Preliminary Evidence for Cannabis and Nicotine Urinary Metabolites as Predictors of Verbal Memory Performance and Learning Among Young Adults

Review and Call for Improved Cannabis Measurement and the Potential for Leveraging Cannabis Seed-To-Sale Systems

International consensus has emerged, which proposes that the measurement and standardization of the quantity of THC potency, or dose (mgTHC), is a requisite for identifying consistent relationships between patterns of cannabis use and the risk for negative health outcomes, especially critical given the increasing number of U.S. states and European countries considering legalizing cannabis for recreational use. Despite the lack of measurement approaches that provide accurate, real-time data on THC dosage, the number of states that have implemented legal adult use cannabis markets has coincided with the use of regulatory seed-to-sale or track-and-trace systems. Seed-to-sale tracking systems are designed to track the amount of cannabis cultivated, and typically leverage biochemical testing contractors to label the THC potencies and amounts on a diverse array of cannabis products. We propose leveraging seed-to-sale tracking systems to facilitate a more objective measure of THC potency. In the current review, we will: 1) summarize the complexities of accurately measuring the multidimensional aspects of cannabis use patterns; 2) review recent advancements in quantifying THC and the importance of standardizing THC dose in measuring cannabis use; and 3) discuss the potential value of future research efforts examining how state-level seed-to-sale tracking data can inform the standard THC dose.

A preliminary investigation of physical and mental health features of cannabis & nicotine co-use among adolescents and young adults by sex

INTRODUCTION

Cannabis and nicotine/tobacco products (NTP) are commonly co-used in adolescence and young adulthood; however, limited research has been done on predictive health behaviors to co-use. The current study is a preliminary investigation into the relationships of modifiable health behaviors on cannabis and NTP co-use in adolescents and young adults.

METHOD

221 participants (ages 16-22) were characterized into cannabis use only (N = 55), NTP use only (N = 20), cannabis and NTP co-use (used cannabis and NTP; N = 96) and control (no use; N = 50) groups based on past 30-day use. Self-report measures for physical activity, sleep quality, mental health, and reward responsivity were utilized. Participants were given a comprehensive neurocognitive battery. Logistic regressions of self-report measures and fluid intelligence composite scores on substance use group status were run stratified by sex.

RESULTS

Higher approach reward sensitivity traits were associated with increased likelihood of cannabis use only (Odds Ratio (OR) = 1.15, p = .036) in female participants. Increased aerobic activity was associated with decreased likelihood of cannabis use only (OR = 0.91, p = .047) and cannabis and NTP co-use (OR = 0.88, p = .007) in female participants. Higher anxiety was associated with increased likelihood of cannabis NTP co-use (OR = 1.51, p = 0.025) in male participants.

DISCUSSION

Several health behaviors were linked with cannabis use and cannabis and NTP co-use in both females and male adolescents and young adults. Health markers differed by sex suggesting differing mechanisms of substance co-use. This study informs targetable health behaviors for prevention and intervention efforts.

Nicotine use during late adolescence and young adulthood is associated with changes in hippocampal volume and memory performance

Background

With the advent of electronic nicotine delivery systems, the use of nicotine and tobacco products (NTPs) among adolescents and young adults remains high in the US. Use of e-cigarettes additionally elevates the risk of problematic use of other substances like cannabis, which is often co-used with NTPs. However, their effects on brain health, particularly the hippocampus, and cognition during this neurodevelopmental period are poorly understood.

Methods

Healthy late adolescents/young adults (N = 223) ages 16-22 completed a structural MRI to examine right and left hippocampal volumes. Memory was assessed with the NIH Toolbox Picture Sequence Memory Test (PSMT) and Rey Auditory Verbal Learning Test (RAVLT). Cumulative 6-month NTP and cannabis episodes were assessed and modeled continuously on hippocampal volumes. Participants were then grouped based on 6-month NTP use to examine relationships with the hippocampus and memory: current users (CU) endorsed weekly or greater use; light/abstinent users (LU) endorsed less than weekly; and never users (NU).

Results

NTP use predicted larger hippocampal volumes bilaterally while cannabis use had no impact nor interacted with NTP use. For memory, larger left hippocampal volumes were positively associated with PSMT performance, RAVLT total learning, short delay and long delay recall for the NU group. In contrast, there was a negative relationship between hippocampal volumes and performances for LU and CU groups. No differences were detected between NTP-using groups.

Conclusion

These results suggest that the hippocampus is sensitive to NTP exposure during late adolescence/young adulthood and may alter typical hippocampal morphometry in addition to brain-behavior relationships underlying learning and memory processes.

Neurite Orientation Dispersion and Density Imaging (NODDI) of Brain Microstructure in Adolescent Cannabis and Nicotine Use

INTRODUCTION

Despite evidence suggesting deleterious effects of cannabis and nicotine tobacco product (NTP) use on white matter integrity, there have been limited studies examining white matter integrity among users of both cannabis and nicotine. Further, updated white matter methodology provides opportunities to investigate use patterns on neurite orientation dispersion and density (NODDI) indices and subtle tissue changes related to the intra- and extra-neurite compartment. We aimed to investigate how cannabis and NTP use among adolescents and young adults interacts to impact the white matter integrity microstructure.

MATERIALS AND METHODS

A total of 221 participants between the ages of 16 and 22 completed the Customary Drinking and Drug Use Record (CDDR) to measure substance use, and underwent a magnetic resonance imaging (MRI) session. Participants were divided into NTP-control and NTP groupings and cannabis-control and cannabis groupings (≥26 NTP/cannabis uses in past 6 months). Tract-Based Spatial Statistics (TBSS) and two-way between-subjects ANOVA investigated the effects of NTP use group, cannabis use group, and their interaction on fractional anisotropy (FA) and NODDI indices while controlling for age and biological sex.

RESULTS

NTP use was associated with decreased FA values and increased orientation dispersion in the left anterior capsule. There were no significant effects of cannabis use or the interaction of NTP and cannabis use on white matter outcomes.

DISCUSSION

NTP use was associated with altered white matter integrity in an adolescent and young adult sample. Findings suggest that NTP-associated alterations may be linked to altered fiber tract geometry and dispersed neurite structures versus myelination, as well as differential effects of NTP and cannabis use on white matter structure. Future work is needed to investigate how altered white matter is related to downstream behavioral effects from NTP use.

Cannabis use and neurocognitive performance at 13-14 Years-Old: Optimizing assessment with hair toxicology in the Adolescent brain cognitive development (ABCD) study

OBJECTIVE

Cannabis is widely used, including in early adolescence, with prevalence rates varying by measurement method (e.g., toxicology vs. self-report). Critical neurocognitive development occurs throughout adolescence. Given conflicting prior brain-behavior results in cannabis research, improved measurement of cannabis use in younger adolescents is needed.

METHODS

Data from the Adolescent Brain Cognitive Development (ABCD) Study Year 4 follow-up (participant age: 13-14 years-old) included hair samples assessed by LC-MS/MS and GC-MS/MS, quantifying THCCOOH (THC metabolite), THC, and cannabidiol concentrations, and the NIH Toolbox Cognitive Battery. Youth whose hair was positive for cannabinoids or reported past-year cannabis use were included in a Cannabis Use (CU) group (n = 123) and matched with non-using Controls on sociodemographics (n = 123). Standard and nested ANCOVAs assessed group status predicting cognitive performance, controlling for family relationships. Follow-up correlations assessed cannabinoid hair concentration, self-reported cannabis use, and neurocognition.

RESULTS

CU scored lower on Picture Memory (p = .03) than Controls. Within the CU group, THCCOOH negatively correlated with Picture Vocabulary (r = -0.20, p = .03) and Flanker Inhibitory Control and Attention (r = -0.19, p = .04), and past-year cannabis use was negatively associated with List Sorting Working Memory (r = -0.33, p = .0002) and Picture Sequence Memory (r = -0.19, p = .04) performances.

CONCLUSIONS

Youth who had used cannabis showed lower scores on an episodic memory task, and more cannabis use was linked to poorer performances on verbal, inhibitory, working memory, and episodic memory tasks. Combining hair toxicology with self-report revealed more brain-behavior relationships than self-report data alone. These youth will be followed to determine long-term substance use and neurocognition trajectories.

The Combined Effects of Nicotine and Cannabis on Cortical Thickness Estimates in Adolescents and Emerging Adults

Early life substance use, including cannabis and nicotine, may result in deleterious effects on the maturation of brain tissue and gray matter cortical development. The current study employed linear regression models to investigate the main and interactive effects of past-year nicotine and cannabis use on gray matter cortical thickness estimates in 11 bilateral independent frontal cortical regions in 223 16-22-year-olds. As the frontal cortex develops throughout late adolescence and young adulthood, this period becomes crucial for studying the impact of substance use on brain structure. The distinct effects of nicotine and cannabis use status on cortical thickness were found bilaterally, as cannabis and nicotine users both had thinner cortices than non-users. Interactions between nicotine and cannabis were also observed, in which cannabis use was associated with thicker cortices for those with a history of nicotine and tobacco product (NTP) use in three left frontal regions. This study sheds light on the intricate relationship between substance use and brain structure, suggesting a potential modulation of cannabis' impact on cortical thickness by nicotine exposure, and emphasizing the need for further longitudinal research to characterize these interactions and their implications for brain health and development.

Adult use of highly-potent Δ9-THC cannabis concentrate products by U.S. state cannabis legalization status, 2021

BACKGROUND

Compared to plant/flower cannabis products, cannabis concentrates have higher average potency of delta-9-tetrahydrocannabinol (Δ9-THC), which may be associated with greater likelihood of cannabis-related harms. Information on factors associated with use of cannabis concentrates is needed.

METHODS

Respondents were 4,328 adult past-7-day cannabis users from all 50 U.S. states and Washington DC (DC) who participated in an online 2021 survey. Using logistic regression to generate adjusted odds ratios (aOR), we investigated whether participants in states that enacted recreational cannabis laws (RCL, 12 states plus DC [treated as a state], n = 1,236) or medical cannabis laws (MCL-only, 23 states, n = 2,030) by December 31, 2020 were more likely than those in states without cannabis laws (no-CL, 15 states, n = 1,062) to use cannabis concentrate products in the prior 7 days.

RESULTS

Most participants (92.4%) used plant material in the prior 7 days; 57.0% used cannabis concentrates. In RCL, MCL and no-CL states, concentrate use was reported by 61.5%, 56.6%, and 52.5%, respectively. Compared to participants in no-CL states, odds of using cannabis concentrate products were greater among those in RCL states (aOR = 1.47; CI = 1.17-1.84) and MCL-only states (aOR = 1.29; CI = 1.08-1.55). Whether states had legally-authorized dispensaries had little effect on results.

CONCLUSION

Results suggest that individuals in MCL-only and RCL states are more likely to use cannabis concentrate products. Determining mechanisms underlying these results, e.g., commercialization, could provide important information for prevention. Clinicians should be alert to patient use of concentrates, especially in MCL-only and RCL states. Continued monitoring is warranted as additional states legalize cannabis use.

Young Adult E-Cigarette and Combustible Tobacco Users Attitudes, Substance Use Behaviors, Mental Health, and Neurocognitive Performance

Nicotine and tobacco product (NTP) use has escalated, largely due to the advent of e-cigarettes. The NTP administration method (i.e., combustible cigarette, e-cigarette) may be an important differentiator. We assessed young adult substance use history, nicotine attitudes, mental health, and neurocognition by the NTP use method. Emerging adults (16–22 year olds) were divided into combustible NTP users (Combustible+ = 79, had used any combustible NTP in the last 6 months), non-combustible users (E-Cig = 43, had used non-combustible NTP, in the past 6 months), and NTP Naïve (n = 79; had not used NTP in the past 6 months) based on past 6-month NTP use patterns. Participants completed self-report and objective neurocognition measures. Analysis of covariance assessed mental health and neurocognition by group, controlling for confounds and correcting for multiple comparisons. Nicotine groups reported more favorable attitudes toward combustible cigarette and e-cigarette use, with taste as the primary reason for e-cigarette use. Combustible+ reported more nicotine dependence and craving. Substance use differed by group, with Combustible+ using the most NTP, alcohol, and cannabis. Nicotine groups reported higher depression and stress symptoms; male Combustible+ reported higher depression symptoms than other same-gender groups. Groups did not differ on neurocognition, though cannabis use was associated with inaccurate emotional Stroop responses. Overall, research suggests that young adult combustible users are likely qualitatively different from non-combustible users. Understanding the unique characteristics related to NTP product use will help guide intervention and prevention development.