All participants will be healthy volunteers and all procedures will be completed for research purposes only. Two groups will be recruited, females who use cannabis (marijuana, MJ), and female who do not use cannabis (controls). Female MJ users will be enrolled in a protocol that includes an outpatient drug administration session and a 4-day/3-night inpatient stay on the Johns Hopkins Bayview Clinical Research Unit (CRU). During outpatient visits, MJ users will have an MRI, and complete MJ self-administration and cognitive performance sessions. MJ users will then reside on the CRU,and complete MJ abstinence, and self-report instruments for withdrawal discomfort. A positron emission tomography (PET) scan of brain cannabinoid type 1 receptors will also be completed. Non-users will complete MRI, PET imaging and cognitive testing under an outpatient protocol (no MJ administration).
The primary goals of this project are to examine whether use of cannabis alters brain cannabinoid type 1 receptor (CB1R) availability in females, and if severity of cannabis withdrawal is correlated with CB1 receptor availability. CB1R are widely distributed in the human brain and can be quantified using PET imaging with the radiotracer 11C-OMAR (Carbon-11-OMAR). The effects MJ use on brain CB1R have not been studied in females. The current study will enroll 10 female MJ users in an inpatient protocol that includes administration of smoked MJ, followed by monitored abstinence with daily behavioral assessments, and PET imaging with 11C-OMAR. PET data will collected in 10 matched controls for comparison. The proposed study is an important first step to determine whether localized CB1R changes in female MJ users help explain, and provide a neurobiological target for intervention. Results will increase knowledge of cannabinoid mechanisms of cannabis use and severity of dependence in females, an understudied population.
Study Type
INTERVENTIONAL
Allocation
NON_RANDOMIZED
Purpose
BASIC_SCIENCE
Masking
SINGLE
Enrollment
28
11C-OMAR is a PET radiotracer that binds to cannabinoid type 1 receptors (CB1R). It is an analog of the CB1R antagonist/inverse agonist rimonabant. 11C-OMAR was developed, synthesized and validated for inhuman use at the Johns Hopkins University PET center.
Cannabis will be administered to cannabis users. Doses include 0 and 25 mg THC.
Johns Hopkins Bayview Medical Center
Baltimore, Maryland, United States
Distribution Volume (VT)
Distribution Volume (VT) is the quantification of 11C-OMAR binding to the CB1R; Per our statistical plan we examined VT for eight volumes of interest in the brain (ventral striatum, amygdala, putamen, cingulate, globus pallidus, insula, frontal cortex, and hippocampus) as well as the composite VT for the brain. The unit of measure is mL/cm\^3.
Time frame: Collected during 90-min PET study
Peak Change From Baseline Marijuana Withdrawal Discomfort Score
Marijuana withdrawal discomfort will be self-reported using the marijuana withdrawal checklist, available via PhenXToolkit.org. Items are: depressed mood, irritability, nervousness/anxiety, restlessness, increased aggression, increased anger, violent outbursts, nausea, decreased appetite, stomach pain, shakiness, sweating, sleep difficulty, strange/wild dreams, craving to smoke cannabis, diarrhea/loose stools, dizziness, muscle spasms/aches, hiccups, stuffy nose, feverish feeling, hot flashes, chills, increased appetite, headaches, fatigue/tiredness, yawning, difficulty concentrating, general physical discomfort, and other. Each item is rated as 0=none, 1=mild, 2=moderate, or 3=severe. A sum score is calculated from items that are valid, reliable cannabis withdrawal symptoms (Budney et al, 2003, Journal of Abnormal Psychology,112(3): 393-402). A higher score represents more severe withdrawal. Scores range from 0-36.
Time frame: Up to 5 days
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