Presentation Archive Category

Still Testing Positive: Implications of Persistent Blood THC Concentrations in Regular Cannabis Users

April 24, 2025

At the April CMCR Investigators’ Meeting, Ray Suhandynata, Ph.D., DABCC, Assistant Professor at UC San Diego in the Department of Pathology and Skaggs School of Pharmacy and Pharmaceutical Sciences, presented his ongoing research investigating the implications of THC blood levels on driving impairment among regular cannabis users. A total of 191 users were randomized into three groups—0% THC (placebo), 5.9% THC, and 13.4% THC—and assessed through driving simulations, blood/saliva analyses, and standardized field sobriety tests. Baseline THC concentrations varied, with frequent users showing higher residual THC even after 48-hour abstention. Results indicated no relationship between immediate post-smoking blood THaC levels and driving performance. Importantly, many regular users exceeded “per se” DUI cannabis (DUIC) thresholds, including 40% surpassing zero-tolerance limits and nearly 25% exceeding the 2 ng/mL cutoff days after last use. Despite these elevated baseline THC levels, driving simulation scores were unaffected. The data challenge the validity of current DUIC “per se” statutes, suggesting they may lead to unwarranted impairment charges. Incorporating additional toxicological measures, such as oral fluid THC assays, significantly enhanced classification accuracy, reducing false positives. Future research will explore impairment effects using contemporary cannabis products (e.g., concentrates).

Ray Suhandynata, Ph.D., DABCC
Dr. Suhandynata is an Assistant Professor at UC San Diego in the Department of Pathology and Skaggs School of Pharmacy and Pharmaceutical Sciences. He serves as the Associate Director of the CMCR Reference Laboratory and provides clinical oversight for Clinical Chemistry and Clinical Toxicology laboratories at UC San Diego Health. His research includes developing mass spectrometry applications in forensic, pre-clinical, and clinical laboratories, focusing particularly on enhancing the predictive value of forensic toxicology in officer-performed field sobriety testing.

Steering the Integration of Medicinal Cannabis in Healthcare: The Cannabis & Health Research Initiative

March 27, 2025

At the March CMCR Investigators' Meeting, Ryan Vandrey, Ph.D., Professor at the Behavioral Pharmacology Research Unit (BPRU) at Johns Hopkins University, presented his ongoing research in the field of medicinal cannabis. Dr. Vandrey described the Cannabis & Health Research Initiative, a longitudinal observational study tracking adults newly initiating medicinal cannabis use through a patient registry. The study examines trends in cannabis product use, dosage, and associated health outcomes across different medical conditions, with the goal of assessing changes over time. Dr. Vandrey also highlighted the development of the Cannabis Use Questionnaire (CUQ), an instrument designed to capture detailed information on cannabis product types, chemotypes, doses, frequency, and other usage characteristics. Additionally, he presented a related project leveraging machine learning and natural language processing to systematically extract and analyze cannabis-related data from electronic medical records. Dr. Vandrey encouraged those interested in further details to visit cannabisandhealth.org.

Regular Cannabis Use and Cardiovascular Health:  
Insights from NHANES, MESA, and CARDIA

February 27, 2025

At the February CMCR Investigators’ Meeting, Jamie Corroon, ND, MPH, Assistant Project Scientist in the CMCR at the UC, San Diego, summarized findings from his two-year fellowship in cardiovascular disease epidemiology within the Department of Family Medicine. Dr. Corroon presented the results of five studies that investigated associations between regular cannabis use and several cardiovascular outcomes, including blood pressure, hypertension, carotid artery calcification, and heart attack.

Dr. Corroon and colleagues found no association between regular cannabis use and the prevalence or incidence of hypertension. These studies also found no associations with either the duration of regular use or recency of use. Additionally, there was no relationship when stratifying the analyses by sex, race/ethnicity, or tobacco cigarette smoking status. Similarly, the research showed no association between cannabis use and heart attacks or with the prevalence or extent of calcified plaque in the carotid arteries.

Studies presented:

1. Associations Between Monthly Cannabis Use and Myocardial Infarction in Middle-Aged Adults: NHANES 2009 to 2018
2. Trends in Cannabis Use, Blood Pressure, and Hypertension in Middle-Aged Adults: Findings From NHANES, 2009-2018
3. Regular cannabis smoking and carotid artery calcification in the Multi-Ethnic Study of Atherosclerosis (MESA)
4. Blood pressure and hypertension in older adults with a history of regular cannabis use: findings from the Multi-Ethnic Study of Atherosclerosis
5. Lifetime Cannabis Use and Incident Hypertension: The Coronary Artery Risk Development in Young Adults (CARDIA) study (In progress)

Do Differences in Brain Anatomy in Children
Predispose to Later Substance Use?

January 23, 2025

At the January CMCR Investigators’ Meeting, Alex P. Miller, Ph.D., Assistant Professor of Psychiatry at Indiana University School of Medicine, gave a presentation at the CMCR Investigators' Meeting on January 23, 2025. His presentation focused on the results of his recently published longitudinal study investigating associations between neuroanatomical differences in children’s brains and later substance use initiation, including cannabis use. The study, published in JAMA Network Open, used data from the Adolescent Brain Cognitive Development (ABCD) Study, analyzed brain scans from 9,804 children aged 9 to 11, and tracked their substance use initiation over several years.

Among their findings, Dr. Miller and colleagues reported that children who later began using cannabis had smaller right caudate volumes before initiating use. This suggests that preexisting brain differences may predispose individuals to substance use, rather than cannabis use causing these differences. These findings challenge the idea that all brain changes observed in cannabis users are caused by the drug and highlight the need for further longitudinal research.