Clinical Research Directory

Understanding the Clinical Pharmacology of Marijuana-Tobacco Co-administration

This is a crossover, randomized, double-blinded clinical pharmacology study enrolling dual cannabis-tobacco smokers to better understand the combined effects of co-administering cannabis and tobacco. The project aims to describe the pharmacokinetics and pharmacodynamics of marijuana-tobacco co-administration by delivering THC and nicotine in various combinations. This foundational study will establish a research program focused on elucidating the public health consequences of marijuana-tobacco co-use.

Modulation of THC Effects by CBD: a Dose-ranging Study

The purposes of this study are 1) to determine if CBD modulates THC-induced acute psychoactive effects at different CBD:THC ratios, compared with the control product (0:20, 20:20, 40:20, 80:20, 120:20) and 2) to determine if different doses of CBD modulate other THC induced behavioral effects, compared with the control product and 3)To explore qualitatively whether CBD modulates THC effects by mechanisms that are not detected with standard clinical research tools.

Cannabis THC Potency, Metabolism, and Cognitive Impairment in Young Adults

The goal of this interventional study is to determine the impact of high potency THC product use on cognitive function of young adults aged 21-25. The main question it aims to answer is: will cannabis users who switch to less potent THC products demonstrate improved cognitive function compared to baseline? Other questions this study aims to answer include: * Can researchers accurately assess THC consumption among frequent cannabis users? * Can researchers effectively incentivize cannabis users to use less potent THC products? * Do genetic variations in THC metabolism impact urinary THC excretion? * Do genetic variations in THC metabolism impact cognitive performance in cannabis users? * Are quantitative urinary THC values predictive of cognitive impairment? * How can researchers use research findings to inform harm reduction practices for people who use cannabis? Participants will submit blood and urine samples and be incentivized to use less potent THC products.

Pilot fMRI Studies of Aging-Related Effects of THC

The purpose of this study is to begin investigating acute impairment of various forms of memory and learning by Tetrahydrocannabinol (THC) in cannabis (CNB) compared to placebo, in a 2-session per subject double-blind, random assignment, placebo-controlled counterbalanced design in young to middle-aged adults.

THC Titration of High-Potency Cannabis Concentrates

High-potency cannabis use is associated with public health risks, such as cannabis use disorder, psychotic disorders, and impaired cognition. Legal markets in the US and Canada are geared towards the commercialization of high-tetrahydrocannabinol (THC) products, including concentrates as high as 90-95%. The cannabis industry has resisted regulation of higher-potency products claiming that cannabis consumers naturally self-titrate their use, but the limited evidence to date suggests that even though consumers may use less cannabis as potency rises, consuming higher potency products still leads to greater THC consumption. The investigators will use a randomized crossover trial to evaluate the ability of 36 regular cannabis consumers (18 females and 18 males) to self-titrate the THC dose when vaping concentrates to achieve the desired psychoactive effects. The investigators will also characterize and compare the subjective, cognitive, physiological, and pharmacokinetic effects between cannabis concentrates of different potencies (30%, 60%, and 90% THC). Working with US scientists, the setting of this study will be Toronto, Canada, in the context of federal legalization of cannabis, unique access to cannabis products not available in the US for research purposes, and an encouraging regulatory environment. The investigators will test commercial products that are representative of the THC ranges available in the legal market. Aim 1: To evaluate the ability of regular cannabis consumers to self-titrate their THC dose when vaping concentrates of different potencies. The investigators will compare markers of titration (biological: THC blood levels; behavioral: inhalation topography; subjective: self-reported levels of intoxication) over a range of potencies for a comprehensive characterization of titration practice. The investigators hypothesize that participants will be able to partially but not proportionally reduce THC intake with increase in THC potency. In other words, the investigators anticipate that the proportional decrease in blood THC levels will be lower than the proportional increase in THC concentrations. Aim 2: To compare the cognitive impairment, physiological effects, and addiction liability of consuming lower versus higher THC potency concentrates. The investigators hypothesize that cognitive impairment and physiological effects will be less pronounced with lower-THC concentrates in a dose-response fashion. The investigators will also explore differences in addiction liability between potencies as higher THC concentrations may result in greater dysphoric reactions. These acute effects may be related to long term harms such as accidents, CVD events, and CUD. Exploratory Aim: To explore sex differences in titration efficiency, blood THC concentrations, cognitive impairment, physiological effects, and addiction liability. The investigators propose to analyze sex differences in our primary and secondary outcomes (e.g., whether females will be able to titrate more efficiently than males). This experimental evidence will provide data on the potential acute harms related to concentrates and inform policy decisions on the need to decrease access and/or prevent their initiation and implement information and education campaigns to increase awareness on the risks of using them.

Multimodal Magnetoencephalography and Electroencephalography Exploration of the Acute Effects of THC Exposure on Neural Noise and Information Transmission Within Working Memory Networks

The purpose of this study is to use non-invasive brain imaging methods (MEG and EEG) to characterize the effects of THC on brain activity during learning.

Probing the Cannabinoid System in Individuals With a Family History of Psychosis

The overall purpose of this study is to determine whether a family history of psychosis is associated with an altered cannabinoid system. This will be tested by studying individuals with and without a family history of psychosis and comparing their responses to delta 9-tetrahydrocannabinol (THC), a probe of the cannabinoid system. We hypothesize, that compared to controls with no family history of psychoses, individuals with a family history of psychoses will have an altered response to THC.

Behavioral Pharmacology of Orally Administered THC and D-limonene

The current clinical trial will investigate the effects of orally administered d-limonene (limonene), delta-9-tetrahydrocannabinol (THC) and the combination in healthy adult volunteers.

THC Memory & Reward Learning Pilot

Tetrahydrocannabidiol (THC) is the psychoactive chemical in cannabis that makes people high. This study aims to dissect acute impairment of various forms of memory and learning by THC in cannabis compared to placebo. Impairment will be assessed via a short cognitive test battery and then subjects will complete four tasks in the fMRI scanner.

Effects of Cannabidiol and Tetrahydrocannabinol on Microbiome and Neuroinflammation in HIV

This study has the potential to contribute to a more complete understanding of the independent and combined effects of cannabis use and HIV on the brain and on inflammation. Such knowledge may inform future strategies for treating brain disease and inflammation. Participants will be randomly assigned to one of two groups, both of which will receive the same treatment in a different order over a period of about 6 weeks. The visits include physical examinations, blood tests, and other procedures designed to monitor subject safety and measure the effects of the study drug.