffusion-weighted scans, task-based fMRI, and measures of resting state connectivity; (3) To differential change over time in these outcomes as a function of (a) exposure to distinct cannabinoids (THC vs. CBD) as assessed through blood concentrations and (b) age. Sex as a biological variable will be assessed as a covariate of interest. Thus, this proposal will yield a rich dataset through which medical cannabis effects on adults' neurobehavioral function can be assessed and contrasted with the literature on non-medical users.

Interventions

• Behavioral Cognitive testing
  Participants will complete a cognitive testing battery that includes measures of attention, learning, memory, problem-solving and executive function.
• Behavioral Task-based fMRI measure of face-name and verbal learning
  Cognitive testing Participants will complete a cognitive battery that includes measures of attention, learning, memory, and executive function. Behavioral: Task-based fMRI measure of face-name and verbal learning. These tasks will assess cannabis effects on explicit associative learning and memory mediated by frontohippocampal networks. Participants memorize face-name or word pairs (encoding), then recall the names and word pairs after a delay. The first encoding block begins with a "MEMORIZE" c

Primary outcome measures

• Rey Auditory Verbal Learning Test [Time frame: Administered at baseline and after four months]
• Digit Span Task [Time frame: Administered at baseline and after four months]
• Verbal Fluency Task [Time frame: Administered at baseline and after four months]
• Spatial Span Task [Time frame: Administered at baseline and after four months]
• Grooved Pegboard Task [Time frame: Administered at baseline and after four months]
• CANTAB Spatial Paired Associates Learning Task [Time frame: Administered at baseline and after four months]
• CANTAB Stockings of Cambridge Task [Time frame: Administered at baseline and after four months]
• CANTAB Self-Ordered Search Task [Time frame: Assessed at baseline and after four months]
• Iowa Gambling Task (IGT) [Time frame: Assessed at baseline and after four months]
• Face-Name Learning Task. [Time frame: Administered at baseline and after four months]

Secondary outcome measures (4)

• Alcohol Use Disorders Identification Test (AUDIT) [Time frame: Baseline and monthly for four months thereafter]
• Brief Pain Inventory [Time frame: Baseline and monthly for four months thereafter]
• Beck Depression Inventory (BDI) [Time frame: Assessed at baseline and monthly for four months]
• UPPS-P Impulsive Behavior Scale [Time frame: Assessed at baseline and after four months]

Eligibility criteria

Inclusion criteria

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

• Be ages 30-75;
• 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;
• No history of daily cannabis use; limited cannabis product use (recreational or therapeutic) within the past three 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 30-75;
• 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;
• No history of daily cannabis use; cannabis use within the past three months limited to a few times.
• 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 criteria

• 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;

Criteria are shown verbatim from the registry (in English). Final eligibility is always assessed by the study center.

Healthy volunteers: No

Study design

Allocation

N/A

Model

Single group

Masking

Open label

Primary purpose

Basic science

Study locations

United States · 1 center

• University of Minnesota — Minneapolis

Identifiers

NCT: NCT06808048 · STUDY00011239 · R01DA059961

Primary sources (government registries)

• ClinicalTrials.gov (US NIH)

View this study on ClinicalTrials.gov ↗