Co-exposure of cannabinoids with amphetamines and biological, behavioural and health outcomes: a scoping review of animal and human studies

Analysis of animal-to-human translation shows that only 5% of animal-tested therapeutic interventions obtain regulatory approval for human applications

There is an ongoing debate about the value of animal experiments to inform medical practice, yet there are limited data on how well therapies developed in animal studies translate to humans. We aimed to assess 2 measures of translation across various biomedical fields: (1) The proportion of therapies which transition from animal studies to human application, including involved timeframes; and (2) the consistency between animal and human study results. Thus, we conducted an umbrella review, including English systematic reviews that evaluated the translation of therapies from animals to humans. Medline, Embase, and Web of Science Core Collection were searched from inception until August 1, 2023. We assessed the proportion of therapeutic interventions advancing to any human study, a randomized controlled trial (RCT), and regulatory approval. We meta-analyzed the concordance between animal and human studies. The risk of bias was probed using a 10-item checklist for systematic reviews. We included 122 articles, describing 54 distinct human diseases and 367 therapeutic interventions. Neurological diseases were the focus of 32% of reviews. The overall proportion of therapies progressing from animal studies was 50% to human studies, 40% to RCTs, and 5% to regulatory approval. Notably, our meta-analysis showed an 86% concordance between positive results in animal and clinical studies. The median transition times from animal studies were 5, 7, and 10 years to reach any human study, an RCT, and regulatory approval, respectively. We conclude that, contrary to widespread assertions, the rate of successful animal-to-human translation may be higher than previously reported. Nonetheless, the low rate of final approval indicates potential deficiencies in the design of both animal studies and early clinical trials. To ameliorate the efficacy of translating therapies from bench to bedside, we advocate for enhanced study design robustness and the reinforcement of generalizability.

Evaluation of the immune system status and hematological dyscrasias, among amphetamine and cannabis abusers at Eradah Hospital in Qassim, Saudi Arabia

This cross-sectional study aims to evaluate the immune system status and hematological disturbances among individuals who abuse amphetamines and cannabis. Substance abuse, particularly of amphetamines and cannabis, has been associated with various adverse effects on the body, including potential impacts on the immune system and hematological parameters. However, limited research has been conducted to comprehensively assess these effects in a cross-sectional design. Additionally, fungal infections are on the rise internationally, and immune-compromised people are particularly susceptible. The study will recruit a sample of amphetamine and cannabis abusers (n = 50) at the Eradah Hospital in the Qassim Region of Buraydah and assess their sociodemographic and biochemical variables, including blood indices and differential WBC indices, liver, and kidney profiles. Additionally, 50 sputum samples in total were cultured for testing for fungus infections. To obtain the descriptive statistics, the data was imported into Microsoft Excel and subjected to statistical analysis using SPSS 22.0. Amphetamine and cannabis abuser's sociodemographic variables analysis observed that the majority (52%) were aged 18-30, with 56% in secondary school. Unemployment was a significant issue, and most had no other health issues. The majority (50%) had 5-10 years of abuse, while 32% had less than 5 years, and only 18% had been drug abusers for more than 10 years. There were significant changes (p < 0.001) in all different leukocyte blood cells, including neutrophils, lymphocytes, monocytes, eosinophils, and basophils. Furthermore, a microscopic examination of blood films from individuals who misuse the combination of the medications "amphetamine and cannabis" reveals hazardous alterations in Neutrophils. Out of 50, 35 sputum samples showed positive growth on Sabouraud dextrose agar (SDA) with chloramphenicol antibiotic, indicating a unicellular fungal growth. The present study explores the immune system and hematological disturbances linked to amphetamine and cannabis abuse, providing insights into health risks and targeted interventions. The findings complement previous research on drug users' hematological abnormalities, particularly in white blood cells. Routine hematological tests help identify alterations in homeostatic conditions, improving patient knowledge and preventing major issues. Further research is needed on multi-drug abuse prevention, early detection, and intervention. The cross-sectional design allows for a snapshot of the immune system and hematological status among abusers, laying the groundwork for future longitudinal studies. Key Words: Drug Effect, Immunity, Epidemiology, Oxidative Stress, Inflammation.

Cannabis use to manage stimulant cravings among people who use unregulated drugs

BACKGROUND

We sought to analyze the association between cannabis use to manage stimulant cravings and self-reported changes in stimulant use among structurally marginalized people who use unregulated drugs (PWUD).

METHODS

The data for this secondary analysis was collected from a cross-sectional questionnaire administered to people who concurrently use cannabis and unregulated stimulants in Vancouver, Canada. We used logistic regression models to analyze the association between cannabis use to manage stimulant cravings and self-reported changes in the frequency of stimulant use.

RESULTS

In total, 297 individuals were included in the present study. Cannabis use to manage stimulant cravings was reported by 134 (45.1 %) participants and 104 (77.6 %) of these participants reported decreasing their stimulant use during periods of cannabis use. In the multivariable logistic regression analysis, cannabis use to manage stimulant cravings (adjusted Odds Ratio [aOR] = 0.24, 95 % confidence interval [CI]: 0.10, 0.56) was significantly associated with self-reported reductions in stimulant use. In the sub-analyses, cannabis use to manage stimulant cravings was significantly associated with reduced stimulant use among people who used crystal methamphetamine daily (aOR = 0.08, 95 % CI: 0.02-0.37) and was not significantly associated with reduced stimulant use among people who used crack/cocaine daily (aOR = 0.33, 95 % CI: 0.04-2.86).

CONCLUSIONS

These findings indicate that cannabis use to manage stimulant cravings is a common harm reduction strategy and suggest that this may be an effective strategy to reduce stimulant use among some PWUD.

Cannabis use may attenuate neurocognitive performance deficits resulting from methamphetamine use disorder

OBJECTIVE

Methamphetamine and cannabis are two widely used, and frequently co-used, substances with possibly opposing effects on the central nervous system. Evidence of neurocognitive deficits related to use is robust for methamphetamine and mixed for cannabis. Findings regarding their combined use are inconclusive. We aimed to compare neurocognitive performance in people with lifetime cannabis or methamphetamine use disorder diagnoses, or both, relative to people without substance use disorders.

METHOD

423 (71.9% male, aged 44.6 ± 14.2 years) participants, stratified by presence or absence of lifetime methamphetamine (M-/M+) and/or cannabis (C-/C+) DSM-IV abuse/dependence, completed a comprehensive neuropsychological, substance use, and psychiatric assessment. Neurocognitive domain T-scores and impairment rates were examined using multiple linear and binomial regression, respectively, controlling for covariates that may impact cognition.

RESULTS

Globally, M+C+ performed worse than M-C- but better than M+C-. M+C+ outperformed M+C- on measures of verbal fluency, information processing speed, learning, memory, and working memory. M-C+ did not display lower performance than M-C- globally or on any domain measures, and M-C+ even performed better than M-C- on measures of learning, memory, and working memory.

CONCLUSIONS

Our findings are consistent with prior work showing that methamphetamine use confers risk for worse neurocognitive outcomes, and that cannabis use does not appear to exacerbate and may even reduce this risk. People with a history of cannabis use disorders performed similarly to our nonsubstance using comparison group and outperformed them in some domains. These findings warrant further investigation as to whether cannabis use may ameliorate methamphetamine neurotoxicity.

The Combined Effects of Cannabis, Methamphetamine, and HIV on Neurocognition

OBJECTIVE

Methamphetamine and cannabis are two widely used substances among people living with HIV (PLWH). Whereas methamphetamine use has been found to worsen HIV-associated neurocognitive impairment, the effects of combined cannabis and methamphetamine use disorder on neurocognition in PLWH are not understood. In the present study, we aimed to determine the influence of these substance use disorders on neurocognition in PLWH and to explore if methamphetamine-cannabis effects interacted with HIV status.

METHOD AND PARTICIPANTS

After completing a comprehensive neurobehavioral assessment, PLWH (n = 472) were stratified by lifetime methamphetamine (M-/M+) and cannabis (C-/C+) DSM-IV abuse/dependence disorder into four groups: M-C- (n = 187), M-C+ (n = 68), M+C-, (n = 82), and M+C+ (n = 135). Group differences in global and domain neurocognitive performances and impairment were examined using multiple linear and logistic regression, respectively, while holding constant other covariates that were associated with study groups and/or cognition. Data from participants without HIV (n = 423) were added, and mixed-effect models were used to examine possible interactions between HIV and substance use disorders on neurocognition.

RESULTS

Compared with M+C+, M+C- performed worse on measures of executive functions, learning, memory, and working memory and were more likely to be classified as impaired in those domains. M-C- performed better than M+C+ on measures of learning and memory but worse than M-C+ on measures of executive functions, learning, memory, and working memory. Detectable plasma HIV RNA and nadir CD4 < 200 were associated with lower overall neurocognitive performance, and these effects were greater for M+C+ compared with M-C-.

CONCLUSIONS

In PLWH, lifetime methamphetamine use disorder and both current and legacy markers of HIV disease severity are associated with worse neurocognitive outcomes. There was no evidence of an HIV × M+ interaction across groups, but neurocognition was most impacted by HIV among those with polysubstance use disorder (M+C+). Better performance by C+ groups is consistent with findings from preclinical studies that cannabis use may protect against methamphetamine's deleterious effects.

Does chronic use of amphetamine-type stimulants impair interference control? - A meta-analysis

In substance use and addiction, inhibitory control is key to ignoring triggers, withstanding craving and maintaining abstinence. In amphetamine-type stimulant (ATS) users, most research focused on behavioral inhibition, but largely neglected the equally important subdomain of cognitive interference control. Given its crucial role in managing consumption, we investigated the relationship between interference control and chronic ATS use in adults. A database search (Pubmed & Web of Science) and relevant reviews were used to identify eligible studies. Effect sizes were estimated with random effects models. Subgroup, meta-regression, and sensitivity analyses explored heterogeneity in effect sizes. We identified 61 studies (53 datasets) assessing interference control in 1873 ATS users and 1905 controls. Findings revealed robust small effect sizes for ATS-related deficits in interference control, which were mainly seen in methamphetamine, as compared to MDMA users. The differential effects are likely due to tolerance-induced dopaminergic deficiencies (presumably most pronounced in methamphetamine users). Similarities between different ATS could be due to noradrenergic deficiencies; but elucidating their functional role in ATS users requires further/more research.

Nanowired Delivery of Mesenchymal Stem Cells with Antioxidant Compound H-290/51 Reduces Exacerbation of Methamphetamine Neurotoxicity in Hot Environment

Military personnel are often exposed to hot environments either for combat operations or peacekeeping missions. Hot environment is a severe stressful situation leading to profound hyperthermia, fatigue and neurological impairments. To avoid stressful environment, some people frequently use methamphetamine (METH) or other psychostimulants to feel comfortable under adverse situations. Our studies show that heat stress alone induces breakdown of the blood-brain barrier (BBB) and edema formation associated with reduced cerebral blood flow (CBF). On the other hand, METH alone induces hyperthermia and neurotoxicity. These effects of METH are exacerbated at high ambient temperatures as seen with greater breakdown of the BBB and brain pathology. Thus, a combination of METH use at hot environment may further enhance the brain damage-associated behavioral dysfunctions. METH is well known to induce severe oxidative stress leading to brain pathology. In this investigation, METH intoxication at hot environment was examined on brain pathology and to explore suitable strategies to induce neuroprotection. Accordingly, TiO₂-nanowired delivery of H-290/51 (150 mg/kg, i.p.), a potent chain-breaking antioxidant in combination with mesenchymal stem cells (MSCs), is investigated in attenuating METH-induced brain damage at hot environment in model experiments. Our results show that nanodelivery of H-290/51 with MSCs significantly enhanced CBF and reduced BBB breakdown, edema formation and brain pathology following METH exposure at hot environment. These observations are the first to point out that METH exacerbated brain pathology at hot environment probably due to enhanced oxidative stress, and MSCs attenuate these adverse effects, not reported earlier.