Investigating the Relationship Between Cannabis Expectancies and Anxiety, Depression, and Pain Responses After Acute Flower and Edible Cannabis Use

Objective: Cannabis has been touted for a host of pharmacological and therapeutic effects and users commonly report reduced symptoms of physical and mental health conditions, including anxiety, depression, and chronic pain. While there is existing empirical evidence supporting these effects of cannabis use, little is known about the extent to which these effects result from pharmacological versus expectancy factors. We evaluated the associations between participants' cannabis expectancies and their acute self-reported reactions after using legal market forms of cannabis with varying levels of cannabidiol (CBD) and Δ9-tetrahydrocannabinol (THC) in three domains: anxiety, depression, and pain. Methods: Fifty-five flower and 101 edible cannabis users were randomly assigned and asked to purchase at a local dispensary one of three products containing varying levels of CBD and THC. Participants completed a baseline assessment where they reported expectancies about general health effects of cannabis use and an experimental mobile laboratory assessment where they administered their assigned products. Edible users also reported their domain-specific expectancies about cannabis use in improving anxiety, depression, and pain. Following administration, participants completed acute indicators of anxiety, depression, and pain operationalized through subjective acute tension, elation, and a single-item measure of pain. Results: Among flower users, more positive expectancies for cannabis to improve general health were correlated with greater reductions in tension at acute post-use. This finding was replicated among edible users. Unlike flower users, more positive expectancies for cannabis to improve general health were also correlated with greater increases in elation and greater reductions in pain among edible users. More positive expectancies for cannabis to improve depression and pain were also correlated with greater increases in elation and greater reductions in pain, respectively, among edible users. Conclusions: Cannabis users' expectancies significantly impacted some of the acute subjective effects of legal market cannabis products. Among both flower and edible users, consistent, significant expectancy effects were found. Results were consistent with prior findings and demonstrate the need to measure and control pre-existing expectancies in future research that involves cannabis administration. Clinical trial registration number: NCT03522103.

Acute Effects of Ad Libitum Use of Commercially Available Cannabis Products on the Subjective Experience of Aerobic Exercise: A Crossover Study

OBJECTIVE

The present study aimed to examine the acute effects of legal-market cannabis on regular cannabis users' subjective responses to exercise in a controlled laboratory environment.

BACKGROUND

Given the stereotype that cannabis is associated with extreme sedentary behavior, there are concerns that cannabis legalization may exacerbate the US physical inactivity epidemic. However, despite these concerns, recent years have seen considerable public interest in the use of cannabis concurrently with exercise (e.g., running).

METHODS

The present study compared participants' experiences of exercise without cannabis to their experiences of exercise after acute ad libitum use of one of two commercially available cannabis flower products: a Δ9-tetrahydrocannabinol-dominant or a cannabidiol-dominant product. Participants (N = 42) were regular cannabis users between the ages of 21 and 39 years (mean = 30.81 years, standard deviation = 4.72 years).

RESULTS

Although participants reported a more positive affect (p < 0.001), enjoyment (p < 0.001), and runner's high symptoms (p < 0.001) during their cannabis (vs non-cannabis) exercise appointment, they also reported more exertion (p = 0.04). Pain levels were very low and did not differ between appointments (p = 0.45). Effects appeared to depend, in part, on cannabinoid content; there was a larger difference in enjoyment (p = 0.02), and a smaller difference in exertion (p = 0.02), between the cannabis and non-cannabis exercise appointments among participants in the cannabidiol (vs Δ9-tetrahydrocannabinol) condition.

CONCLUSIONS

To our knowledge, this is the first study to investigate the acute effects of commercially available cannabis on subjective responses to exercise in a laboratory environment. Our findings suggest that, among regular cannabis users who use cannabis in combination with exercise, cannabis use prior to exercise may lead to increases in both positive and negative aspects of the subjective exercise experience. Research using diverse samples, exercise modalities, and methodologies (e.g., placebo-controlled trials) is needed to establish the generalizability of these findings.

Cannabinoid Exposure and Subjective Effects of THC and CBD in Edible Cannabis Products

Background: The popularity of edible cannabis products continues to grow in states with legal cannabis access, but few studies have investigated the acute effects of these commercially available products. The present study sought to explore the effects of three commercially available edible products with different levels of delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD). Methods: A sample of regular cannabis users (N=99) were evaluated. Fifty participants completed the study procedures in-person, whereas 49 participants completed the study procedures remotely via Zoom. Subjective effects and plasma cannabinoid levels (in-person participants only) were assessed before and 2 h after participants self-administered one of three products ad libitum: a THC-dominant edible product, a CBD-dominant edible product, or a THC+CBD edible product. Results: At the 2-h post-use assessment, among in-person participants, plasma THC and CBD levels were robustly correlated with self-reported milligrams of THC and CBD consumed, respectively. Across all three conditions, in-person and remote participants experienced (1) an increase in subjective intoxication and elation, (2) a decrease in tension, and (3) no change in paranoia from pre-use to post-use. At post-use, participants who used a CBD product reported less intoxication relative to participants who used a THC+CBD or THC-only product. Participants who used a THC+CBD product reported consuming less THC-and displayed lower plasma THC levels (in-person participants)-relative to participants who used a THC-only product, despite reporting similar levels of positive (intoxication, elation, liking) and psychotomimetic (paranoia, tension) effects. Psychotomimetic effects were very low among both in-person and remote participants across all three conditions, and there were no post-use differences across conditions. Conclusions: Findings suggest that experienced users who consumed a THC+CBD product reported similar levels of positive and psychotomimetic effects relative to those who consumed a THC-only product, despite consuming less THC and displaying lower plasma THC concentrations. Given the potential harms associated with acute cannabis reward and long-term THC exposure, further research is needed to establish whether edible cannabis products with CBD pose less risk to users. Future studies should examine whether these effects generalize to samples of infrequent users, who may have less experience with edible cannabis use. ClinicalTrials.gov ID: NCT03522103.

Mindfulness mechanisms in alcohol use: Comparing top-down and bottom-up processes

OBJECTIVE

This study compared two mechanisms by which mindfulness may reduce hazardous drinking: effortful control and craving, "top-down" and "bottom-up" processes, respectively. These relationships were compared in a secondary analysis of a randomized controlled trial of mindfulness-based relapse prevention (MBRP) versus relapse prevention (RP) treatments to explore if they differed based on more explicit versus subtle mindfulness training.

METHOD

A total of 182 individuals (48.4% female; 21-60 years old) who reported drinking > 14/21 drinks/week (for females/males, respectively) in the past 3 months but who wished to quit/reduce their drinking were recruited from Denver and Boulder, CO, United States. Participants were randomly assigned to either 8 weeks of MBRP or RP treatment and completed assessments at baseline, halfway through treatment, and at the end of treatment. The Five-Factor Mindfulness Questionnaire-Short Form, Alcohol Urge Questionnaire, and Effortful Control Scale completed halfway through treatment assessed the predictor, dispositional mindfulness, and mediators, craving and effortful control, respectively. The Alcohol Use Disorder Identification Task was completed after treatment and measured hazardous drinking. Cross-group path analyses were conducted including both mediators/treatments in the same model.

RESULTS

Comparing models with and without equality constraints across treatments, no paths significantly differed based on a chi-square test of difference, χ²(5) = 5.11, p = .40, and only the indirect effect of craving was significant (B = -1.01, p = .01).

CONCLUSIONS

Findings suggest mindfulness may be associated with hazardous drinking reductions through craving but not effortful control and this indirect relationship works similarly across treatments engendering mindfulness explicitly and implicitly. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Acute and Extended Anxiolytic Effects of Cannabidiol in Cannabis Flower: A Quasi-Experimental ad libitum Use Study

Objective: Δ9-tetrahydrocannabinol (THC) and cannabidiol (CBD) have varying pharmacological actions with differential effects on acute and extended affective states, incuding anxiety. We aimed to study these effects on anxiety in legal market forms of cannabis. Method: This study makes use of a nonequivalent control group quasiexperimental design. Forty-two participants with anxiety symptions who were not using cannabis were compared to 258 participants with anxiety symptoms who used cannabis flower (∼3-4 times per week). Participants who used cannabis were randomly assigned to one of three legal market cannabis conditions; THC-dominant (24% THC, <1% CBD), THC+CBD (12% THC, 12% CBD), or CBD-dominant (<1% THC, 24% CBD). Changes in anxiety symptoms over 4-weeks were measured by the Patient Global Impression of Change (PGIC) scale and the Depression, Anxiety, and Stress Scale (DASS). Acute changes in subjective mood immediately after cannabis use were measured by the Profile of Mood States (POMS) Elation, Tension, and Paranoia subscales and the Addiction Research Center Inventory intoxication scale. Results: While all participants reported anxiety reductions over the 4-week study on the PGIC (F=30.65, p<0.001) and DASS anxiety measures (F=115.88, p<0.001), ad libitum CBD-dominant cannabis use was associated with lower scores on the DASS anxiety subscale compared to THC-dominant use when accounting for frequency of use (difference=-1.03, SE=0.45, p=0.02). Similarly, acute CBD-dominant cannabis use was associated with lower scores on the POMS tension and paranoia subscales (POMS tension: CBD-dominant vs. THC-dominant: difference=-0.41 SE=0.1, p<0.001; CBD-dominant vs. THC+CBD: difference=-0.28, SE=0.07, p=0.04; POMS paranoia: CBD-dominant vs. THC-dominant: difference=-0.49, SE=0.1, p<0.001; CBD-dominant vs. THC+CBD: difference=-0.33, SE=0.09, p=0.01). Participants in all cannabis conditions experienced acute changes in positive mood and subjective drug effects. Conclusions: This study provides novel information on the impacts of legal market cannabis with varying ratios of THC to CBD in indviduals with anxiety symptoms. Findings suggest that THC did not increase anxiety and that CBD-dominant forms of cannabis were associated with acute tension reduction that may translate to longer-term reductions in anxiety symptoms. Clinical Trial Registration: NCT03491384.

Association between the oral microbiome and brain resting state connectivity in schizophrenia

Recent microbiome-brain axis findings have shown evidence of the modulation of microbiome community as an environmental mediator in brain function and psychiatric illness. This work is focused on the role of the microbiome in understanding a rarely investigated environmental involvement in schizophrenia (SZ), especially in relation to brain circuit dysfunction. We leveraged high throughput microbial 16s rRNA sequencing and functional neuroimaging techniques to enable the delineation of microbiome-brain network links in SZ. N=213 SZ and healthy control (HC) subjects were assessed for the oral microbiome. Among them, 139 subjects were scanned by resting-state functional magnetic resonance imaging (rsfMRI) to derive brain functional connectivity. We found a significant microbiome compositional shift in SZ beta diversity (weighted UniFrac distance, p= 6×10 -3 ; Bray-Curtis distance p = 0.021). Fourteen microbial species involving pro-inflammatory and neurotransmitter signaling and H 2 S production, showed significant abundance alterations in SZ. Multivariate analysis revealed one pair of microbial and functional connectivity components showing a significant correlation of 0.46. Thirty five percent of microbial species and 87.8% of brain functional network connectivity from each component also showed significant differences between SZ and HC with strong performance in classifying SZ from HC, with an area under curve (AUC) = 0.84 and 0.87, respectively. The results suggest a potential link between oral microbiome dysbiosis and brain functional connectivity alteration in relation to SZ, possibly through immunological and neurotransmitter signaling pathways and the hypothalamic-pituitary-adrenal axis, supporting for future work in characterizing the role of oral microbiome in mediating effects on SZ brain functional activity.

Comparing the Efficacy of Mindfulness-Based Relapse Prevention Versus Relapse Prevention for Alcohol Use Disorder: A Randomized Control Trial

OBJECTIVE

This study compared the efficacy of mindfulness-based relapse prevention (MBRP) with relapse prevention (RP) on reducing alcohol consumption. Secondary, exploratory aims assessed moderation of treatment effects by sex and cannabis use.

METHOD

A total of 182 individuals (48.4% female; 21-60 years old) who reported drinking more than 14/21 drinks/week (for women and men, respectively) in the past 3 months but who wished to quit/reduce their drinking were recruited from Denver and Boulder, Colorado. Individuals were randomly assigned to 8 weeks of individual-based MBRP or RP treatment. Participants completed substance use assessments at baseline, halfway through and at the end of treatment, and 20 and 32 weeks after treatment. Primary outcomes were Alcohol Use Disorders Identification Test-consumption questions (AUDIT-C) scores, heavy drinking days (HDD), and drinks per drinking day (DDD).

RESULTS

Across treatments, drinking decreased over time (ps < .001), with a significant time-by-treatment interaction found for HDD (F = 3.50, p < .01). HDD initially decreased in both treatments but remained stable or increased after treatment for MBRP and RP participants, respectively. At follow-up, MBRP participants had significantly less HDD than RP participants. Sex did not moderate treatment effects (ps > .17), whereas cannabis use moderated treatment effects on DDD and HDD (F = 4.89, p < .001, and F = 4.30, p < .005, respectively). High cannabis use frequency was associated with continued posttreatment decreases in HDD/DDD for MBRP participants but increased HDD for RP participants. At low cannabis use frequency levels, HDD/DDD remained stable after treatment across groups.

CONCLUSIONS

Drinking decreases were comparable across treatments, but HDD improvements diminished for RP participants after treatment. In addition, cannabis use moderated treatment efficacy for HDD/DDD.

Associations Between Age and Resting State Connectivity Are Partially Dependent Upon Cardiovascular Fitness

Previous research suggests a marked impact of aging on structural and functional connectivity within the frontoparietal control network (FPCN) and default mode network (DMN). As aging is also associated with reductions in cardiovascular fitness, age-related network connectivity differences reported by past studies could be partially due to age-related declines in fitness. Here, we use data collected as part of a 16-week exercise intervention to explore relationships between fitness and functional connectivity. Young and older adults completed baseline assessments including cardiovascular fitness, health and functioning measures, and an fMRI session. Scan data were acquired on a Siemens 3T MRI scanner with a 32-channel head coil. Results from regression analyses indicated that average connectivity did not differ between young and older adults. However, individual ROI-to-ROI connectivity analyses indicated weaker functional correlations for older adults between specific regions in the FPCN and DMN and, critically, many of these differences were attenuated when fitness was accounted for. Taken together, findings suggest that fitness exerts regional rather than global effects on network connectivity.

Cannabis Use and Resting State Functional Connectivity in the Aging Brain

Several lines of evidence suggest that older adults (aged 65+) sharply increased their cannabis use over the last decade, highlighting a need to understand the effects of cannabis in this age group. Pre-clinical models suggest that cannabinoids affect the brain and cognition in an age-dependent fashion, having generally beneficial effects on older animals and deleterious effects on younger ones. However, there is little research on how cannabis affects the brains of older adults or how older adults differ from younger adults who use cannabis. Resting state functional connectivity (rsFC) measures provide sensitive metrics of age-related cognitive decline. Here we compared rsFC in older adults who are either regular users of cannabis or non-users. We found stronger connectivity between sources in the hippocampus and parahippocampal cortex, and targets in the anterior lobes of the cerebellum in older adult cannabis users relative to non-users. A similar pattern of strengthened connectivity between hippocampal and cerebellar structures was also present in 25-35 year old non-users in comparison to 60-88 year old non-users. These findings suggest that future studies should examine both the potential risks of cannabinoids, as well as a potential benefits, on cognition and brain health for older adults.

Effects of cannabidiol in cannabis flower: Implications for harm reduction

Using a federally compatible, naturalistic at-home administration procedure, the present study examined the acute effects of three cannabis flower chemovars with different tetrahydrocannabinol (THC) to cannabidiol (CBD) ratios, in order to test whether chemovars with a higher CBD content produce different effects. Participants were randomly assigned to ad libitum administration of one of three chemovars (THC-dominant: 24% THC, 1% CBD; THC+CBD: 9% THC, 10% CBD; CBD-dominant: 1% THC, 23% CBD); 159 regular cannabis users (male = 94, female = 65) were assessed in a mobile pharmacology lab before, immediately after, and 1 h after ad libitum administration of their assigned chemovar. Plasma cannabinoids as well as positive (e.g., high, elation) and negative (e.g., paranoia and anxiety) subjective effects were assessed at each time points. Participants who used the CBD-dominant and THC + CBD chemovars had significantly less THC and more CBD in plasma samples compared to participants who used the THC-dominant chemovar. Further, the THC + CBD chemovar was associated with similar levels of positive subjective effects, but significantly less paranoia and anxiety, as compared to the THC-dominant chemovar. This is one of the first studies to examine the differential effects of various THC to CBD ratios using chemovars that are widely available in state-regulated markets. Individuals using a THC + CBD chemovar had significantly lower plasma THC concentrations and reported less paranoia and anxiety while also reporting similar positive mood effects as compared to individuals using THC only, which is intriguing from a harm reduction perspective. Further research is needed to clarify the harm reduction potential of CBD in cannabis products.

Acute objective and subjective intoxication effects of legal-market high potency THC-dominant versus CBD-dominant cannabis concentrates

As the market for cannabis concentrate products grows, the lack of research regarding the effects of concentrated THC and CBD becomes more glaring. The present study analyzes cannabinoid blood levels and subjective outcomes of physical sensation and affective state after ad libitum use of legal-market concentrate products. Recreational cannabis users were randomly assigned to THC- or CBD-dominant concentrate products, completing a baseline session, and an experimental mobile laboratory session consisting of timepoints before, immediately after, and one-hour after concentrate use. THC-dominant concentrates induced higher intoxication, and higher ratings of drug effect and drug liking than the CBD-dominant concentrate. Both products induced immediate feelings of elation, diminishing over the subsequent hour. Subjective outcomes in the CBD-dominant group revealed immediate decreases in tension and anxiety relative to pre-use, while the THC-dominant group only saw significant decreases in anxiety after one hour. Paranoia spiked immediately post-use in THC-dominant concentrate users, returning to baseline within an hour. Overall, the CBD-dominant concentrate invoked positive mood effects, lower intoxication and an absence of undesirable effects experienced with the THC-dominant concentrate, potentially mitigating negative effects when combined. Results support the need for further investigation into harm-reduction potential of concentrated CBD when used alone and with THC.

Associations between self-reported cannabis use frequency, potency, and cannabis/health metrics

BACKGROUND

Research shows that cannabis use frequency is associated with cannabis dependence and health metrics. However, much less is known about how self-reported cannabis potency (THC and CBD) may be associated with the same metrics, and whether any associations exist after accounting for frequency of cannabis use. Moreover, even less is known about how these relations may differ across cannabis product forms. This exploratory study examined 1) associations between cannabis frequency, potency, and cannabis/health metrics, and 2) whether associations between potency and cannabis/health metrics remained after controlling for frequency of use.

METHODS

Using a sample of adult recreational cannabis users in Colorado (N = 300), we tested the relationship between self-reported cannabis use metrics of frequency and potency of flower, edible, and concentrate products with separate measures of problematic cannabis use (i.e., dependence, withdrawal, craving), depression, anxiety, and general perceived health.

RESULTS

Greater frequency of flower and concentrate (but not edible) use were associated with greater problematic cannabis use, and greater concentrate use frequency was also associated with more mental health problems. Partial correlations controlling for average frequency of use across all product forms and CBD potency per product showed that one significant association between THC potency and cannabis/health metrics remained (i.e., higher THC concentrate potency with better health), and one emerged (i.e., higher THC concentrate potency with lower cannabis withdrawal).

CONCLUSIONS

Frequency of use is reliably associated with problematic cannabis use for flower and concentrates, but it did not account for all observed associations in this study. Differences in patterns of associations between frequency and potency and cannabis/health metrics across cannabis forms suggest a need for better understanding user reports of THC and CBD potency, individual differences among users, and improved measurement.

Exploring relationships between alcohol consumption, inflammation, and brain structure in a heavy drinking sample

BACKGROUND

Chronic alcohol consumption is associated with structural brain changes and increased inflammatory signaling throughout the brain and body. Increased inflammation in the brain has been associated with structural damage. Recent studies have also shown that neurofilament light polypeptide (NfL) is released into the systemic circulation following neuronal damage. Although NfL has thus been proposed as a biomarker for neurodegenerative diseases, its connection to alcohol use disorder has not been explored. For this secondary data analysis, we proposed a conceptual model linking alcohol consumption, the pro-inflammatory cytokine IL-6, brain structure, and NfL in heavy drinking participants.

METHODS

Of the 182 individuals enrolled in this study, 81 participants had usable data on gray matter (GM) thickness and 80 had usable data on white matter (WM) diffusivity. A subset of participants had NfL (n = 78) and IL-6 (n = 117) data. An estimate of GM thickness was extracted from middle frontal brain regions using FreeSurfer. Estimated mean WM diffusivity values were extracted from Tract Based Spatial Statistics. NfL and IL-6 were measured in blood. Regression models were used to test individual linkages in the conceptual model. Based on significant regression results, we created a simplified conceptual model, which we tested using path analysis.

RESULTS

In regressions, negative relationships emerged between GM and both drinks per drinking day (DPDD) (p = 0.018) and NfL (p = 0.004). A positive relationship emerged between WM diffusivity and DPDD (p = 0.033). IL-6 was not significantly associated with alcohol use, GM or WM. The final path model demonstrated adequate fit to the data and showed significant, negative associations between DPDD and middle frontal gyrus (MFG) thickness, and between MFG thickness and NfL, but the association between DPDD and NfL was not significant.

CONCLUSIONS

This is the first study to show that heavy drinking is associated with lower GM thickness and higher WM diffusivity and that lower GM thickness is associated with higher circulating NfL. The analyses also show that the effects of drinking do not involve the pro-inflammatory cytokine IL-6.

Investigating Associations Between Inflammatory Biomarkers, Gray Matter, Neurofilament Light and Cognitive Performance in Healthy Older Adults

Background: Exploring biological variables that may serve as indicators of the development and progression of cognitive decline is currently a high-priority research area. Recent studies have demonstrated that during normal aging, individuals experience increased inflammation throughout the brain and body, which may be linked to cognitive impairment and reduced gray matter volume in the brain. Neurofilament light polypeptide (NfL), which is released into the circulation following neuronal damage, has been proposed as a biomarker for neurodegenerative diseases, and may also have utility in the context of normal aging. The present study tested associations between age, peripheral levels of the pro-inflammatory cytokine IL-6, peripheral NfL, brain volume, and cognitive performance in a sample of healthy adults over 60 years old.

Methods: Of the 273 individuals who participated in this study, 173 had useable neuroimaging data, a subset of whom had useable blood data (used for quantifying IL-6 and NfL) and completed a cognitive task. Gray matter (GM) thickness values were extracted from brain areas of interest using Freesurfer. Regression models were used to test relationships between IL-6, NfL, GM, and cognitive performance. To test putative functional relationships between these variables, exploratory path analytic models were estimated, in which the relationship between age, IL-6, and working memory performance were linked via four different operationalizations of brain health: (1) a latent GM variable composed of several regions linked to cognitive impairment, (2) NfL alone, (3) NfL combined with the GM latent variable, and (4) the hippocampus alone.

Results: Regression models showed that IL-6 and NfL were significantly negatively associated with GM volume and that GM was positively associated with cognitive performance. The path analytic models indicated that age and cognitive performance are linked by GM in the hippocampus as well as several other regions previously associated with cognitive impairment, but not by NfL alone. Peripheral IL-6 was not associated with age in any of the path models.

Conclusions: Results suggest that among healthy older adults, there are several GM regions that link age and cognitive performance. Notably, NfL alone is not a sufficient marker of brain changes associated with aging, inflammation, and cognitive performance.

Effects of cannabis use on alcohol consumption in a sample of treatment-engaged heavy drinkers in Colorado

BACKGROUND AND AIMS

Cannabis is commonly used among people who drink alcohol, but evidence suggests a nuanced relationship between alcohol consumption and cannabis use. In particular, among individuals undergoing alcohol treatment the impact of cannabis on alcohol intake may depend upon cannabis use frequency. We aimed to test the effects of within-day cannabis use on total drinks consumed and likelihood of binge drinking on a given day among all participants and compare these relationships between males and females and between individuals who reported infrequent and frequent cannabis use.

DESIGN

This observational study is a substudy of a larger randomized controlled trial (RCT). Individuals were included from the RCT if they reported any cannabis use and were divided into groups based on cannabis use patterns. Alcohol use was compared within and between groups.

SETTING

Individuals were recruited from 2016 to 2020 from community and university settings in Denver and Boulder, CO, USA.

PARTICIPANTS

Of the 182 individuals enrolled in the RCT, 96 cannabis-using subjects were included in these analyses.

MEASUREMENTS

Subjects completed a time-line follow-back (TLFB) at baseline, 4, 8 (end of treatment) and 20 weeks. Daily data on alcohol and cannabis use from the TLFB at all time-points were analyzed.

FINDINGS

Across the sample (n = 96), individuals drank approximately 29% fewer drinks [95% confidence interval (CI) = 18-39%, P < 0.001] and were 2.06 times (95% CI =1.37-3.08, P < 0.001) less likely to have a binge-drinking episode on days that cannabis was used compared with days that cannabis was not used. These patterns were observed in males, females and the infrequent and frequent cannabis use groups. Findings were inconclusive regarding differences in the association between cannabis use and alcohol outcomes when comparing males and females and when comparing infrequent and frequent cannabis use groups.

CONCLUSIONS

Heavy drinkers engaged in treatment to reduce their alcohol consumption who also use cannabis appear to increase their cannabis use on days when they reduce their alcohol consumption.

The Effects of Exercise Duration and Intensity on Breast Cancer-Related DNA Methylation: A Randomized Controlled Trial

Emerging research suggests that one mechanism through which physical activity may decrease cancer risk is through its influence on the methylation of genes associated with cancer. The purpose of the current study was to prospectively test, using a rigorous experimental design, whether aerobic exercise affects DNA methylation in genes associated with breast cancer, as well as whether quantity of exercise completed affects change in DNA methylation in a dose-response manner. 276 women (M age = 37.25, SD = 4.64) were recruited from the Denver metro area for a randomized controlled trial in which participants were assigned to a supervised aerobic exercise program varying in a fully crossed design by intensity (55-65% versus 75-85% of VO2max) and duration (40 versus 20 min per session). DNA methylation was assessed via blood samples provided at baseline, after completing a 16-week supervised exercise intervention, and six months after the intervention. 137 participants completed the intervention, and 81 had viable pre-post methylation data. Contrary to our hypotheses, total exercise volume completed in kcal/kg/week was not associated with methylation from baseline to post-intervention for any of the genes of interest. An increase in VO2max over the course of the intervention, however, was associated with decreased post-intervention methylation of BRCA1, p = 0.01. Higher levels of self-reported exercise during the follow-up period were associated with lower levels of GALNT9 methylation at the six-month follow-up. This study provides hypothesis-generating evidence that increased exercise behavior and or increased fitness might affect methylation of some genes associated with breast cancer to reduce risk.

Investigating sex differences in acute intoxication and verbal memory errors after ad libitum cannabis concentrate use

BACKGROUND

An innovative naturalistic at-home administration procedure was used to investigate sex differences in subjective drug effects and verbal memory errors after ad libitum use of high potency state legal market Δ9-tetrahydrocannabinol (THC) concentrate.

METHODS

Regular concentrate users were randomly assigned to ad libitum administration of one of two cannabis concentrate products (70 % or 90 % THC) that they purchased from a dispensary. 65 participants (N = 34 men, N = 31 women) were assessed in a mobile pharmacology lab before, immediately after, and 1 -h after ad libitum concentrate use. Plasma cannabinoids (THC, 11-OH-THC, CBD), subjective drug effects, and verbal memory errors were assessed at all three time points.

RESULTS

Although men and women exhibited similar plasma 11-OH-THC levels across time (p = .10), sex differences were found in plasma THC and CBD after legal market concentrate use, with men displaying significantly higher levels of plasma THC and CBD immediately after cannabis concentrate use (plasma THC [ng/mL]: M_men = 489.88, M_women = 135.08, p < .001; plasma CBD [ng/mL]: M_men = 1.14, M_women = 0.53, p = .04). Despite this, sex differences in subjective effects and verbal memory errors did not emerge, although women reported a steeper decrease in drug liking after use (p = .04).

CONCLUSION

These data provide the first look at sex differences after acute naturalistic cannabis concentrate use, and suggest much higher THC exposure in men versus women, but similar acute drug and impairment effects across the sexes. Further studies are needed to determine the mechanisms (e.g. tolerance, cannabinoid metabolism, smoking topography) behind these findings.

THC and CBD effects on alcohol use among alcohol and cannabis co-users

OBJECTIVE

Conflicting evidence exists regarding the effects of cannabis on alcohol consumption, with some studies suggesting that cannabis is a substitute for alcohol, whereas others suggest that cannabis complements alcohol, thereby increasing drinking. Cannabidiol (CBD) has shown preclinical promise in decreasing alcohol consumption. This study explores the effects of cannabis containing different potencies of CBD and delta-9-tetrahydrocannabinol (THC) on alcohol consumption.

METHOD

In this naturalistic observational study, 120 cannabis and alcohol-using adults (mean age = 33.2 years, 39.2% female, 83.3% white) were assigned to use one of three legal-market cannabis strains (predominantly THC, predominantly CBD, and CBD + THC) ad libitum for 5 days. Timeline Followback data on drinking and cannabis use were collected at a baseline session pertaining to the 30 days prior to the ad libitum period, and data regarding alcohol and cannabis use during the 5-day period were collected at follow-up (FU), immediately following the 5-day period.

RESULTS

Regression models tested strain differences in drinking outcomes during the ad libitum period. Orthogonal contrast codes were created comparing the CBD group with the other two groups and comparing the THC group with the CBD + THC group. The CBD group drank fewer drinks per drinking day (p < .05), had fewer alcohol use days (p < .05), and fewer alcohol and cannabis co-use days (p < .05) compared with the other groups. No differences emerged between the THC and the CBD + THC group.

CONCLUSIONS

Cannabinoid content should be considered in studies of alcohol and cannabis co-use. Findings are consistent with preclinical work, suggesting that CBD may be associated with decreased alcohol consumption. (PsycInfo Database Record (c) 2021 APA, all rights reserved).

Association of Naturalistic Administration of Cannabis Flower and Concentrates With Intoxication and Impairment

IMPORTANCE

The rapidly growing legal cannabis market includes new and highly potent products, the effects of which, to our knowledge, have not previously been examined in biobehavioral research studies because of federal restrictions on cannabis research.

OBJECTIVE

To use federally compatible, observational methods to study high-∆9-tetrahydrocannabinol (THC) legal market forms of cannabis.

DESIGN, SETTING, AND PARTICIPANTS

In this cohort study with a between-groups design that was conducted in a community and university setting, cannabis flower users and concentrate users were randomly assigned to higher- vs lower-THC products within user groups. Participants completed a baseline and an experimental mobile laboratory assessment that included 3 points: before, immediately after, and 1 hour after ad libitum legal market flower and concentrate use. Of the 133 individuals enrolled and assessed, 55 regular flower cannabis users (41.4%) and 66 regular concentrate cannabis users (49.6%) complied with the study's cannabis use instructions and had complete data across primary outcomes.

EXPOSURES

Flower users were randomly assigned to use either 16% or 24% THC flower and concentrate users were randomly assigned to use either 70% or 90% THC concentrate that they purchased from a dispensary.

MAIN OUTCOMES AND MEASURES

Primary outcome measures included plasma cannabinoids, subjective drug intoxication, and neurobehavioral tasks testing attention, memory, inhibitory control, and balance.

RESULTS

A total of 121 participants completed the study for analysis: 55 flower users (mean [SD] age, 28.8 [8.1] years; 25 women [46%]) and 66 concentrate users (mean [SD] age, 28.3 [10.4] years; 30 women [45%]). Concentrate users compared with flower users exhibited higher plasma THC levels and 11-hydroxyΔ9-THC (THC's active metabolite) across all points. After ad libitum cannabis administration, mean plasma THC levels were 0.32 (SE = 0.43) μg/mL in concentrate users (to convert to millimoles per liter, multiply by 3.18) and 0.14 (SE = 0.16) μg/mL in flower users. Most neurobehavioral measures were not altered by short-term cannabis consumption. However, delayed verbal memory (F1,203 = 32.31; P < .001) and balance function (F1,203 = 18.88; P < .001) were impaired after use. Differing outcomes for the type of product (flower vs concentrate) or potency within products were not observed.

CONCLUSIONS AND RELEVANCE

This study provides information about the association of pharmacological and neurobehavioral outcomes with legal market cannabis. Short-term use of concentrates was associated with higher levels of THC exposure. Across forms of cannabis and potencies, users' domains of verbal memory and proprioception-focused postural stability were primarily associated with THC administration.

Exercise Intervention Outcomes with Cannabis Users and Nonusers Aged 60 and Older

Objectives: Cannabis use is increasing among older adults. We examined whether cannabis use impacted results of an intervention to increase physical activity in sedentary adults aged 60 and over. Methods: We measured differences in body mass index (BMI), exercise behavior, and cardiovascular fitness between older adult cannabis users (N = 28) and nonusers (N = 136) participating in an exercise intervention trial. Results: BMI of cannabis users was significantly lower than non-users (p = .007). Cannabis users reported .70 more days of exercise on the Stanford 7-Day Physical Activity Recall than non-users at the 8-week timepoint (p = .068) and were 4.1 points higher on the exercise subscale of the Community Healthy Activities Model Program for Seniors at 16-weeks (p = .045). Neither baseline nor post-intervention fitness differed by cannabis use status, and cardiovascular fitness improved after intervention in the full sample. Conclusion: These preliminary data suggest that current cannabis use status is not associated with a negative impact on fitness and efforts to increase exercise in sedentary older adults. Future studies should collect more detailed information on patterns and forms of cannabis use to understand their potential health effects for older adults.

An empirically derived method for measuring human gut microbiome alpha diversity: Demonstrated utility in predicting health-related outcomes among a human clinical sample

The human gut microbiome has emerged as a potential key factor involved in the manifestation of physical and mental health. Despite an explosion of cross-disciplinary interest in researching the gut microbiome, there remains to be a gold-standard method for operationalizing gut microbiome alpha diversity. Given researchers' interest in examining the relationships among gut microbiome alpha diversity and health-related outcomes of interest, a way of operationalizing the microbiome that yields a numeric value, which could be used in common statistical approaches, is needed. Thus, the current study aims to provide methodological guidance for how to operationalize microbiome alpha diversity. Findings suggest that alpha diversity of the human gut microbiome is comprised of two sub-constructs (richness and evenness), and we propose a step-by-step method of creating alpha diversity composite measures based on this key insight. Finally, we demonstrate that our empirically derived richness and evenness composite measures are significantly associated with health-related variables of interest (alcohol use, symptoms of depression) among a human clinical sample.

Acute Effects of Cannabis Concentrate on Motor Control and Speed: Smartphone-Based Mobile Assessment

Background: The use of cannabis concentrate is dramatically rising and sparking major safety concerns. Cannabis concentrate contains tetrahydrocannabinol (THC) potencies up to 90%, yet there has been little research on motor impairment after concentrate use (commonly referred to as "dabbing"). This study measured postural control and motor speed after the use of high potency concentrates in males and females. Methods: Experienced concentrate users (N = 65, Female: 46%, 17 ± 11 days/month of concentrate use) were assessed for motor performance in a mobile laboratory before, immediately after, and 1 h after ad-libitum cannabis concentrate use. Plasma levels of THC were obtained via venipuncture at each timepoint. We used a remotely deployable motor performance battery to assess arm and leg movement speed, index finger tapping rate, and balance. The sensors on a smart device (iPod Touch) attached to the participant provided quantitative measures of movement. Results: Arm speed slowed immediately after concentrate use and remained impaired after 1 h (p < 0.001), leg speed slowed 1 h after use (p = 0.033), and balance decreased immediately after concentrate use (eyes open: p = 0.017, eyes closed: p = 0.013) but not at 1 h post-use. These effects were not different between sexes and there was no effect of concentrate use on finger tapping speed. Acute changes in THC plasma levels after use of concentrates were minimally correlated with acute changes in balance performance. Conclusions: Use of cannabis concentrates in frequent users impairs movement speed and balance similarly in men and women. The motor impairment is largely uncorrelated with the change in THC plasma levels. These results warrant further refinement of cannabis impairment testing and encourage caution related to use of cannabis concentrates in work and driving settings.

DRD2 methylation is associated with executive control network connectivity and severity of alcohol problems among a sample of polysubstance users

Chronic exposure to alcohol and other drugs of abuse has been associated with deleterious consequences, including functional connectivity deficits within neural networks associated with executive control. Altered functional connectivity within the executive control network (ECN) might underlie the progressive inability to control consumption of alcohol and other drugs as substance use disorders progress. Genetic and epigenetic factors have been associated with substance use disorders (SUDs). For example, dopamine receptor 2 (DRD2) functioning has been associated with alcohol use disorder (AUD) and related phenotypes, including correlates of executive functioning. The present study aims to explore the relationship between a continuous measure of alcohol-related problems, epigenetic markers (methylation) within the DRD2 gene, and functional connectivity within the ECN among a sample of polysubstance users. A community sample of 658 subjects, whose consumption of alcohol, nicotine, and cannabis span across a spectrum of quantity and frequency of use, were obtained across previous studies in polysubstance using populations. Resting state functional magnetic resonance imaging was analyzed to identify intrinsic connectivity networks using a priori regions of interest. Methylation measurement of functionally relevant sites within the DRD2 gene was achieved via pyrosequencing. Regression-based models, including mediation and moderation models, tested the association between DRD2 methylation, functional connectivity within intrinsic neural networks (including the ECN), and severity of alcohol problems. Results suggest that average DRD2 methylation was negatively associated with right ECN (RECN) and left ECN (LECN) connectivity, but not associated with other networks tested, and DRD2 methylation was significantly associated with alcohol problems severity. Mediation models were not supported, although moderation models suggested that connectivity between edges within the RECN moderated the relationship between DRD2 methylation and AUD severity. Results support a theoretical model in which epigenetic factors are associated with neurobiological correlates of alcohol consumption among a sample of polysubstance users.

Investigating Relationships Between Alcohol and Cannabis Use in an Online Survey of Cannabis Users: A Focus on Cannabinoid Content and Cannabis for Medical Purposes

Cannabis is commonly used among people who drink alcohol, but findings are mixed regarding the direction of this relationship. The type of cannabis used [high-cannabidiol (CBD) vs. high-delta-9tetrahydrocannabinol (THC)] and motives for use (i.e., whether cannabis is used to treat a medical condition) may influence the relationship between cannabis and drinking. Specifically, CBD has shown preclinical promise in reducing alcohol consumption, and medical cannabis users report using cannabis to reduce drinking. This study leverages survey data from cannabis users who drink alcohol (N = 533). Respondents were categorized as using cannabis to treat (CTT) a medical condition or as individuals whose cannabis use is not intended to treat (NCTT) a medical condition and grouped based on the THC/CBD ratio of the flower or edible cannabis they typically use (e.g., "High-THC/CBD," "Medium-THC/CBD" and "Low-THC/CBD"). The CTT group (n = 412) reported drinking significantly less frequently than the NCTT group (n = 121). Cannabinoid content of flower cannabis was associated with alcohol consumed on cannabis-use days, such that individuals in the High-THC/CBD group drink more on cannabis-use days compared to the Medium-THC/CBD group. Cannabinoid content of edible cannabis was associated with drinks per drinking occasion, such that the High-THC/CBD group consumed the most drinks and the Low-THC/CBD group consumed the fewest. For both edible and flower groupings, higher-THC/CBD cannabis was associated with more frequent co-use than lower-THC/CBD cannabis. Results suggest that whether someone uses cannabis to treat a medical condition may impact their drinking frequency, and the cannabinoid content in flower and edible cannabis impacts alcohol consumption.

Cannabinoids and the Microbiota-Gut-Brain Axis: Emerging Effects of Cannabidiol and Potential Applications to Alcohol Use Disorders

The endocannabinoid system (ECS) has emerged in recent years as a potential treatment target for alcohol use disorders (AUD). In particular, the nonpsychoactive cannabinoid cannabidiol (CBD) has shown preclinical promise in ameliorating numerous clinical symptoms of AUD. There are several proposed mechanism(s) through which cannabinoids (and CBD in particular) may confer beneficial effects in the context of AUD. First, CBD may directly impact specific brain mechanisms underlying AUD to influence alcohol consumption and the clinical features of AUD. Second, CBD may influence AUD symptoms through its actions across the digestive, immune, and central nervous systems, collectively known as the microbiota-gut-brain axis (MGBA). Notably, emerging work suggests that alcohol and cannabinoids exert opposing effects on the MGBA. Alcohol is linked to immune dysfunction (e.g., chronic systemic inflammation in the brain and periphery) as well as disturbances in gut microbial species (microbiota) and increased intestinal permeability. These MGBA disruptions have been associated with AUD symptoms such as craving and impaired cognitive control. Conversely, existing preclinical data suggest that cannabinoids may confer beneficial effects on the gastrointestinal and immune system, such as reducing intestinal permeability, regulating gut bacteria, and reducing inflammation. Thus, cannabinoids may exert AUD harm-reduction effects, at least in part, through their beneficial actions across the MGBA. This review will provide a brief introduction to the ECS and the MGBA, discuss the effects of cannabinoids (particularly CBD) and alcohol in the brain, gut, and immune system (i.e., across the MGBA), and put forth a theoretical framework to inform future research questions.

Cannabis and Health Research: Rapid Progress Requires Innovative Research Designs

The United States has witnessed enormous changes concerning the acceptance of medicinal and recreational cannabis use. Sixty-three percent of the US population has access to medicinal cannabis markets, which offer increasingly diverse and potent cannabis products. Considering the rapidly changing cultural, political, and legal landscape, the scientific literature does not adequately inform public policy, medical decision making, or harm reduction approaches. The goals of this paper are to (1) investigate the state of cannabis research on medical conditions commonly treated with cannabis, (2) review the barriers that have led to large gaps between cannabis use and available empirical data, and (3) suggest a path forward with new research designs to address these gaps. Thus, we aim to advance a more nuanced understanding of the barriers to cannabis research and suggest innovative research designs necessary for rapid development of a meaningful knowledge base.

Cannabinoids, Pain, and Opioid Use Reduction: The Importance of Distilling and Disseminating Existing Data

The high prevalence of chronic pain conditions combined with an over-reliance on opioid prescriptions has resulted in an opioid epidemic and a desperate need for solutions. There is some debate about whether cannabis might play a role in addressing chronic pain conditions as well as the opioid epidemic. Recent surveys suggest that a large number of people are using cannabis as a treatment for pain and to reduce use of opioids, and cannabis-derived products demonstrate at least modest efficacy in the treatment of pain in randomized controlled trials. In addition, surveillance studies from countries that have approved the use of Sativex, which is a cannabis-based product, have demonstrated that a combination of Δ9-tetrahydrocannabinol and cannabidiol has low potential for harm, is well tolerated, and is helpful to patients. Given the number of people in the United States who are already using cannabis to manage pain and opioid use in state-regulated markets, it is imperative to conduct additional research in these areas, and to disseminate information on how to minimize harm and maximize any benefits of using cannabinoids to mitigate pain and reduce opioid use. The purpose of this article is to call attention to the fact that cannabis is being used in the management of chronic pain. Thus, this article also provides a set of guidelines on how to approach using cannabis to treat pain.

An Overview and Proposed Research Framework for Studying Co-Occurring Mental- and Physical-Health Dysfunction

Mental- and physical-health conditions co-occur at a rate much higher than chance. Of patients who have a mental-health condition, more than half also have a physical disease, and these cases are associated with increased human suffering and societal cost. Comorbidity research to date has focused on co-occurring mental- and physical-health disorders separately, and relatively little research has examined the co-occurrence of mental- and physical-health dysfunction. In addition, even less is known about why mental- and physical-health dysfunction co-occurs or how to treat these cases. Thus, the aims of this article are to highlight the need for research at the intersection of physical- and mental-health dysfunction and to provide guidance on how to research cases of comorbidity. Toward these ends, we begin by presenting a selective overview of the possible role of biological processes in the co-occurrence of physical- and mental-health dysfunction using specific illustrative examples. Specifically, we outline how biological processes within the immune system and gastrointestinal system could underlie depression, irritable bowel syndrome, and their co-occurrence. We then advance and discuss a proposed research framework, including methodological and analytic guidance, that researchers could use when studying the phenomenon of co-occurring physical- and mental-health dysfunction.

Association between the oral microbiome and brain resting state connectivity in smokers

Recent studies have shown a critical role of the gastrointestinal microbiome in brain and behavior via the complex gut-microbiome-brain axis. However, the influence of the oral microbiome in neurological processes is much less studied, especially in response to the stimuli, such as smoking, within the oral microenvironment. Additionally, given the complex structural and functional networks in brain, our knowledge about the relationship between microbiome and brain function through specific brain circuits is still very limited. In this pilot study, we leveraged next generation sequencing for microbiome and functional neuroimaging technique to enable the delineation of microbiome-brain network links as well as their relationship to cigarette smoking. Thirty smokers and 30 age- and sex-matched nonsmokers were recruited for 16S sequencing of their oral microbial community. Among them, 56 subjects were scanned by resting-state functional magnetic resonance imaging to derive brain functional networks. Statistical analyses were performed to demonstrate the influence of smoking on the oral microbial composition, functional network connectivity, and the associations between microbial shifts and functional network connectivity alternations. Compared to nonsmokers, we found a significant decrease of beta diversity (P = 6 × 10^-3) in smokers and identified several classes (Betaproteobacteria, Spirochaetia, Synergistia, and Mollicutes) with significant alterations in microbial abundance. Pathway analysis on the predicted KEGG pathways shows that the microbiota with altered abundance are mainly involved in pathways related to cell processes, DNA repair, immune system, and neurotransmitters signaling. One brain functional network connectivity component was identified to have a significant difference between smokers and nonsmokers (P = 0.032), mainly including connectivity between brain default network and other task-positive networks. This brain functional component was also significantly associated with smoking related microbiota, suggesting a correlated cross-individual pattern between smoking-induced oral microbiome dysbiosis and brain functional connectivity alternation, possibly involving immunological and neurotransmitter signaling pathways. This work is the first attempt to link oral microbiome and brain functional networks, and provides support for future work in characterizing the role of oral microbiome in mediating smoking effects on brain activity.

DRD2 promoter methylation and measures of alcohol reward: functional activation of reward circuits and clinical severity

Studies have identified strong associations between D2 receptor binding potential and neural responses to rewarding stimuli and substance use. Thus, D2 receptor perturbations are central to theoretical models of the pathophysiology of substance dependence, and epigenetic changes may represent one of the fundamental molecular mechanisms impacting the effects of alcohol exposure on the brain. We hypothesized that epigenetic alterations in the promoter region of the dopamine D2 receptor (DRD2) gene would be associated with cue-elicited activation of neural reward regions, as well as severity of alcohol use behavior. The current study leveraged functional neuroimaging (fMRI) during an alcohol reward paradigm (n = 383) to test associations among DRD2 promoter methylation in peripheral tissue, signal change in the striatum during the presentation of alcohol cues, and severity of alcohol use disorder (AUD). Controlling for age, DRD2 promoter methylation was positively associated with responses to alcohol cues in the right accumbens (partial r = 0.144, P = 0.005), left putamen (partial r = 0.133, P = 0.009), right putamen (partial r = 0.106, P = 0.039), left caudate (partial r = 0.117, P = 0.022), and right caudate (partial r = 0.133, P = 0.009), suggesting that DRD2 methylation was positively associated with robust activation in the striatum in response to reward cues. DRD2 methylation was also positively associated with clinical metrics of AUD severity. Specifically, controlling for age, DRD2 methylation was associated with Alcohol Use Disorders Identification Test total (partial r = 0.140, P = 0.002); Impaired Control Scale total (partial r = 0.097, P = 0.044) and Alcohol Dependence Scale total (partial r = 0.152, P = 0.001). Thus, DRD2 methylation may be a critical mechanism linking D2 receptors with functional striatal brain changes and clinical severity among alcohol users.

The New Runner's High? Examining Relationships Between Cannabis Use and Exercise Behavior in States With Legalized Cannabis

Scientific literature examining cannabis use in the context of health behaviors, such as exercise engagement, is extremely sparse and has yielded inconsistent findings. This issue is becoming increasingly relevant as cannabis legalization continues, a situation that has been associated with increased initiation of use among adults, and increased potency of available products in legalized states. Physical activity is among the most important health behaviors, but many Americans do not meet minimum exercise recommendations for healthy living. Common issues surrounding low exercise rates include inadequate enjoyment of and motivation to exercise, and poor recovery from exercise. It is unclear whether cannabis use shortly before and/or after exercise impacts these issues, and whether this co-use affects exercise performance. The present online survey study examines attitudes and behaviors regarding cannabis use with exercise among adult cannabis users living in states with full legal access (N = 605). Results indicated that the majority (81.7%) of participants endorsed using cannabis concurrently with exercise, and those who did tended to be younger and more likely to be males (p < 0.0005 for both). Even after controlling for these differences, co-users reported engaging in more minutes of aerobic and anaerobic exercise per week (p < 0.01 and p < 0.05, respectively). In addition, the majority of participants who endorsed using cannabis shortly before/after exercise reported that doing so enhances their enjoyment of and recovery from exercise, and approximately half reported that it increases their motivation to exercise. This study represents an important step in clarifying cannabis use with exercise among adult users in states with legal cannabis markets, and provides guidance for future research directions.

Preliminary results from a pilot study examining brain structure in older adult cannabis users and nonusers

Exploring associations among cannabis use, brain structure, and cognitive function in older adults offers an opportunity to observe potential harm or benefit of cannabis. This pilot study assessed structural magnetic resonance imaging in older adults who were either current cannabis users (n = 28; mean age 69.8 years, 36% female) or nonusers (n = 28; mean age 66.8 years, 61% female). Recruitment targeted users who reported at least weekly use for at least the last year, although users had 23.55 years of regular cannabis use on average (SD=19.89, range 1.5-50 years). Groups were not significantly different in terms of sex, years of education, alcohol use, or anxiety symptoms, but were significantly different in age and depression symptoms. Users and nonusers did not differ in terms of total gray or white matter volumes controlling for age and depression symptoms, but users showed greater regional volume of left putamen, lingual cortex, and rostral middle frontal cortex. No significant differences between groups were observed in performance on a brief computerized cognitive battery. These results suggest that cannabis use likely does not have a widespread impact on overall cortical volume while controlling for age.

Neural mechanisms of risky decision making in adolescents reporting frequent alcohol and/or marijuana use

Because adolescence is a period of heightened exploration of new behaviors, there is a natural increase in risk taking including initial use of alcohol and marijuana. In order to better understand potential differences in neurocognitive functioning among adolescents who use drugs, the current study aimed to identify the neural substrates of risky decision making that differ among adolescents who are primary users of alcohol or marijuana, primary users of both alcohol and marijuana, and controls who report primary use of neither drug. Participants completed the Balloon Analogue Risk Task (BART) while undergoing functional magnetic resonance imaging. Comparison of brain activation during risky decisions versus non-risky decisions across all subjects revealed greater response to risky decisions in dorsal anterior cinguate cortex (dACC), anterior insula, ventral striatum, and lateral prefrontal cortex. Group comparisons across non-using controls, primary marijuana, primary alcohol, and alcohol and marijuana users revealed several notable differences in the recruitment of brain regions. Adolescents who use both alcohol and marijauna show decreased response during risky decision making compared to controls in insula, striatum, and thalamus, and reduced differentiation of increasing risk in dACC, insula, striatum, and superior parietal lobe compared to controls. These results provide evidence of differential engagement of risky decision making circuits among adolescents with varying levels of alcohol and marijuana use, and may provide useful targets for longitudinal studies that explicitly address causality of these differences.

Interactions between TLR4 methylation and alcohol consumption on subjective responses to an alcohol infusion

Aims

Converging evidence has implicated perturbed inflammatory signaling in alcohol use disorders (AUDs), and both animal and human studies suggest that alcohol-induced inflammatory signaling is mediated by Toll-Like Receptor 4 (TLR4). We previously demonstrated that TLR4 is hypermethylated in subjects with AUD compared to control individuals. Examining the relationship between TLR4 methylation and subjective alcohol responses could shed light on the role of TLR4 in promoting AUDs, thereby highlighting its potential as a treatment target.

Short summary

Significant interactions were demonstrated between Toll-like Receptor 4 (TLR4) methylation and human alcohol consumption patterns, such that greater methylation was associated with decreased positive and negative self-reported arousal during an alcohol infusion among light-to-moderate drinkers, but increased self-reported positive arousal and physiological arousal (i.e. systolic blood pressure) among heavy drinkers.

Methods

Latent growth models were used to examine the relationship between TLR4 methylation and subjective responses and physiological measures of arousal during an alcohol infusion across 222 drinkers.

Results

We observed significant interactions of TLR4 methylation and alcohol use (drinks per week) on intercepts for self-report and physiological arousal measures. Specifically, light-to-moderate drinkers had positive associations between methylation and stimulation and tension (r's = 0.21-0.24), and heavy drinkers had negative associations (r's = -0.15 to -0.21). There were also significant interaction effects on changes in tension (β = 0.31, P < 0.01), systolic blood pressure (β = 0.74, P < 0.01) and marginal effects on stimulation (β = 0.15, P = 0.07) during the infusion, such that methylation was associated with decreased arousal among light-to-moderate drinkers (r's = -0.12 to -0.25) but stable or increased arousal among heavy drinkers (r's = 0.05-0.19).

Conclusions

Findings suggest that the relationship between TLR4 methylation and subjective and physiological arousal during acute alcohol intoxication depends upon on self-reported alcohol use. These data demonstrate the influence of TLR4 on subjective responses to alcohol, thereby supporting the need for further research on its potential as a pharmacological treatment target.

Exploring cannabis concentrates on the legal market: User profiles, product strength, and health-related outcomes

Background

Concentrated cannabis products are increasingly available and used, particularly in states with legal cannabis, but little is known about the profiles and characteristics of concentrate users. We aimed to characterize user profiles of cannabis users living in states with legal medical or recreational cannabis who reported using concentrates to those who do not use concentrates.

Methods

An anonymous online survey was advertised in California, Colorado, Nevada, Oregon, and Washington. We compared respondents who endorsed frequent concentrate use (FC; N = 67) (i.e. 4 days/week) with cannabis users who never use concentrates (NC; N = 64), and with those who smoke/vaporize cannabis flower frequently but never or very rarely use concentrates (FF; N = 60), on measures related to cannabis use patterns and cannabinoid product strength, other substance use, and occupational functioning and health.

Results

FC endorsed more symptoms of cannabis use disorder as compared to non-concentrate users (p < 0.05), but were similar to FF and NC on other health and occupational outcomes. FC also differed from FF and NC in that they tended to use cannabis that was higher in THC (p < 0.0005), even when using non-concentrated forms of cannabis (p < 0.005). Over half of FC users reported typically using concentrates of at least 80% THC, and 21% endorsed use of (non-concentrated) dry cannabis flower containing at least 30% THC.

Conclusions

Concentrate users endorsed higher symptoms of cannabis use disorder and use higher strength cannabis even when using non-concentrated forms. Frequent use of concentrates may be associated with additional risks over and above frequent use of flower forms.

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Use of high potency concentrates is on the rise with little data on their impact.

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We compare profiles of concentrate users to users of other forms of cannabis.

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Concentrate users have more Cannabis Use Disorder symptoms.

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THC strengths are higher in concentrate users even when using other forms of cannabis.

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Concentrates may pose greater abuse risk relative to other forms of cannabis.

Development, Initial Testing and Challenges of an Ecologically Valid Reward Prediction Error FMRI Task for Alcoholism

Aims

To advance translational studies of the role of reward prediction error (PE) in alcohol use disorder, the present study sought to develop and conduct an initial test of an alcohol-specific PE task paradigm using functional magnetic resonance imaging in humans.

Methods

Alcohol dependent or social drinkers received small tastes of their preferred alcohol beverage or control beverage, with preceding visual cues indicating whether alcohol (or water) would be delivered. To assess both positive and negative PE signals, expectancies were systematically violated in both positive (i.e. expecting water and receiving alcohol) and negative (i.e. expecting alcohol and receiving water) directions. Exploratory trial-by-trial analyses were conducted to explore temporal fluctuations of activation within a priori-defined regions of interest that have been implicated in cue reactivity and PE processing.

Results

Across the entire sample of participants, positive PE-related brain activation was found in a large cluster comprised of frontal lobe regions, as well as insular cortex, and motor/sensory cortices. Compared to social drinking subjects, alcohol dependent subjects had greater positive PE-related brain activity in left superior parietal lobule, lateral occipital cortex and postcentral gyrus. Exploratory trial-by-trial analyses indicated differences in activation specific to type of taste, mostly at earlier trials.

Conclusions

This task-development oriented pilot study found that PE signaling may not be detected in expected brain regions when image analyses average across all PE trials of the task. Rather, a trial-by-trial analysis approach may help detect sparse, temporally distinct PE signaling in expected reward processing regions.

Short Summary

This fMRI study of reward prediction error found greater positive prediction error-related activity (i.e. expecting water taste, receiving alcohol taste) in alcohol dependent individuals relative to social drinkers in parietal and occipital cortices. Trial-by-trial analyses may be able to better detect sparse prediction error signaling in expected reward processing regions.

TLR4 Methylation Moderates the Relationship Between Alcohol Use Severity and Gray Matter Loss

OBJECTIVE

Alcohol use disorders (AUDs) are associated with decreased gray matter, and neuroinflammation is one mechanism through which alcohol may confer such damage, given that heavy alcohol use may promote neural damage via activation of toll-like receptor 4 (TLR4)-mediated inflammatory signaling cascades. We previously demonstrated that TLR4 is differentially methylated in AUD compared with control subjects, and the present study aims to extend this work by examining whether TLR4 methylation moderates the relationship between alcohol use and gray matter.

METHOD

We examined TLR4 methylation and gray matter thickness in a large sample (N = 707; 441 males) of adults (ages 18-56) reporting a range of AUD severity (mean Alcohol Use Disorders Identification Test score = 13.18; SD = 8.02). We used a series of ordinary least squares multiple regression equations to regress gray matter in four bilateral brain regions (precuneus, lateral orbitofrontal, inferior parietal, and superior temporal) on alcohol use, TLR4 methylation, and their interaction, controlling for demographic, psychological, and other substance use variables.

RESULTS

After we corrected for multiple tests, a significant Alcohol × TLR4 Methylation interaction emerged in the equations modeling left precuneus and right inferior parietal gray matter. Follow-up analyses examining the nature of these interactions demonstrated a significant negative association between alcohol and precuneus and inferior parietal gray matter in individuals with low TLR4 methylation, but no relationship between alcohol and gray matter in the high methylation group.

CONCLUSIONS

These findings suggest that TLR4 methylation may be protective against the damage conferred by alcohol on precuneus and inferior parietal gray matter, thereby implicating TLR4 for further investigation as a possible AUD treatment target.

The Impact of Combinations of Alcohol, Nicotine, and Cannabis on Dynamic Brain Connectivity

Alcohol, nicotine, and cannabis are among the most commonly used drugs. A prolonged and combined use of these substances can alter normal brain wiring in different ways depending on the consumed cocktail mixture. Brain connectivity alterations and their change with time can be assessed using functional magnetic resonance imaging (fMRI) because of its spatial and temporal content. Here, we estimated dynamic functional network connectivity (dFNC) as derived from fMRI data to investigate the effects of single or combined use of alcohol, nicotine, and cannabis. Data from 534 samples were grouped according to their substance use combination as controls (CTR), smokers (SMK), drinkers (DRN), smoking-and-drinking subjects (SAD), marijuana users (MAR), smoking-and-marijuana users (SAM), marijuana-and-drinking users (MAD), and users of all three substances (ALL). The DRN group tends to exhibit decreased connectivity mainly in areas of sensorial and motor control, a result supported by the dFNC outcome and the alcohol use disorder identification test. This trend dominated the SAD group and in a weaker manner MAD and ALL. Nicotine consumers were characterized by an increment of connectivity between dorsal striatum and sensorimotor areas. Where possible, common and separate effects were identified and characterized by the analysis of dFNC data. Results also suggest that a combination of cannabis and nicotine have more contrasting effects on the brain than a single use of any of these substances. On the other hand, marijuana and alcohol might follow an additive effect trend. We concluded that all of the substances have an impact on brain connectivity, but the effect differs depending on the dFNC state analyzed.

A Novel Observational Method for Assessing Acute Responses to Cannabis: Preliminary Validation Using Legal Market Strains

Background: The development of novel cannabis research methods that are compatible with current federal regulations is imperative to conduct studies of the effects of legal market cannabis. There is very little research on higher strength, higher Δ9-tetrahydrocannabinol (THC), which has become increasingly available since legalization. Research on strains containing cannabidiol (CBD), a second primary, but nonpsychotomimetic, cannabinoid, is very limited. Materials and Methods: Using a novel observational methodology, regular cannabis users were asked to use one of two legal market cannabis strains that they purchased from a local dispensary (one strain containing 8% THC and 16% CBD (THC+CBD) and one containing a 17% THC concentration, but no CBD (THC). After using their suggested cannabis strain as they typically would for a 3-day period, participants returned to the laboratory immediately after their final use. Measures included a blood draw to measure cannabinoid blood levels and circulating cytokines, self-reported subjective drug effects, and verbal recall memory. Results: Analysis of CBD/THC concentration levels in the blood following the 3-day strain manipulation suggests that all, but one participant (n=23/24) followed instructions and used their assigned strain. Individuals in the THC group (n=11) smoked no more than their usual amount, and participants who used the THC+CBD (n=12) strain smoked more than their reported usual amount, but did not have significantly different THC+metabolite blood levels from the THC group. The THC+CBD strain was also associated with less desire to smoke, lower levels of subjective drug effects, and lower levels of circulating cytokines (TNF-α, IL-6, and IL-1β) immediately after use. Conclusions: Initial results support the feasibility of this novel observational methodology involving brief manipulation of strain use. Preliminary findings indicate that participants may self-titrate cannabis use based on cannabinoid concentration and the THC+CBD strain was associated with lower levels of cannabis craving, subjective intoxication, and circulating cytokines.

Investigating the Relationships Between Alcohol Consumption, Cannabis Use, and Circulating Cytokines: A Preliminary Analysis

BACKGROUND

In recent years, human and animal studies have converged to support altered inflammatory signaling as a molecular mechanism underlying the pathophysiology of alcohol use disorders (AUDs). Alcohol binds to receptors on immune cells, triggering signaling pathways that produce pro-inflammatory cytokines. Chronic inflammation is associated with tissue damage, which may contribute to negative effects of AUD. Conversely, cannabis is associated with decreased inflammatory signaling, and animal studies suggest that cannabinoids may impact alcohol-induced inflammation. Thus, the impact of cannabis on inflammation in AUDs in humans warrants examination.

METHODS

We explored the relationship between self-reported alcohol and cannabis use and circulating levels of the pro-inflammatory cytokines interleukin 6 (IL-6), IL-8, and IL-1β in the blood. Among 66 regular drinkers (mean age = 30.08), we examined circulating cytokines and administered questionnaires assessing alcohol consumption and days of cannabis use over the past 90 days. We examined whether alcohol consumption, cannabis use, and gender were associated with changes in circulating cytokines, and whether there was a significant interaction between alcohol and cannabis use predicting blood levels of circulating cytokines.

RESULTS

A positive association between alcohol and IL-6 emerged. We also observed a negative association between cannabis and IL-1β. Follow-up moderation analyses indicated a cannabis by alcohol interaction predicting circulating IL-6, such that cannabis nonusers showed a stronger relationship between alcohol and IL-6 compared to cannabis users.

CONCLUSIONS

These preliminary findings suggest that cannabinoid compounds may serve to mitigate inflammation associated with alcohol use. In addition, the present results provide data to inform future investigations, with the goal of ultimately leveraging knowledge of the role of inflammation in AUDs to develop more effective treatments focused on novel immune targets.

Default mode network deactivation to smoking cue relative to food cue predicts treatment outcome in nicotine use disorder

Identifying predictors of treatment outcome for nicotine use disorders (NUDs) may help improve efficacy of established treatments, like varenicline. Brain reactivity to drug stimuli predicts relapse risk in nicotine and other substance use disorders in some studies. Activity in the default mode network (DMN) is affected by drug cues and other palatable cues, but its clinical significance is unclear. In this study, 143 individuals with NUD (male n = 91, ages 18-55 years) received a functional magnetic resonance imaging scan during a visual cue task during which they were presented with a series of smoking-related or food-related video clips prior to randomization to treatment with varenicline (n = 80) or placebo. Group independent components analysis was utilized to isolate the DMN, and temporal sorting was used to calculate the difference between the DMN blood-oxygen-level dependent signal during smoke cues and that during food cues for each individual. Food cues were associated with greater deactivation compared with smoke cues in the DMN. In correcting for baseline smoking and other clinical variables, which have been shown to be related to treatment outcome in previous work, a less positive Smoke - Food difference score predicted greater smoking at 6 and 12 weeks when both treatment groups were combined (P = 0.005, β = -0.766). An exploratory analysis of executive control and salience networks demonstrated that a more positive Smoke - Food difference score for executive control network predicted a more robust response to varenicline relative to placebo. These findings provide further support to theories that brain reactivity to palatable cues, and in particular in DMN, may have a direct clinical relevance in NUD.

Opposite Epigenetic Associations With Alcohol Use and Exercise Intervention

Alcohol use disorder (AUD) is a devastating public health problem in which both genetic and environmental factors play a role. Growing evidence supports that epigenetic regulation is one major mechanism in neuroadaptation that contributes to development of AUD. Meanwhile, epigenetic patterns can be modified by various stimuli including exercise. Thus, it is an intriguing question whether exercise can lead to methylation changes that are opposite to those related to drinking. We herein conducted a comparative study to explore this issue. Three cohorts were profiled for DNA methylation (DNAm), including a longitudinal exercise intervention cohort (53 healthy participants profiled at baseline and after a 12-months exercise intervention), a cross-sectional case-control cohort (81 hazardous drinkers and 81 healthy controls matched in age and sex), and a cross-sectional binge drinking cohort (281 drinkers). We identified 906 methylation sites showing significant DNAm differences between drinkers and controls in the case-control cohort, as well as, associations with drinking behavior in the drinking cohort. In parallel, 341 sites were identified for significant DNAm alterations between baseline and follow-up in the exercise cohort. Thirty-two sites overlapped between these two set of findings, of which 15 sites showed opposite directions of DNAm associations between exercise and drinking. Annotated genes of these 15 sites were enriched in signaling pathways related to synaptic plasticity. In addition, the identified methylation sites significantly associated with impaired control over drinking, suggesting relevance to neural function. Collectively, the current findings provide preliminary evidence that exercise has the potential to partially reverse DNAm differences associated with drinking at some CpG sites, motivating rigorously designed longitudinal studies to better characterize epigenetic effects with respect to prevention and intervention of AUD.

Structural neuroimaging correlates of alcohol and cannabis use in adolescents and adults

BACKGROUND AND AIMS

Chronic alcohol use is associated with lower gray matter volume, and we reported recently that alcohol use showed negative associations with widespread gray matter (GM) volume even among young adults. The current study aimed to test the strength of association between (1) alcohol use and GM volume; (2) alcohol use and white matter (WM) integrity; (3) cannabis use and GM volume; and (4) cannabis use and WM integrity among adults and adolescents.

DESIGN AND SETTING

General linear models within large pooled cross-sectional samples of adolescents and adults who had participated in studies collecting substance use and neuroimaging data in the southwestern United States.

PARTICIPANTS

The current analysis included adults aged 18-55 years (n = 853) and adolescents aged 14-18 years (n = 439) with a range of alcohol and cannabis use.

MEASUREMENTS

The dependent variable was GM volume or WM integrity, with key predictors of alcohol use [Alcohol Use Disorders Identification Test (AUDIT) score] and cannabis use (past 30-day use).

FINDINGS

Alcohol use showed large clusters of negative associations (η_p²  = 0.028-0.145, P < 0.001) with GM volume among adults and to a lesser extent (one cluster; η_p²  = 0.070, P < 0.05) among adolescents. Large clusters showed significant associations (η_p²  = 0.050-0.124, P < 0.001) of higher alcohol use with poorer WM integrity, whereas adolescents showed no significant associations between alcohol use and WM. No associations were observed between structural measures and past 30-day cannabis use in adults or adolescents.

CONCLUSIONS

Alcohol use severity is associated with widespread lower gray matter volume and white matter integrity in adults, and with lower gray matter volume in adolescents.

Moderators of smoking cessation outcomes in a randomized-controlled trial of varenicline versus placebo

RATIONALE AND OBJECTIVE

Varenicline has gained a reputation as the optimal intervention for treatment resistant smokers, yet more than half of those who try it do not succeed. To better understand individual differences in the effectiveness of varenicline, this study evaluates the effectiveness of varenicline for smoking cessation in a double-blind, placebo-controlled, randomized clinical trial and examines the influence of psychological factors on treatment outcome.

METHOD

Two hundred five cigarette smokers interested in quitting were randomly assigned to 12 weeks of varenicline or placebo. Outcomes examined were CO-confirmed continuous abstinence for the past month, average number of cigarettes smoked per day, and 7-day point prevalence.

RESULTS

Varenicline-treated participants were more likely than placebo to achieve continuous abstinence at the end of treatment (OR = 3.29; RR = 2.62), and 7-day point prevalence rates showed an effect of medication at each time point. Participants in both groups significantly reduced their smoking during the course of treatment and follow-up, and the medication by visit interaction was significant in the expected direction. Impulsivity and personality style emerged as moderators of the relationship between medication condition and treatment outcome.

CONCLUSIONS

In addition to replicating efficacy results for varenicline versus placebo, the present study shows that the efficacy of pharmacotherapy is influenced by psychological factors. In an era where pharmacotherapy is often perceived as the "silver bullet," we are reminded that smoking cessation is a dynamic process and intervention must be adaptable to address individual differences.

Functional network connectivity predicts treatment outcome during treatment of nicotine use disorder

Altered resting state functional connectivity (rsFC) and functional network connectivity (FNC), which is a measure of coherence between brain networks, may be associated with nicotine use disorder (NUD). We hypothesized that higher connectivity between insula and 1) dorsal anterior cingulate cortex (dACC) and 2) dorsolateral prefrontal cortex (dlPFC) would predict better treatment outcomes. We also performed an exploratory analysis of the associations between FNC values between additional key frontal and striatal regions and treatment outcomes. One hundred and forty four individuals with NUD underwent a resting state session during functional MRI prior to randomization to treatment with varenicline (n=82) or placebo. Group independent component analysis (ICA) was utilized to extract individual subject components and time series from intrinsic connectivity networks in aforementioned regions, and FNC between all possible pairs were calculated. Higher FNC between insula and dACC (rho=0.21) was significantly correlated with lower levels of baseline smoking quantity but did not predict treatment outcome upon controlling for baseline smoking. Higher FNC between putamen and dACC, caudate and dACC, and caudate and dlPFC significantly predicted worse treatment outcome in participants reporting high subjective withdrawal before the scan. FNC between key regions hold promise as biomarkers to predict outcome in NUD.

Body mass is positively associated with neural response to sweet taste, but not alcohol, among drinkers

Obesity is a large and growing public health concern, presenting enormous economic and health costs to individuals and society. A burgeoning literature demonstrates that overweight and obese individuals display different neural processing of rewarding stimuli, including caloric substances, as compared to healthy weight individuals. However, much extant research on the neurobiology of obesity has focused on addiction models, without highlighting potentially separable neural underpinnings of caloric intake versus substance use. The present research explores these differences by examining neural response to alcoholic beverages and a sweet non-alcoholic beverage, among a sample of individuals with varying weight status and patterns of alcohol use and misuse. Participants received tastes of a sweet beverage (litchi juice) and alcoholic beverages during fMRI scanning. When controlling for alcohol use, elevated weight status was associated with increased activation in response to sweet taste in regions including the cingulate cortex, hippocampus, precuneus, and fusiform gyrus. However, weight status was not associated with neural response to alcoholic beverages.

Compromised External Validity: Federally Produced Cannabis Does Not Reflect Legal Markets

As the most widely used illicit drug worldwide, and as a source of numerous under-studied pharmacologically-active compounds, a precise understanding of variability in psychological and physiological effects of Cannabis varieties is essential. The National Institute on Drug Abuse (NIDA) is designated as the sole legal producer of Cannabis for use in US research studies. We sought to compare the chemical profiles of Cannabis varieties that are available to consumers in states that have state-legalized use versus what is available to researchers interested in studying the plant and its effects. Our results demonstrate that the federally-produced Cannabis has significantly less variety and lower concentrations of cannabinoids than are observed in state-legal U.S. dispensaries. Most dramatically, NIDA’s varieties contain only 27% of the THC levels and as much as 11–23 times the Cannabinol (CBN) content compared to what is available in the state-legal markets. Research restricted to using the current range of federally-produced Cannabis thus may yield limited insights into the chemical, biological and pharmacological properties, and medical potential of material that is available in the state markets. Investigation is urgently needed on the full diversity of Cannabis chemotypes known to be available to the public.