Cognitive motor deficits in cannabis users

Using Smartphone Technology to Track Real-Time Changes in Anxiety/Depression Symptomatology Among Florida Cannabis Users

Objective

Recent scientific attention has focused on the therapeutic effectiveness of cannabis use on a variety of physical and mental ailments. The present study uses smartphone technology to assess self-reported experiences of Florida cannabis users to understand how cannabis may impact anxiety and depression symptomatology.

Method

Several hundred Releaf App™ users from the state of Florida provided anonymous, real-time reports of their symptoms of anxiety and/or depression immediately before and after cannabis use sessions. Linear mixed-effects modeling was used to analyze the data at the symptom and user level.

Results

Results showed that for the majority of users, cannabis use was associated with a significant decrease in depression and anxiety symptomatology. While symptom type, doses per session, consumption method, and CBD levels were significant predictors of relief change, their effect sizes were small and should be interpreted with caution. At the user level, those who had positive relief outcomes in anxiety reported more doses and sessions, and those in the depression group reported more sessions.

Conclusions

Our results generally support the therapeutic effectiveness of cannabis against depression/anxiety symptomatology. Future work should include standardized statistics and effect size estimates for a better understanding of each variable's practical contribution to this area of study.

Marijuana Use, Vaping, and Preoperative Anesthetic and Surgical Considerations in Clinical Practice

In recent years, marijuana and vaping have acquired widespread popularity, with millions of people using them for a variety of reasons, including recreational purposes. However, these practices have often overlooked the implications on surgery and the preoperative anesthesia considerations. Marijuana can influence a patient's response to anesthesia, alter postoperative pain management, and increase the risk of complications, whereas vaping can have negative effects on the respiratory system and hinder the body's ability to recover after surgery.

Molecularly imprinted polymers (MIP) combined with Raman spectroscopy for selective detection of Δ⁹-tetrahydrocannabinol (THC)

A proof-of-concept sensor is developed for the sensitive and selective detection of Trans-Δ⁹-tetrahydrocannabinol (THC) based on a molecularly imprinted polymer (MIP) synthesized with a THC template which was analyzed using Raman spectroscopy to perform label-free monitoring of THC based on a single identifying Raman peak. The MIP sensor produced a peak at 1614 cm-1 in the Raman spectrum originating from the THC target molecule, allowing for the selective quantification of bound THC with the lowest detection limit of 250 ppm. A higher sensitivity of the MIP to the THC target molecule was observed compared to the non-imprinted polymer (NIP) control which confirmed the presence of THC-specific recognition sites within the synthesized MIP sensing material. The selectivity of this MIP-based sensor was determined by measuring the Raman spectrum of MIP exposed to Cannabidiol (CBD), ethanol, and acetone.

Cannabinoids, Endocannabinoids, and Synthetic Cannabimimetic Molecules in Neuromuscular Disorders

Neuromuscular disorders (NMDs) encompass a large heterogeneous group of hereditary and acquired diseases primarily affecting motor neurons, peripheral nerves, and the skeletal muscle system. The symptoms of NMDs may vary depending on the specific condition, but some of the most common ones include muscle weakness, pain, paresthesias, and hyporeflexia, as well as difficulties with swallowing and breathing. NMDs are currently untreatable. Therapeutic options include symptomatic and experimental medications aimed at delaying and alleviating symptoms, in some cases supplemented by surgical and physical interventions. To address this unmet medical need, ongoing research is being conducted on new treatments, including studies on medical cannabis, endocannabinoids, and related molecules with cannabimimetic properties. In this context, a significant amount of knowledge about the safety and effectiveness of cannabinoids in NMDs has been obtained from studies involving patients with multiple sclerosis experiencing pain and spasticity. In recent decades, numerous other preclinical and clinical studies have been conducted to determine the potential benefits of cannabinoids in NMDs. This review article aims to summarize and provide an unbiased point of view on the current knowledge about the use of cannabinoids, endocannabinoids, and synthetic analogs in NMDs, drawing from an array of compelling studies.

Chronic Δ9-tetrahydrocannabinol treatment has dose-dependent effects on open field exploratory behavior and [3H] SR141716A receptor binding in the rat brain

AIMS

Acute and chronic Δ⁹-THC exposure paradigms affect the body differently. More must be known about the impact of chronic Δ⁹-THC on cannabinoid-1 (CB1R) and mu-opioid (MOR) receptor levels in the brain. The present study examined chronic Δ⁹-THC's effects on CB1R and MOR levels and locomotor activity.

MAIN METHODS

Adolescent Sprague-Dawley rats were given daily intraperitoneal injections of Δ⁹-THC [0.75mg/kg (low dose or LD) or 2.0 mg/kg (high dose or HD)] or vehicle for 24 days, and locomotion in the open field was tested after the first and fourth weeks of chronic Δ⁹-THC exposure. Brains were harvested at the end of treatment. [³H] SR141716A and [³H] DAMGO autoradiography assessed CB1R and MOR levels, respectively.

KEY FINDINGS

Relative to each other, chronic HD rats showed reduced vertical plane (VP) entries and time, while LD rats had increased VP entries and time for locomotion, as assessed by open-field testing; no effects were found relative to the control. Autoradiography analyses showed that HD Δ⁹-THC significantly decreased CB1R binding relative to LD Δ⁹-THC in the cingulate (33%), primary motor (42%), secondary motor (33%) somatosensory (38%), rhinal (38%), and auditory (50%) cortices; LD Δ⁹-THC rats displayed elevated binding in the primary motor (33% increase) and hypothalamic (33 % increase) regions compared with controls. No significant differences were observed in MOR binding for the LD or HD compared to the control.

SIGNIFICANCE

These results demonstrate that chronic Δ⁹-THC dose-dependently altered CB1R levels throughout the brain and locomotor activity in the open field.

Machine Learning-Based Quantification of (-)-trans-Δ-Tetrahydrocannabinol from Human Saliva Samples on a Smartphone-Based Paper Microfluidic Platform

(-)-trans-Δ-Tetrahydrocannabinol (THC) is a major psychoactive component in cannabis. Despite the recent trends of THC legalization for medical or recreational use in some areas, many THC-driven impairments have been verified. Therefore, convenient, sensitive, quantitative detection of THC is highly needed to improve its regulation and legalization. We demonstrated a biosensor platform to detect and quantify THC with a paper microfluidic chip and a handheld smartphone-based fluorescence microscope. Microfluidic competitive immunoassay was applied with anti-THC-conjugated fluorescent nanoparticles. The smartphone-based fluorescence microscope counted the fluorescent nanoparticles in the test zone, achieving a 1 pg/mL limit of detection from human saliva samples. Specificity experiments were conducted with cannabidiol (CBD) and various mixtures of THC and CBD. No cross-reactivity to CBD was found. Machine learning techniques were also used to quantify the THC concentrations from multiple saliva samples. Multidimensional data were collected by diluting the saliva samples with saline at four different dilutions. A training database was established to estimate the THC concentration from multiple saliva samples, eliminating the sample-to-sample variations. The classification algorithms included k-nearest neighbor (k-NN), decision tree, and support vector machine (SVM), and the SVM showed the best accuracy of 88% in estimating six different THC concentrations. Additional validation experiments were conducted using independent validation sample sets, successfully identifying positive samples at 100% accuracy and quantifying the THC concentration at 80% accuracy. The platform provided a quick, low-cost, sensitive, and quantitative point-of-care saliva test for cannabis.

Remote detection of Cannabis-related impairments in performance?

RATIONALE

Researchers have traditionally studied the effects of psychoactive drugs such as Cannabis in controlled laboratory settings or relied on retrospective self-reports to measure impairment. However, advances in technology afford opportunities to conduct assessments remotely.

OBJECTIVES

We considered whether objective click-stream data (time and number of clicks spent on a webpage) during an online survey could supplement self-reports of substance use problems.

METHODS

The clickstream data of participants (n = 236) were examined as they completed an online study which included validated psychometric tests (Cannabis Use Disorders Identification Test-Revised, Grit-O, Kessler Psychological Distress Scale, and Brief Self Control Scale). Clickstream data were compared to self-reported Cannabis use.

RESULTS

People reporting Cannabis use within the last 4 weeks required more time and more clicks to complete the online survey, and this was specifically associated with reported frequency of use, duration of impairment, and problems with memory and concentration. Longer amounts of time and more clicks on the online questionnaire were associated with more recent Cannabis use rather than demographic factors or stimulant use.

CONCLUSIONS

These results imply clickstream data remotely detected indecision or other deficits associated with previous Cannabis use.

Chronic use of cannabis might impair sensory error processing in the cerebellum through endocannabinoid dysregulation

Chronic use of cannabis leads to both motor deficits and the downregulation of CB₁ receptors (CB₁R) in the cerebellum. In turn, cerebellar damage is often related to impairments in motor learning and control. Further, a recent motor learning task that measures cerebellar-dependent adaptation has been shown to distinguish well between healthy subjects and chronic cannabis users. Thus, the deteriorating effects of chronic cannabis use in motor performance point to cerebellar adaptation as a key process to explain such deficits. We review the literature relating chronic cannabis use, the endocannabinoid system in the cerebellum, and different forms of cerebellar-dependent motor learning, to suggest that CB₁R downregulation leads to a generalized underestimation and misprocessing of the sensory errors driving synaptic updates in the cerebellar cortex. Further, we test our hypothesis with a computational model performing a motor adaptation task and reproduce the behavioral effect of decreased implicit adaptation that appears to be a sign of chronic cannabis use. Finally, we discuss the potential of our hypothesis to explain similar phenomena related to motor impairments following chronic alcohol dependency.

Workplace Cannabis Policies: A Moving Target

Introduction: This article proposes a workplace cannabis policy paradigm that encompasses rapidly changing laws and regulations, legally defensible drug testing policies, and the needs of particular workplaces. Numerous states have now decriminalized medical or recreational use of cannabis, although U.S. federal law still defines cannabis as a Schedule I substance with no currently accepted medical use and a high potential for abuse. For employers and employees, the confusion generated by this contradiction is exacerbated by the widely varying effects of the available cannabis delivery systems, the primitive and cumbersome drug testing protocols often used in workplace settings, difficulties in measuring cannabis-related workplace impairment, and a rapidly changing cultural ethos regarding cannabis. Although other articles have addressed many of the broad theoretical constructs, there exists little practical guidance on how workplace drug programs should address cannabis use by employees, both on the job and during off-hours. Materials and Methods: Research for this review was performed in the PubMed/National Library of Medicine database. Discussion: Cannabis use is associated with cognitive deficits, motivation problems, and perceptual distortions, so employers have a legitimate interest in preventing on-the-job impairment related to cannabis use. Similarly, employees have a legitimate interest in behaving as they wish outside of the workplace, as long as that behavior does not affect their job performance. Relevant statues and case law on the subject of cannabis in the workplace reflect different legal models across jurisdictions, in addition to legislators and judges' attempts to manage this tension between employer and employees. Conclusion: An effective workplace cannabis policy must fit into a larger workplace drug and alcohol policy. It should be constructed with a collaborative effort of addiction professionals, labor attorneys, and human resource professionals. Only then can the ultimate workplace cannabis policy comply with relevant laws, protect workplace safety and productivity, and support employees while remaining flexible enough to adapt to changes in the legal environment.

Chronic marijuana usage by human pancreas donors is associated with impaired islet function

We investigated the effect of chronic marijuana use, defined as 4 times weekly for more than 3 years, on human pancreatic islets. Pancreata from deceased donors who chronically used marijuana were compared to those from age, sex and ethnicity matched non-users. The islets from marijuana-users displayed reduced insulin secretion as compared to islets from non-users upon stimulation with high glucose (AUC, 3.41 ± 0.62 versus 5.14 ±0.47, p<0.05) and high glucose plus KCl (AUC, 4.48 ± 0.41 versus 7.69 ± 0.58, p<0.001). When human islets from chronic marijuana-users were transplanted into diabetic mice, the mean reversal rate of diabetes was 35% versus 77% in animals receiving islets from non-users (p<0.01). Immunofluorescent staining for cannabinoid receptor type 1 (CB1R) was shown to be colocalized with insulin and enhanced significantly in beta cells from marijuana-users vs. non-users (CB1R intensity/islet area, 14.95 ± 2.71 vs. 3.23 ± 0.87, p<0.001). In contrast, CB1R expression was not co-localized with glucagon or somatostatin. Furthermore, isolated islets from chronic marijuana-users appeared hypertrophic. In conclusion, excessive marijuana use affects islet endocrine phenotype and function in vitro and in vivo. Given the increasing use of marijuana, our results underline the importance of including lifestyle when evaluating human islets for transplantation or research.

Cannabinoids Drugs and Oral Health-From Recreational Side-Effects to Medicinal Purposes: A Systematic Review

Background: marijuana, the common name for cannabis sativa preparations, is one of the most consumed drug all over the world, both at therapeutical and recreational levels. With the legalization of medical uses of cannabis in many countries, and even its recreational use in most of these, the prevalence of marijuana use has markedly risen over the last decade. At the same time, there is also a higher prevalence in the health concerns related to cannabis use and abuse. Thus, it is mandatory for oral healthcare operators to know and deal with the consequences and effects of cannabis use on oral cavity health. This review will briefly summarize the components of cannabis and the endocannabinoid system, as well as the cellular and molecular mechanisms of biological cannabis action in human cells and biologic activities on tissues. We will also look into oropharyngeal tissue expression of cannabinoid receptors, together with a putative association of cannabis to several oral diseases. Therefore, this review will elaborate the basic biology and physiology of cannabinoids in human oral tissues with the aim of providing a better comprehension of the effects of its use and abuse on oral health, in order to include cannabinoid usage into dental patient health records as well as good medicinal practice. Methods: the paper selection was performed by PubMed/Medline and EMBASE electronic databases, and reported according to the PRISMA guidelines. The scientific products were included for qualitative analysis. Results: the paper search screened a total of 276 papers. After the initial screening and the eligibility assessment, a total of 32 articles were considered for the qualitative analysis. Conclusions: today, cannabis consumption has been correlated to a higher risk of gingival and periodontal disease, oral infection and cancer of the oral cavity, while the physico-chemical activity has not been completely clarified. Further investigations are necessary to evaluate a therapeutic efficacy of this class of drugs for the promising treatment of several different diseases of the salivary glands and oral diseases.

Cannabis roots: Pharmacological and toxicological studies in mice

ETHNOPHARMACOLOGICAL RELEVANCE

There are many studies and therapeutic properties attributed to the flowers and leaves of the Cannabis species, but even with few pharmacological studies, Cannabis sativa L. (Cannabaceae) roots presents several therapeutic indications in folk medicine.

AIM OF THE STUDY

This study aimed to evaluate the anti-inflammatory and spasmolytic effects as well as the toxicological profile of the aqueous extract of Cannabis sativa roots (CsAqEx) in mice.

MATERIALS AND METHODS

We assessed the anti-inflammatory effect with carrageenan-induced leukocyte migration assay, and carrageenan and histamine-induced paw edema methods; The spasmolytic effect was assessed through in vitro assays with isolated mice trachea. To assess motor coordination and mobility, mice went through the rotarod and open field tests, respectively. For the single-dose toxicity study, we administered CsAqEx at the dose of 1000 mg/kg by gavage. In a repeated dose toxicity study, animals received CsAqEx at doses of 25 mg or 100 mg/kg for 28 days.

RESULTS

The CsAqEx inhibited the migration of leukocytes at the doses of 25, 50, and 100 mg/kg. The CsAqEx showed anti-inflammatory activity after the intraplantar injection of carrageenan, presenting a reduction in edema formation at all tested doses (12.5, 25, 50 and 100 mg/kg). The dose of 12.5 mg/kg of CsAqEx prevented edema formation after intraplantar injection of histamine. In an organ bath, 729 μg/mL of CsAqEx did not promote spasmolytic effect on isolated mice tracheal rings contracted by carbachol (CCh) or potassium chloride (KCl). We did not observe clinical signs of toxicity in the animals after acute treatment with CsAqEx, which suggested that the median lethal dose (LD₅₀) is greater than 1000 mg/kg. Repeated dose exposure to the CsAqEx did not produce significant changes in hematological, biochemical, or organ histology parameters.

CONCLUSIONS

The results suggest that the anti-inflammatory effect of CsAqEx is related to the reduction of vascular extravasation and migration of inflammatory cells, without effects on the central nervous system. Moreover, there was no spasmolytic effect on airway smooth muscle and no toxicity was observed on mice.

Impaired motor cortical plasticity associated with cannabis use disorder in young adults

Maladaptive cortical plasticity has been described in individuals with heroin and methamphetamine addiction and may mediate other substance abuse disorders. It is unknown whether cannabis dependence in humans alters the capacity for induction of cortical plasticity. The aim of this study was to non-invasively investigate cortical plasticity with transcranial magnetic stimulation in young adults who meet DSM-5 criteria for cannabis use disorder (CUD). Thirty men (ages 20- 30) who used cannabis daily over the previous 6 months (15 diagnosed of CUD) and 15 demographically matched non-users were enrolled in this study. All participants underwent two sessions of theta burst stimulation (TBS) in which either continuous TBS (cTBS; 600 pulses, 80% active motor threshold) or intermittent TBS (iTBS; 2-s train of cTBS repeated every 10 s for a total of 190 s, 600 pulses) was applied over the primary motor cortex. The effects of these protocols were assessed by analysing the contralateral motor evoked potentials (MEPs). The relationships between cortical plasticity and problematic cannabis use, degree of dependence, and nicotine addiction were also investigated. Significant MEP inhibition after cTBS was observed in both cannabis users without CUD and non-users, while this inhibition was not seen in cannabis users with CUD. Strikingly, less motor cortical plasticity was observed in subjects with severe problematic cannabis use. No significant differences between users and non-users were found in the iTBS-induced cortical plasticity measures. Our study provides the first evidence of maladaptive cortical plasticity associated with cannabis use disorder and problematic cannabis use in humans.

Cannabis and driving ability

The aim of this review is to discuss recent evidence on cannabis and driving ability. In particular, the review examines experimental research on the acute effects of tetrahydrocannabinol (THC) on driving-related neurobehavioral skills and driving performance based on simulator and road course studies. The evidence indicates that certain driving abilities are significantly, albeit modestly, impaired in individuals experiencing the acute effects of THC. Treatment effects are moderated by dose, delivery method, recency of use, and tolerance development, with inconclusive evidence concerning the moderating influence of cannabidiol. Emerging research priorities include linking neurobehavioral deficits to specific decrements in driving performance, estimating the real-world implications of experimental impaired driving research, understanding how tolerance differentially affects driving impairment across subgroups, and developing more evidence on cannabidiol's potential role in mitigating THC-induced impairment.

Dopaminergic denervation impairs cortical motor and associative/limbic information processing through the basal ganglia and its modulation by the CB1 receptor

The basal ganglia (BG) are involved in cognitive/motivational functions in addition to movement control. Thus, BG segregated circuits, the sensorimotor (SM) and medial prefrontal (mPF) circuits, process different functional domains, such as motor and cognitive/motivational behaviours, respectively. With a high presence in the BG, the CB1 cannabinoid receptor modulates BG circuits. Furthermore, dopamine (DA), one of the principal neurotransmitters in the BG, also plays a key role in circuit functionality. Taking into account the interaction between DA and the endocannabinoid system at the BG level, we investigated the functioning of BG circuits and their modulation by the CB1 receptor under DA-depleted conditions. We performed single-unit extracellular recordings of substantia nigra pars reticulata (SNr) neurons with simultaneous cortical stimulation in sham and 6-hydroxydopamine (6-OHDA)-lesioned rats, together with immunohistochemical assays. We showed that DA loss alters cortico-nigral information processing in both circuits, with a predominant transmission through the hyperdirect pathway in the SM circuit and an increased transmission through the direct pathway in the mPF circuit. Moreover, although DA denervation does not change CB1 receptor density, it impairs its functionality, leading to a lack of modulation. These data highlight an abnormal transfer of information through the associative/limbic domains after DA denervation that may be related to the non-motor symptoms manifested by Parkinson's disease patients.

Thermographic detection and quantification of THC in oral fluid at unprecedented low concentrations

With recent changes in the legalization of cannabis around the world, there is an urgent need for rapid, yet sensitive, screening devices for testing drivers and employees under the influence of cannabis at the roadside and at the workplace, respectively. Oral fluid lateral flow immunoassays (LFAs) have recently been explored for such applications. While LFAs offer on-site, low-cost and rapid detection of tetrahydrocannabinol (THC), their nominal detection threshold is about 25 ng/ml, which is well above the 1-5 ng/ml per se limits set by regulations. In this paper, we report on the development of a thermo-photonic imaging system that utilizes the commercially available low-cost LFAs but offers detection of THC at unprecedented low concentrations. Our reader technology examines photothermal responses of gold nanoparticles (GNPs) in LFA through lock-in thermography (LIT). Our results (n = 300) suggest that the demodulation of localized surface plasmon resonance responses of GNPs captured by infrared cameras allows for detection of THC concentrations as low as 2 ng/ml with 96% accuracy. Quantification of THC concentration is also achievable with our technology through calibration.

Cannabis induced increase in striatal glutamate associated with loss of functional corticostriatal connectivity

Cannabis is the most commonly used illicit drug and is known to alter state of consciousness and impair neurocognitive function. However, the mechanisms underlying these effects have yet to be fully elucidated. Rodent studies suggest that Δ9-tetrahydrocannabinol (THC) activates dopaminergic neurons in the limbic system, subsequently enhancing dopamine, which is implicated in the rewarding effects of cannabis. Additional evidence suggests that THC may act indirectly on dopamine firing by modulating GABA and glutamate release. This double-blind, placebo-controlled study assessed the acute influence of two doses of THC on brain kinetics of glutamate, GABA, and dopamine, in relation to behavioral outcomes, by using magnetic resonance spectroscopy and functional magnetic resonance imaging. Twenty occasional cannabis users received acute doses of cannabis (300 µg/kg THC) and placebo, in one of two dose regimes (full dose and divided dose), during two separate testing days. Administration of THC increased striatal glutamate concentrations, and dopamine as indicated by a reduction in functional connectivity (FC) between the nucleus accumbens (NAc) and cortical areas. Alterations in glutamate and FC were dose dependent and evident in the full dose group where THC serum concentrations exceeded 2 ng/ml at T-max. Average glutamate changes correlated strongly with FC alterations. Additionally, THC induced changes in FC correlated with feelings of subjective high and decreased performance on an attention task. Taken together, this suggests that THC elicits subjective and cognitive alterations via increased striatal dopaminergic activity and loss of corticostriatal connectivity, which is associated with an increase in striatal glutamate.

Cannabis involvement and neuropsychological performance: findings from the Human Connectome Project

BACKGROUND

There is evidence that heavy cannabis use is associated with decrements in cognitive performance, but findings are mixed and studies are often limited by small sample sizes and narrow adjustment for potential confounding variables. In a comparatively large sample, the current study examined associations between multiple indicators of cannabis use in relation to performance on a variety of neuropsychological tasks.

METHODS

Participants were 1121 adults (54% female) enrolled in the Human Connectome Project. Cannabis involvement comprised recent cannabis use (positive tetrahydrocannabinol screen), total number of lifetime uses, cannabis use disorder and age at first use. The neuropsychological battery comprised performance in episodic memory, fluid intelligence, attention, working memory, executive function, impulsive decision-making, processing speed and psychomotor dexterity. Covariates were age, sex, income, family structure and alcohol and tobacco use.

RESULTS

Positive urinary tetrahydrocannabinol status was associated with worse performance in episodic memory and processing speed, and positive cannabis use disorder status was associated with lower fluid intelligence (all p < 0.005). No other significant associations were present.

LIMITATIONS

The sample was limited to young adults aged 22–36 years. The measures of cannabis involvement were relatively coarse.

CONCLUSION

Beyond an array of potential confounders, recent cannabis use was associated with deficits in memory and psychomotor performance, and cannabis use disorder was associated with lower overall cognitive functioning in a large normative sample of adults. The findings pertaining to recent use have particular relevance for occupational settings.

Druggable targets of the endocannabinoid system: Implications for the treatment of HIV-associated neurocognitive disorder

HIV-associated neurocognitive disorder (HAND) affects nearly half of all HIV-infected individuals. Synaptodendritic damage correlates with neurocognitive decline in HAND, and many studies have demonstrated that HIV-induced neuronal injury results from excitotoxic and inflammatory mechanisms. The endocannabinoid (eCB) system provides on-demand protection against excitotoxicity and neuroinflammation. Here, we discuss evidence of the neuroprotective and anti-inflammatory properties of the eCB system from in vitro and in vivo studies. We examine the pharmacology of the eCB system and evaluate the therapeutic potential of drugs that modulate eCB signaling to treat HAND. Finally, we provide perspective on the need for additional studies to clarify the role of the eCB system in HIV neurotoxicity and speculate that strategies that enhance eCB signaling might slow cognitive decline in HAND.

Motor Adaptation Impairment in Chronic Cannabis Users Assessed by a Visuomotor Rotation Task

Background—The cerebellum has been recently suggested as an important player in the addiction brain circuit. Cannabis is one of the most used drugs worldwide, and its long-term effects on the central nervous system are not fully understood. No valid clinical evaluations of cannabis impact on the brain are available today. The cerebellum is expected to be one of the brain structures that are highly affected by prolonged exposure to cannabis, due to its high density in endocannabinoid receptors. We aim to use a motor adaptation paradigm to indirectly assess cerebellar function in chronic cannabis users (CCUs). Methods—We used a visuomotor rotation (VMR) task that probes a putatively-cerebellar implicit motor adaptation process together with the learning and execution of an explicit aiming rule. We conducted a case-control study, recruiting 18 CCUs and 18 age-matched healthy controls. Our main measure was the angular aiming error. Results—Our results show that CCUs have impaired implicit motor adaptation, as they showed a smaller rate of adaptation compared with healthy controls (drift rate: 19.3 +/− 6.8° vs. 27.4 +/− 11.6°; t(26) = −2.1, p = 0.048, Cohen’s d = −0.8, 95% CI = (−1.7, −0.15)). Conclusions—We suggest that a visuomotor rotation task might be the first step towards developing a useful tool for the detection of alterations in implicit learning among cannabis users.

Cannabinoids differentially modulate cortical information transmission through the sensorimotor or medial prefrontal basal ganglia circuits

BACKGROUND AND PURPOSE

In the sensorimotor (SM) and medial prefrontal (mPF) basal ganglia (BG) circuits, the cortical information is transferred to the substantia nigra pars reticulata (SNr) through the hyperdirect trans-subthalamic pathway and through the direct and indirect trans-striatal pathways. The cannabinoid CB₁ receptor, which is highly expressed in both BG circuits, may participate in the regulation of motor and motivational behaviours. Here, we investigated the modulation of cortico-nigral information transmission through the BG circuits by cannabinoids.

EXPERIMENTAL APPROACH

We used single-unit recordings of SNr neurons along with simultaneous electrical stimulation of motor or mPF cortex in anaesthetized rats.

KEY RESULTS

Cortical stimulation elicited a triphasic response in the SNr neurons from both SM and mPF-BG circuits, which consisted of an early excitation (hyperdirect transmission pathway), an inhibition (direct transmission pathway), and a late excitation (indirect transmission pathway). In the SM circuit, after Δ⁹ -tetrahydrocannabinol or WIN 55,212-2 administration, the inhibition and the late excitation were decreased or completely lost, whereas the early excitation response remained unaltered. However, cannabinoid administration dramatically decreased all the responses in the mPF circuit. The CB₁ receptor antagonist AM251 (2 mg·kg^-1 , i.v.) did not modify the triphasic response, but blocked the effects induced by cannabinoid agonists.

CONCLUSIONS AND IMPLICATIONS

CB₁ receptor activation modulates the SM information transmission through the trans-striatal pathways and profoundly decreases the cortico-BG transmission through the mPF circuit. These results may be relevant for elucidating the involvement of the cannabinoid system in motor performance and in decision making or goal-directed behaviour.

Cannabis users exhibit increased cortical activation during resting state compared to non-users

Studies have shown altered task-based brain functioning as a result of cannabis use. To date, however, whether similar alterations in baseline resting state and functional organization of neural activity are observable in cannabis users remains unknown. We characterized global resting state cortical activations and functional connectivity via electroencephalography (EEG) in cannabis users and related these activations to measures of cannabis use. Resting state EEG in the eyes closed condition was collected from age- and sex-matched cannabis users (N = 17; 6 females; mean age = 30.9 ± 7.4 years) and non-using controls (N = 21; 9 females; mean age = 33.1 ± 11.6 years). Power spectral density and spectral coherence were computed to determine differences in cortical activations and connectivity between the two groups in the delta (1-4Hz), theta (4-7 Hz), alpha (8-12 Hz), beta (13-30 Hz), and gamma (31-50 Hz) frequency bands. Cannabis users exhibited decreased delta and increased theta, beta, and gamma power compared to controls, suggesting increased cortical activation in resting state and a disinhibition of inhibitory functions that may interrupt cognitive processes. Cannabis users also exhibited increased interhemispheric and intrahemispheric coherence relative to controls, reduced mean network degree, and increased clustering coefficient in specific regions and frequencies. This increased cortical activity may indicate a loss of neural refinement and efficiency that may indicate a "noisy" brain. Lastly, measures related to cannabis use were correlated with spectral power and functional connectivity measures, indicating that specific electrophysiological signals are associated with cannabis use. These results suggest that there are differences in cortical activity and connectivity between cannabis users and non-using controls in the resting state that may be related to putative cognitive impairments and can inform effectiveness of intervention programs.

Addiction vulnerability trait impacts complex movement control: Evidence from sign-trackers

Cognitive-motivational vulnerability traits are associated with increased risk for substance addiction and relapse. Sign-tracking (ST) behavior in rats is associated with poor attentional control, mediated by an unresponsive basal forebrain cholinergic system, and an increased risk for substance addiction/relapse. A separate literature links poor attentional control and cholinergic losses to increased fall risk in Parkinson's disease. Here we tested the hypothesis that the relatively inferior attentional control of STs extends to complex movement control and a propensity for falls. STs were found to fall more often than goal-trackers (GTs) while traversing a straight rotating rod and, similar to human fallers, when taxed by a secondary task. Furthermore, STs fell more often while traversing a rotating zig-zag rod. GTs exhibited fewer falls from this rod by avoiding entry to the rotating zig-zag sections when in, or rotating toward, a difficult traversal state. Goal-tracking rats approached risky movement situations using strategies indicative of superior top-down control. These results suggest that the impact of opponent cognitive-cholinergic traits extends to complex movement control, and that impairments in the cognitive-motor interface are likely to be comorbid with addiction vulnerability. Sign-tracking indexes an endophenotype that may increase the risk for a wide range of neurobehavioral disorders.

Meta-analysis of neurocognition in young psychosis patients with current cannabis use

OBJECTIVE

Adult psychosis patients (i.e. over the age of 25 years) who are also lifetime cannabis users (CANN±) appear to exhibit superior cognition compared to never-using patients (CANN-). The objective of this meta-analysis was to evaluate the cognitive differences between CANN- and patients who currently use cannabis (CANN+) (i.e. during the CANN± patients' cannabis-using stage). Specifically, focusing on young patients under the age of 25 years, the typical stage of both psychosis- and cannabis-onset.

METHOD

Of the 308 studies identified through database searches and secondary referencing, 14 compared neurocognition of CANN+ and CANN- in young people with psychotic disorders (mean age between 15 and 45 years). Effect sizes were extracted using neurocognitive test performance between CANN+ and CANN- and random effects modelling was conducted on pooled ES and moderator analyses.

RESULTS

CANN+ performed worse on several cognitive domains (i.e. premorbid IQ, current IQ, verbal learning, verbal working memory, motor inhibition) compared to CANN-. The association between age and performance in CANN+ cognition was varied, with older age predictive of worse performance in processing speed, sustained attention, verbal memory, and better performance in verbal learning and very fluency. Of note, CANN+ outperformed CANN- in tests of conceptual set-shifting.

CONCLUSION

These results are consistent with previous findings indicating that CANN+ demonstrate poorer neurocognition than CANN-; and that this is exacerbated with increasing age. Our findings demonstrate significant cognitive differences between patients with CANN+ versus CANN- even at early-onset psychosis, which could suggest a different underlying mechanism towards psychosis for cannabis users.

Neurosteroid Levels in Patients With Bipolar Disorder and a History of Cannabis Use Disorders

PURPOSE/BACKGROUND

In animal models, levels of the neurosteroid pregnenolone increase after tetrahydrocannabinol (THC) administration and pregnenolone appears to attenuate the brain effects of THC. Given these interactions between pregnenolone and THC, we evaluated baseline neurosteroid levels in participants with a history of a cannabis use disorders (CUDs).

METHODS/PROCEDURES

Bipolar depressed participants were enrolled in a randomized placebo-controlled clinical trial to evaluate the efficacy of add-on pregnenolone for depression and before receiving pregnenolone or placebo. Baseline serum levels of neurosteroids (pregnenolone, allopregnanolone, pregnanolone, and androsterone) were analyzed in 53 participants with highly sensitive and specific gas chromatography/mass spectrometry. Current, active substance use disorders, or a positive baseline urine drug screen, were exclusionary. Participants were classified by past cannabis abuse or dependence diagnosis using the structured clinical interview for Diagnostic and Statistical Manual of Mental Disorders, Fourth Edition. Data were analyzed by independent t tests for separate neurosteroids.

FINDINGS/RESULTS

Participants with a history of CUD had higher serum pregnanolone, lower allopregnanolone, a higher pregnanolone to allopregnanolone ratio, and a lower pregnenolone to pregnanolone ratio compared with those without a history of cannabis use. Similar findings were not observed based on a history of other substance use disorders with the exception of lower allopregnanolone in those with opioid use disorders. Notably, the majority of those with an opioid use disorder also had a CUD (75%).

IMPLICATIONS/CONCLUSIONS

These findings potentially suggest either enduring changes in neurosteroids in people with past CUDs or represent a vulnerability marker for a CUD.

Impact of Regular Cannabis Use on Biomarkers of Lower Urinary Tract Function

OBJECTIVE

To evaluate the differences in the composition and quantities of urine peptides in regular cannabis users and nonusers by liquid chromatography tandem mass spectrometry analysis.

MATERIALS AND METHODS

Urine specimens from healthy control subjects and cannabis users were utilized to identify the differences in the number and quantity of urine proteins by liquid chromatography tandem mass spectrometry analysis. Significantly altered proteins were determined by a permutation testing statistical method. Heat map, dendrogram, pathway, and network analyses were performed to assess the degree of expression and the potential relationships between proteins in both groups.

RESULTS

A total of 1337 proteins were detected in both groups with 19 proteins being significantly altered in cannabis users. Innate immunity and carbohydrate metabolic pathways were highly linked with upregulated proteins in the cannabis group. Additionally, 91 proteins were present and 46 proteins were absent only in cannabis users in comparison with the control cohort. Our results suggest that regular use of cannabis is associated with significant alterations in a number of urinary peptides, with a large number of proteins present or absent only in cannabis users. Pathway analyses demonstrated an increased immune response in cannabis users compared with controls.

CONCLUSION

Our observations potentially indicate activation (or inhibition) of specific signaling pathways in the lower urinary tract during chronic exposure to exogenous cannabinoids. Our study provides initial proteomic knowledge for future investigations on the potential role of exocannabinoids in the development of intravesical therapies to treat lower urinary tract disorders.

Drug candidates in clinical trials for Alzheimer's disease

Alzheimer's disease (AD) is a major form of senile dementia, characterized by progressive memory and neuronal loss combined with cognitive impairment. AD is the most common neurodegenerative disease worldwide, affecting one-fifth of those aged over 85 years. Recent therapeutic approaches have been strongly influenced by five neuropathological hallmarks of AD: acetylcholine deficiency, glutamate excitotoxicity, extracellular deposition of amyloid-β (Aβ plague), formation of intraneuronal neurofibrillary tangles (NTFs), and neuroinflammation. The lowered concentrations of acetylcholine (ACh) in AD result in a progressive and significant loss of cognitive and behavioral function. Current AD medications, memantine and acetylcholinesterase inhibitors (AChEIs) alleviate some of these symptoms by enhancing cholinergic signaling, but they are not curative. Since 2003, no new drugs have been approved for the treatment of AD. This article focuses on the current research in clinical trials targeting the neuropathological findings of AD including acetylcholine response, glutamate transmission, Aβ clearance, tau protein deposits, and neuroinflammation. These investigations include acetylcholinesterase inhibitors, agonists and antagonists of neurotransmitter receptors, β-secretase (BACE) or γ-secretase inhibitors, vaccines or antibodies targeting Aβ clearance or tau protein, as well as anti-inflammation compounds. Ongoing Phase III clinical trials via passive immunotherapy against Aβ peptides (crenezumab, gantenerumab, and aducanumab) seem to be promising. Using small molecules blocking 5-HT6 serotonin receptor (intepirdine), inhibiting BACE activity (E2609, AZD3293, and verubecestat), or reducing tau aggregation (TRx0237) are also currently in Phase III clinical trials. We here systemically review the findings from recent clinical trials to provide a comprehensive review of novel therapeutic compounds in the treatment and prevention of AD.

Cross-Cultural Effects of Cannabis Use Disorder: Evidence to Support a Cultural Neuroscience Approach

PURPOSE OF REVIEW

Cannabis use disorders (CUDs) are prevalent worldwide. Current epidemiological studies underscore differences in behaviors that contribute to cannabis use across cultures that can be leveraged towards prevention and treatment of CUDs. This review proposes a framework for understanding the effects of cross-cultural differences on psychological, neural, and genomic processes underlying CUDs that has the potential to inform global policies and impact global public health.

RECENT FINDINGS

We found that cultural factors may influence (1) the willingness to acknowledge CUD-related symptoms among populations of different countries, and (2) neural responses related to the sense of self, perception, emotion, and attention. These findings leverage the potential effects of culture on neural mechanisms underlying CUDs.

SUMMARY

As the number of individuals seeking treatment for CUDs increases globally, it is imperative to incorporate cultural considerations to better understand and serve differing populations and develop more targeted treatment strategies and interventions.

The effect of task difficulty on motor performance and frontal-striatal connectivity in cocaine users

BACKGROUND

There is growing recognition that chronic cocaine users have alterations in sensorimotor control that are positively related to low frontal-striatal connectivity within the motor system. These frontal-striatal motor circuits however, are modulated by circuits governing attention, which are also disrupted in cocaine users. This study's aim was to determine if sensorimotor control deficits are positively related to the difficulty of a motor task or exist independent of the increasing cognitive demand.

METHODS

Functional MRI data was collected from 40 individuals (20 non-treatment seeking chronic cocaine users, 20 age and gender matched non-drug using controls) as they mimicked an unpredictable finger-tapping sequence at various speeds. Dependent measures included task accuracy, percent BOLD signal change in sensorimotor regions of interest (ROIs), and functional connectivity (temporal correlations) between ROIs.

RESULTS

In both groups, as speed increased, the BOLD signal change increased in the primary motor cortex, supplementary motor area (SMA), cerebellum, and anterior cingulate cortex. Compared to controls, cocaine user SMA-Caudate and ACC-Putamen connectivity was lower at all speeds in the contralateral hemisphere. Furthermore, as speed increased there was a decrease in connectivity between additional ROI pairs among users.

CONCLUSIONS

These data support previous observations of sensorimotor performance deficits and dorsal frontal-striatal connectivity impairments among cocaine users. While previous studies demonstrate these deficits when performing a finger-tapping task at a single speed, we show that these same impairments exist at multiple levels of task difficulty. These data suggest that previously observed frontal-striatal connectivity in cocaine users during sensorimotor task performance are stable and not directly related to cognitive demands of the task.