Cannabis and the brain

Cannabinoid Hyperemesis

Cannabinoid hyperemesis syndrome (CHS) is a paradoxical condition in which a long-term cannabis user suffers an episode of intractable vomiting that may last days separated by longer asymptomatic periods of weeks or months. Cannabinoids are often utilized for their antiemetic properties, so CHS can be a puzzling condition, and the diagnosis of CHS may be disputed by patients. Unlike other cyclic vomiting syndromes, CHS can be relieved by hot showers or topical capsaicin. Abstinence from cannabinoids causes CHS to resolve, sometimes in a matter of days or hours. Marijuana users as well as many clinicians are not aware of CHS, and patients may undergo unnecessary tests, scans, and other procedures to get an accurate diagnosis. Symptoms may be severe enough to require hospitalization. With liberalization of marijuana laws and favorable public opinion about the healing properties of cannabis, CHS may be more frequently observed in clinical practice.

Subregional Hippocampal Thickness Abnormalities in Older Adults with a History of Heavy Cannabis Use

Background and Aims: Legalization of cannabis (CB) for both medicinal and, in some states, recreational use, has given rise to increasing usage rates across the country. Of particular concern are indications that frequent CB use may be selectively harmful to the developing adolescent brain compared with adult-onset usage. However, the long-term effects of heavy, adolescent CB use on brain structure and cognitive performance in late-life remain unknown. A critical brain region is the hippocampus (HC), where there is a striking intersection between high concentrations of cannabinoid 1 (CB1) receptors and age-related pathology.

Design: We investigated whether older adults (average age=66.6+7.2 years old) with a history of early life CB use show morphological differences in hippocampal subregions compared with older, nonusers.

Methods: We performed high-resolution magnetic resonance imaging combined with computational techniques to assess cortical thickness of the medial temporal lobe, neuropsychological testing, and extensive drug use histories on 50 subjects (24 formerly heavy cannabis users [CB+ group] abstinent for an average of 28.7 years, 26 nonusers [CB− group]). We investigated group differences in hippocampal subregions, controlling for age, sex, and intelligence (as measured by the Wechsler Test of Adult Reading), years of education, and cigarette use.

Results: The CB+ subjects exhibited thinner cortices in subfields cornu ammonis 1 [CA1; F(1,42)=9.96, p=0.0003], and CA2, 3, and the dentate gyrus [CA23DG; F(1,42)=23.17, p<0.0001], and in the entire HC averaged over all subregions [F(1,42)=8.49, p=0.006].

Conclusions: Negative effects of chronic adolescent CB use on hippocampal structure are maintained well into late life. Because hippocampal cortical loss underlies and exacerbates age-related cognitive decline, these findings have profound implications for aging adults with a history of early life usage.

Clinical Trial Registration: ClinicalTrials.gov # NCT01874886.

Marijuana Use and Depressive Symptoms; Gender Differences in African American Adolescents

Introduction: This study aimed to examine gender differences in the bidirectional associations between marijuana use and depressive symptoms among African American adolescents. The study also tested gender differences in the effects of socioeconomic status, maternal support, and friends' drug use on adolescents' depressive symptoms and marijuana use. Methods: This is a secondary analysis of the Flint Adolescent Study (FAS). Six hundred and eighty one African American adolescents (335 males and 346 females) were followed for 3 years, from 1995 (mean age 16) to 1997 (mean age 19). Depressive symptoms (Brief Symptom Inventory) and marijuana use were measured annually during the follow up. We used multi-group latent growth curve modeling to explore the reciprocal associations between depressive symptoms and marijuana use over time based on gender. Results: Baseline marijuana use was predictive of an increase in depressive symptoms over time among male but not female African American adolescents. Baseline depressive symptoms were not predictive of an increase in marijuana use among male or female adolescents. Conclusion: Study findings suggest that male African American adolescents who use marijuana are at an increased risk of subsequent depressive symptoms. Interventions that combine screening and treatment for marijuana use and depression may be indicated for African American male adolescents.

Regular cannabis use is associated with altered activation of central executive and default mode networks even after prolonged abstinence in adolescent users: Results from a complementary meta-analysis

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Adolescent abstinent cannabis users showed significantly greater activation in the dorsolateral and ventrolateral prefrontal and posterior parietal cortices compared to controls.

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Adolescent users showed increased activation in regions involved in executive functioning, attentional control and the default mode network compared to non-using controls.

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No significant group differences in brain activation observed between abstinent and current adolescent cannabis users.

Whether the effects of cannabis use on brain function persist or recover following abstinence remains unclear. Therefore, using meta-analytic techniques, we examined whether functional alterations measured using fMRI persist in cannabis users abstinent for over 25 days (or 600 h) as evidence suggests that the effects on cognitive performance no longer persist beyond this period. Systematic literature search identified 20 studies, of which, 12 examined current cannabis users (CCU) (361 CCU versus 394 non-cannabis using controls (NU)) and 3 examined abstinent cannabis users (ACU) in 5 separate comparisons (98 ACU versus 106 NU). Studies in ACU were carried out in adolescents and suggest significantly greater activation in components of the central executive and default mode networks in adolescent ACU compared to NU. While this evidence is to be interpreted with caution because studies were carried out in overlapping samples, they indicate a pressing need for independent confirmation whether certain neurofunctional alterations in adolescent cannabis users may persist even after cannabis and its metabolites are likely to have left their bodies.

Increased use of illicit drugs in a Dutch cluster headache population

Introduction

Many patients with cluster headache report use of illicit drugs. We systematically assessed the use of illicit drugs and their effects in a well-defined Dutch cluster headache population.

Methods

In this cross-sectional explorative study, 756 people with cluster headache received a questionnaire on lifetime use and perceived effects of illicit drugs. Results were compared with age and sex-matched official data from the Dutch general population.

Results

Compared to the data from the general population, there were more illicit drug users in the cluster headache group (31.7% vs. 23.8%; p < 0.01). Reduction in attack frequency was reported by 56% (n = 22) of psilocybin mushroom, 60% (n = 3) of lysergic acid diethylamide and 50% (n = 2) of heroin users, and a decreased attack duration was reported by 46% (n = 18) of PSI, 50% (n = 2) of heroin and 36% (n = 8) of amphetamine users.

Conclusion

In the Netherlands, people with cluster headache use illicit drugs more often than the general population. The question remains whether this is due to an actual alleviatory effect, placebo response, conviction, or common pathophysiological background between cluster headache and addictive behaviours such as drug use.

Potential Clinical Benefits of CBD-Rich Cannabis Extracts Over Purified CBD in Treatment-Resistant Epilepsy: Observational Data Meta-analysis

This meta-analysis paper describes the analysis of observational clinical studies on the treatment of refractory epilepsy with cannabidiol (CBD)-based products. Beyond attempting to establish the safety and efficacy of such products, we also investigated if there is enough evidence to assume any difference in efficacy between CBD-rich extracts compared to purified CBD products. The systematic search took place in February/2017 and updated in December/2017 using the keywords "epilepsy" or "Dravet" or "Lennox-Gastaut" or "CDKL5" combined with "Cannabis," "cannabinoid," "cannabidiol," or "CBD" resulting in 199 papers. The qualitative assessment resulted in 11 valid references, with an average impact factor of 8.1 (ranging from 1.4 to 47.8). The categorical data of a total of 670 patients were analyzed by Fischer test. The average daily dose ranged between 1 and 50 mg/kg, with treatment length from 3 to 12 months (mean 6.2 months). Two thirds of patients reported improvement in the frequency of seizures (399/622, 64%). There were more reports of improvement from patients treated with CBD-rich extracts (318/447, 71%) than patients treated with purified CBD (81/175, 46%), [corrected] with statistical significance (p < 0.0001). Nevertheless, when the standard clinical threshold of a "50% reduction or more in the frequency of seizures" was applied, only 39% of the individuals were considered "responders," and there was no difference (p = 0.52) [corrected] between treatments with CBD-rich extracts (122/330, 37%) [corrected] and purified CBD (94/223, 42%). Patients treated with CBD-rich extracts reported lower average dose (6.0 mg/kg/day) [DOSAGE ERROR CORRECTED] than those using purified CBD (25.3 mg/kg/day). [DOSAGE ERROR CORRECTED] The reports of mild (158/216 76% vs. 148/447, 33% p < 0.001) and severe (41/155, 26% vs. 23/328, 7% p < 0.0001) [corrected] adverse effects were more frequent in products containing purified CBD than in CBD-rich extracts. CBD-rich extracts seem to present a better therapeutic profile than purified CBD, at least in this population of patients with refractory epilepsy. The roots of this difference is likely due to synergistic effects of CBD with other phytocompounds (aka Entourage effect), but this remains to be confirmed in controlled clinical studies.

Cardiovascular Complications of Marijuana and Related Substances: A Review

The recreational use of cannabis has sharply increased in recent years in parallel with its legalization and decriminalization in several countries. Commonly, the traditional cannabis has been replaced by potent synthetic cannabinoids and cannabimimetics in various forms. Despite overwhelming public perception of the safety of these substances, an increasing number of serious cardiovascular adverse events have been reported in temporal relation to recreational cannabis use. These have included sudden cardiac death, vascular (coronary, cerebral and peripheral) events, arrhythmias and stress cardiomyopathy among others. Many of the victims of these events are relatively young men with few if any cardiovascular risk factors. However, there are reasons to believe that older individuals and those with risk factors for or established cardiovascular disease are at even higher danger of such events following exposure to cannabis. The pathophysiological basis of these events is not fully understood and likely encompasses a complex interaction between the active ingredients (particularly the major cannabinoid, Δ9-tetrahydrocannabinol), and the endo-cannabinoid system, autonomic nervous system, as well as other receptor and non-receptor mediated pathways. Other complicating factors include opposing physiologic effects of other cannabinoids (predominantly cannabidiol), presence of regulatory proteins that act as metabolizing enzymes, binding molecules, or ligands, as well as functional polymorphisms of target receptors. Tolerance to the effects of cannabis may also develop on repeated exposures at least in part due to receptor downregulation or desensitization. Moreover, effects of cannabis may be enhanced or altered by concomitant use of other illicit drugs or medications used for treatment of established cardiovascular diseases. Regardless of these considerations, it is expected that the current cannabis epidemic would add significantly to the universal burden of cardiovascular diseases.

Patterns of medicinal cannabis use, strain analysis, and substitution effect among patients with migraine, headache, arthritis, and chronic pain in a medicinal cannabis cohort

BACKGROUND

Medicinal cannabis registries typically report pain as the most common reason for use. It would be clinically useful to identify patterns of cannabis treatment in migraine and headache, as compared to arthritis and chronic pain, and to analyze preferred cannabis strains, biochemical profiles, and prescription medication substitutions with cannabis.

METHODS

Via electronic survey in medicinal cannabis patients with headache, arthritis, and chronic pain, demographics and patterns of cannabis use including methods, frequency, quantity, preferred strains, cannabinoid and terpene profiles, and prescription substitutions were recorded. Cannabis use for migraine among headache patients was assessed via the ID Migraine™ questionnaire, a validated screen used to predict the probability of migraine.

RESULTS

Of 2032 patients, 21 illnesses were treated with cannabis. Pain syndromes accounted for 42.4% (n = 861) overall; chronic pain 29.4% (n = 598;), arthritis 9.3% (n = 188), and headache 3.7% (n = 75;). Across all 21 illnesses, headache was a symptom treated with cannabis in 24.9% (n = 505). These patients were given the ID Migraine™ questionnaire, with 68% (n = 343) giving 3 "Yes" responses, 20% (n = 102) giving 2 "Yes" responses (97% and 93% probability of migraine, respectively). Therefore, 88% (n = 445) of headache patients were treating probable migraine with cannabis. Hybrid strains were most preferred across all pain subtypes, with "OG Shark" the most preferred strain in the ID Migraine™ and headache groups. Many pain patients substituted prescription medications with cannabis (41.2-59.5%), most commonly opiates/opioids (40.5-72.8%). Prescription substitution in headache patients included opiates/opioids (43.4%), anti-depressant/anti-anxiety (39%), NSAIDs (21%), triptans (8.1%), anti-convulsants (7.7%), muscle relaxers (7%), ergots (0.4%).

CONCLUSIONS

Chronic pain was the most common reason for cannabis use, consistent with most registries. The majority of headache patients treating with cannabis were positive for migraine. Hybrid strains were preferred in ID Migraine™, headache, and most pain groups, with "OG Shark", a high THC (Δ9-tetrahydrocannabinol)/THCA (tetrahydrocannabinolic acid), low CBD (cannabidiol)/CBDA (cannabidiolic acid), strain with predominant terpenes β-caryophyllene and β-myrcene, most preferred in the headache and ID Migraine™ groups. This could reflect the potent analgesic, anti-inflammatory, and anti-emetic properties of THC, with anti-inflammatory and analgesic properties of β-caryophyllene and β-myrcene. Opiates/opioids were most commonly substituted with cannabis. Prospective studies are needed, but results may provide early insight into optimizing crossbred cannabis strains, synergistic biochemical profiles, dosing, and patterns of use in the treatment of headache, migraine, and chronic pain syndromes.

Biphasic effects of THC in memory and cognition

A generally undesired effect of cannabis smoking is a reversible disruption of short-term memory induced by delta-9-tetrahydrocannabinol (THC), the primary psychoactive component of cannabis. However, this paradigm has been recently challenged by a group of scientists who have shown that THC is also able to improve neurological function in old animals when chronically administered at low concentrations. Moreover, recent studies demonstrated that THC paradoxically promotes hippocampal neurogenesis, prevents neurodegenerative processes occurring in animal models of Alzheimer's disease, protects from inflammation-induced cognitive damage and restores memory and cognitive function in old mice. With the aim to reconcile these seemingly contradictory facts, this work will show that such paradox can be explained within the framework of hormesis, defined as a biphasic dose-response.

Pharmacotherapeutic considerations for use of cannabinoids to relieve pain in patients with malignant diseases

Purpose

The aim of this review was to assess the efficacy of cannabis preparations for relieving pain in patients with malignant diseases, through a systematic review of randomized controlled trials (RCTs), which were predominantly double-blind trials that compared cannabis preparation to a placebo.

Methods

An electronic search of all literature published until June 2017 was made in MEDLINE/PubMed, Embase, The Cochrane Controlled Trials Register and specific web pages devoted to cannabis.

Results

Fifteen of the 18 trials demonstrated a significant analgesic effect of cannabinoids as compared to placebo. The most commonly reported adverse effects were generally well tolerated, mild to moderate. The main side effects were drowsiness, nausea, vomiting and dry mouth. There is evidence that cannabinoids are safe and modestly effective in neuropathic pain and also for relieving pain in patients with malignant diseases. The proportion of “responders” (patients who at the end of 2 weeks of treatment reported ≥30% reduction in pain intensity on a scale of 0–10, which is considered to be clinically important) was 43% in comparison with placebo (21%).

Conclusion

The target dose for relieving pain in patients with malignant diseases is most likely about 10 actuations per day, which is about 27 mg tetrahydrocannabinol (THC) and 25 mg cannabidiol (CBD), and the highest approved recommended dose is 12 actuations per day (32 mg THC/30 mg CBD). Further large studies of cannabinoids in homogeneous populations are required.

A review of medical marijuana for the treatment of posttraumatic stress disorder: Real symptom re-leaf or just high hopes?

Introduction:

The incidence of posttraumatic stress disorder (PTSD) is common within the population and even more so among veterans. Current medication treatment is limited primarily to antidepressants. Such medicines have shown to produce low remission rates and may require 9 patients to be treated for 1 to have a response. Aside from the Veterans Affairs/Department of Defense guidelines, other guidelines do not recommend pharmacotherapy as a first-line option, particularly in the veteran population. Marijuana has been evaluated as an alternative and novel treatment option with 16 states legalizing its use for PTSD.

Methods:

A systematic search was conducted to evaluate the evidence for the use of marijuana for PTSD. Studies for the review were included based on a literature search from Ovid MEDLINE and Google Scholar.

Results:

Five studies were identified that evaluated the use of marijuana for PTSD. One trial was conducted in Israel and actively used marijuana. Three studies did not use marijuana in the treatment arm but instead evaluated the effects postuse. A retrospective chart review from New Mexico relied on patients to recall their change in PTSD symptoms when using marijuana. Three studies concluded there might be a benefit, but two discouraged its use. Although the two negative studies show a statistical difference in worse PTSD outcomes, clinical significance is unclear.

Discussion:

Conflicting data exist for the use of marijuana for PTSD; however, current evidence is limited to anecdotal experiences, case reports, and observational studies, making it difficult to make clinical recommendations.

Cannabinoid Receptors and the Endocannabinoid System: Signaling and Function in the Central Nervous System

The biological effects of cannabinoids, the major constituents of the ancient medicinal plant Cannabis sativa (marijuana) are mediated by two members of the G-protein coupled receptor family, cannabinoid receptors 1 (CB1R) and 2. The CB1R is the prominent subtype in the central nervous system (CNS) and has drawn great attention as a potential therapeutic avenue in several pathological conditions, including neuropsychological disorders and neurodegenerative diseases. Furthermore, cannabinoids also modulate signal transduction pathways and exert profound effects at peripheral sites. Although cannabinoids have therapeutic potential, their psychoactive effects have largely limited their use in clinical practice. In this review, we briefly summarized our knowledge of cannabinoids and the endocannabinoid system, focusing on the CB1R and the CNS, with emphasis on recent breakthroughs in the field. We aim to define several potential roles of cannabinoid receptors in the modulation of signaling pathways and in association with several pathophysiological conditions. We believe that the therapeutic significance of cannabinoids is masked by the adverse effects and here alternative strategies are discussed to take therapeutic advantage of cannabinoids.

Residual effects of cannabis use in adolescent and adult brains - A meta-analysis of fMRI studies

While numerous studies have investigated the residual effects of cannabis use on human brain function, results of these studies have been inconsistent. Using meta-analytic approaches we summarize the effects of prolonged cannabis exposure on human brain function as measured using task-based functional MRI (fMRI) across studies employing a range of cognitive activation tasks comparing regular cannabis users with non-users. Separate meta-analyses were carried out for studies investigating adult and adolescent cannabis users. Systematic literature search identified 20 manuscripts (13 adult and 7 adolescent studies) meeting study inclusion criteria. Adult analyses compared 530 cannabis users to 580 healthy controls while adolescent analyses compared 219 cannabis users to 224 healthy controls. In adult cannabis users brain activation was increased in the superior and posterior transverse temporal and inferior frontal gyri and decreased in the striate area, insula and middle temporal gyrus. In adolescent cannabis users, activation was increased in the inferior parietal gyrus and putamen compared to healthy controls. Functional alteration in these areas may reflect compensatory neuroadaptive changes in cannabis users.

Cannabinoid hyperemesis syndrome: Review of the literature and of cases reported to the French addictovigilance network

BACKGROUND

Cannabinoid hyperemesis syndrome is a variant of cyclical vomiting syndrome in a context of chronic cannabis usage. Our aim was to compare French cases to those identified in the international literature in order to further our knowledge of the clinical criteria, pathophysiology and treatments for cannabinoid hyperemesis syndrome.

METHODS

We analysed cases reported in the international literature up to 30 June 2017, obtained from the MEDLINE, PsycINFO and The Cochrane Library databases; we selected relevant articles based on title and abstract. We also analysed cases of cannabinoid hyperemesis syndrome reported to the French addictovigilance network.

RESULTS

A systematic search through the three databases enabled us to identify 137 articles. Finally, 55 articles were selected as they involved reported cases. In total, 113 cases were reported in these 55 articles. We were thus able to analyse 29 reported French cases of cannabinoid hyperemesis syndrome. Cannabinoid hyperemesis syndrome mainly affects young male subjects who have been smoking cannabis daily for several years. Taking hot baths or showers is the most effective means of relieving the symptoms, while antiemetics and dopamine antagonists do not appear to effective for relieving nausea and vomiting.

CONCLUSIONS

French cases display the same characteristics as the cases identified in the international literature. The pathophysiology of cannabinoid hyperemesis syndrome is unclear and several hypotheses have been put forward in the literature. We have only begun to characterise the syndrome, though there is an outbreak of cannabinoid hyperemesis syndrome in France.

Cyclic vomiting syndrome: a case series and review of the literature

OBJECTIVE

Cyclic vomiting syndrome (CVS) is under-recognised. Treatment is difficult as the pathophysiology is incompletely understood. We report our experience of treating patients with amitriptyline, and review the literature to summarise symptoms and associated features, epidemiology, potential pathophysiological mechanisms, differential diagnoses and treatment.

DESIGN

Consecutive adult patients with CVS were identified during a 5-year period from January 2010 until December 2015. Medical records were reviewed retrospectively, and age and sex of the patient, symptoms, associated features and response to treatment with amitriptyline were recorded.

SETTING

A luminal gastroenterology clinic at a teaching hospital.

RESULTS

Seventeen patients were identified (mean age 29.8 years, 13 (76.5%) female). Five had a history of cannabis use. Duration of symptoms prior to diagnosis ranged from 5 months to 15 years. Fourteen patients commenced amitriptyline, and in eight (57.1%) symptoms either ceased entirely or improved. Review of the literature suggested the prevalence of CVS was 0.5%. Symptoms are stereotypical, with acute episodes of nausea and vomiting, interspersed by periods when the patient is symptom-free. Proposed pathophysiologies include neuroendocrine dysfunction, mutations in mitochondrial DNA and re-intoxication effects from cannabis stored in fat tissues. Treatment during the acute phase is supportive, with rehydration, sedation and antiemetics. Prophylaxis to prevent future attacks with antihistamines, antimigraine drugs, antiepileptics and tricyclic antidepressants may be beneficial. Complete cessation of cannabis smoking should be advised.

CONCLUSIONS

Diagnosis of CVS is often delayed in adults. Once identified, patients respond well to amitriptyline.

Cannabis Intoxication Case Series: The Dangers of Edibles Containing Tetrahydrocannabinol

STUDY OBJECTIVE

Cannabis and its principal active constituent, Δ9-tetrahydrocannabinol (THC), are increasingly available as edibles resembling commercially available food products. In this case series, we describe a population of predominantly pediatric patients who were inadvertently exposed to a THC-containing product in San Francisco.

METHODS

Twelve children and 9 adults were identified, with 16 patients having detectable serum THC and THC metabolites. All patients presented to hospitals with a variety of constitutional symptoms and all were discharged home within 12 hours.

RESULTS

In general, pediatric patients had more severe symptoms and longer hospital length of stay, and, uniquely, a majority presented with leukocytosis and elevated lactic acid levels.

CONCLUSION

We recommend that efforts be made to increase general public awareness in regard to the potential hazards of THC-containing edibles resembling commercially available food products.

Effect of WIN55-212-2 and Consequences of Extinction Training on Conditioned Fear Memory in PTSD Male Rats

Introduction

This study investigates the effects of cannabinoid agonist WIN55-212-2 on acquisition and consolidation phases of the fear memory extinction and also on anxiety and motor activity.

Methods

In this study, we used SPS & S model to induce post-traumatic stress disorder. One week after SPS, to establish a conditioned fear memory, rats received an electric foot shock within shock chamber. After 24 h, for extinction training, the rats were placed back to the chamber for 9 min, without receiving any shock. In 3 consecutive days and on days 17, 24 and 37, extinction tests were carried out and the freezing behavior was evaluated. Thirty minutes before the first three extinction tests, animals received IP injections of WIN or vehicle. Anxiety-like behavior examined with elevated plus-maze and motor activity with open field, 32 days after conditioning.

Results

Exaggerated and continued conditioned fear memory observed in SPS & S group compared with shock group. IP injection of a 0.25 mg/kg dose of WIN before extinction training led to reducing fear responses in animals.

Conclusion

IP injection of WIN increased acquisition or consolidation of fear memory extinction. SPS & S caused anxiety and this effect improved by the agonist (0.25 mg/kg).

A preliminary study of endocannabinoid system regulation in psychosis: Distinct alterations of CNR1 promoter DNA methylation in patients with schizophrenia

Compelling evidence supports the involvement of the endocannabinoid system (ECS) in psychosis vulnerability. We here evaluated the transcriptional regulation of ECS components in human peripheral blood mononuclear cells (PBMCs) obtained from subjects suffering from bipolar disorder, major depressive disorder and schizophrenia, focusing in particular on the effects of DNA methylation. We observed selective alterations of DNA methylation at the promoter of CNR1, the gene coding for the type-1 cannabinoid receptor, in schizophrenic patients (N=25) with no changes in any other disorder. We confirmed the regulation of CNR1 in a well-validated animal model of schizophrenia, induced by prenatal methylazoxymethanol (MAM) acetate exposure (N=7 per group) where we found, in the prefrontal cortex, a significant increase in CNR1 expression and a consistent reduction in DNA methylation at specific CpG sites of gene promoter. Overall, our findings suggest a selective dysregulation of ECS in psychosis, and highlight the evaluation of CNR1 DNA methylation levels in PBMCs as a potential biomarker for schizophrenia.

Cannabis Withdrawal: A Review of Neurobiological Mechanisms and Sex Differences

PURPOSE OF REVIEW

This report provides an updated overview of pre-clinical and clinical research on the etiology and biological substrates of the cannabis withdrawal syndrome.

RECENT FINDINGS

Long-term cannabis use is associated with downregulation of type-1 cannabinoid receptors (CB1). Reduced CB1 receptor density is related to increased withdrawal during early abstinence, and the reduction in CB1 receptor density reverses with extended abstinence. Females have been shown to have increased rate and severity of a subset of cannabis withdrawal symptoms compared with men.

SUMMARY

Recent studies have extended knowledge of the biological processes and individual difference variables that influence cannabis withdrawal. However, caveats include small sample sizes in clinical studies, participant samples that are predominantly male, and limited examinations of endocannabinoids, enzymes that degrade endocannabinoids, negative allosteric modulators, and other neurobiological systems that may directly impact cannabis withdrawal symptom expression.

Endo-cannabinoids system and the toxicity of cannabinoids with a biotechnological approach

Cannabinoids have shown diverse and critical effects on the body systems, which alter the physiological functions. Synthetic cannabinoids are comparatively innovative misuse drugs with respect to their nature of synthesis. Synthetic cannabinoids therapy in healthy, chain smokers, and alcoholic individuals cause damage to the immune and nervous system, eventually leading to intoxication throughout the body. Relevant studies were retrieved using major electronic databases such as PubMed, EMBASE, Medline, Scopus, and Google Scholar. The extensive use of Cannabis Sativa L. (C. Sativa) and its derivatives/analogues such as the nonpsychoactive dimethyl heptyl homolog (CBG-DMH), and tetrahydrocannabivarin (THCV) amongst juveniles and adults have been enhanced in recent years. Cannabinoids play a crucial role in the induction of respiratory, reproductive, immune and carcinogenic effects; however, potential data about mutagenic and developmental effects are still insufficient. The possible toxicity associated with the prolong use of cannabinoids acts as a tumor promoter in animal models and humans. Particular synthetic cannabinoids and analogues have low affinity for CB1 or CB2 receptors, while some synthetic members like Δ9-THC have high affinity towards these receptors. Cannabinoids and their derivatives have a direct or indirect association with acute and long-term toxicity. To reduce/attenuate cannabinoids toxicity, pharmaceutical biotechnology and cloning methods have opened a new window to develop cannabinoids encoding the gene tetrahydrocannabinolic acid (THCA) synthase. Plant revolution and regeneration hindered genetic engineering in C. Sativa. The genetic culture suspension of C. Sativa can be transmuted by the use of Agrobacterium tumefaciens to overcome its toxicity. The main aim of the present review was to collect evidence of the endo-cannabinoid system (ECS), cannabinoids toxicity, and the potential biotechnological approach of cannabinoids synthesis.

Caffeine and Cannabis Effects on Vital Neurotransmitters and Enzymes in the Brain Tissue of Juvenile Experimental Rats

BACKGROUND

Caffeine and cannabis are globally consumed and abused psychoactive substances. While caffeine is legally used in various forms, including in tea and coffee as beverages, it is also consumed in soda and energy drinks as additives. Cannabis, on the other hand, is considered illegal in most countries; albeit, it is being consumed globally particularly by adolescents.

PURPOSE

The adolescent stage marks a critical stage of brain development and maturation. Influences of agents on the brain at this stage may affect neuronal structural and functional attributes. To this end, the current experiment considered the effects of cannabis and caffeine on selected key neurotransmitters and enzymes in the brain tissues after regimented caffeine and cannabis treatment for 21 days.

METHODS

A total of 72 juvenile Wistar rats that were approximately 40 days old were divided into 6 groups A-F. The group A served as the control. Other groups were administered various dosages of caffeine or cannabis in distilled water, using oral gavages as follows: group B animals received 100 mg/kg body weight of caffeine, group C animals received 50 mg/kg body weight of caffeine, group D animals received 500 mg/kg body weight of cannabis, group E animals received 200 mg/kg body weight of cannabis, and group F received a low dose of cannabis (200 mg/kg body weight) plus a low dose of caffeine (50 mg/kg body weight). The animals were killed by cervical dislocation 24 h after the last administration. The brain tissues were excised and homogenized. The enzymes cytochrome C oxidase and glucose-6-phosphate dehydrogenase were assayed to observe tissue energy metabolism while the neurotransmitters gamma-amino butyric acid (GABA), glutamate, and dopamine were assayed to observe the effects of the psychoactive substances on their activities relative to mental activities.

RESULTS

GABA, glutamate, and dopamine were generally higher in the treated groups of animals. The levels of G-6-PDH were higher in all treated animals' brains. Caffeine produced quite more significant effects relative to cannabis and the combination of both increased the level of G-6-PDH significantly.

CONCLUSION

Results showed that caffeine and cannabis influenced the activities of the enzymes and neurotransmitters in the brain. Both stimulants altered brain chemistry relative to the tested enzymes and neurotransmitters.

Effects on Spasticity and Neuropathic Pain of an Oral Formulation of Δ9-tetrahydrocannabinol in Patients WithProgressive Multiple Sclerosis

PURPOSE

The aim of the present study was to evaluate the efficacy of an oral formulation of Δ9-tetrahydrocannabinol (ECP002A) in patients with progressive multiple sclerosis (MS).

METHODS

This accelerated proof-of-concept study consisted of 2 phases: a crossover challenge (dose-finding) phase and a 4-week, parallel, randomized, placebo-controlled treatment phase. Twenty-four patients with progressive MS and moderate spasticity were enrolled. During the treatment phase, biomarkers for efficacy and secondary pharmacodynamic effects were measured at baseline and after 2 and 4 weeks of treatment. Serum samples were collected to determine pharmacokinetic properties and perform population modeling. Safety and tolerability profiles were assessed based on adverse events and safety measurements.

FINDINGS

Pain was significantly reduced when measured directly after administration of ECP002A in the clinic but not when measured in a daily diary. A similar pattern was observed in subjective muscle spasticity. Other clinical outcomes were not significantly different between active treatment and placebo. Cognitive testing indicated that there was no decline in cognition after 2 or 4 weeks of treatment attributable to ECP002A compared with placebo. Implications This study specifically underlines the added value of thorough investigation of pharmacokinetic and pharmacodynamic associations in the target population. Despite the complex interplay of psychoactive effects and analgesia, the current oral formulation of Δ9-tetrahydrocannabinol may play a role in the treatment of spasticity and pain associated with MS because it was well tolerated and had a stable pharmacokinetic profile.

Cannabinoids in Parkinson's Disease

The endocannabinoid system plays a regulatory role in a number of physiological processes and has been found altered in different pathological conditions, including movement disorders. The interactions between cannabinoids and dopamine in the basal ganglia are remarkably complex and involve both the modulation of other neurotransmitters (γ-aminobutyric acid, glutamate, opioids, peptides) and the activation of different receptors subtypes (cannabinoid receptor type 1 and 2). In the last years, experimental studies contributed to enrich this scenario reporting interactions between cannabinoids and other receptor systems (transient receptor potential vanilloid type 1 cation channel, adenosine receptors, 5-hydroxytryptamine receptors). The improved knowledge, adding new interpretation on the biochemical interaction between cannabinoids and other signaling pathways, may contribute to develop new pharmacological strategies. A number of preclinical studies in different experimental Parkinson's disease (PD) models demonstrated that modulating the cannabinoid system may be useful to treat some motor symptoms. Despite new cannabinoid-based medicines have been proposed for motor and nonmotor symptoms of PD, so far, results from clinical studies are controversial and inconclusive. Further clinical studies involving larger samples of patients, appropriate molecular targets, and specific clinical outcome measures are needed to clarify the effectiveness of cannabinoid-based therapies.

Neurotoxicology and drug-related disorders

Neuropsychiatric disorders caused by toxic substances pose a great diagnostic challenge due to the large variety of changes caused in the central and peripheral nervous system. The pathogenetic mechanisms at work are multifaceted and partly not solved. In human drug abusers (cannabis, opiates, cocaine, amphetamines, methamphetamine and "designer drugs"), a broad spectrum of central nervous system alterations are observed including infarction, intracerebral and subarachnoidal hemorrhage, hypoxic-ischemic leukoencephalopathy, infections, neuronal loss, specific astroglial and microglial reaction patterns, and vascular changes, including the endothelial cell as well as the basal lamina.

Expression of Cannabinoid Type 1 Receptors in Human Odontoblast Cells

INTRODUCTION

The aim of this study was to investigate the functional expression of cannabinoid type 1 (CB1) receptors in human odontoblasts (HODs) and the possible internal mechanism.

METHODS

In the present study, we examined the molecular and functional expression of the CB1 receptors in cultured HOD-like cells and native HODs obtained from healthy wisdom teeth.

RESULTS

Immunohistochemistry and immunofluorescence revealed that CB1 receptors localize to native HODs and HOD-like cells, respectively. Both reverse-transcription polymerase chain reaction and Western blot analysis confirmed gene and protein expression of CB1 receptors. The ultrastructural distribution by immunoelectron microscopy also found that CB1 receptors labeled by colloidal gold particles distribute sparsely in the cytoplasm and odontoblastic processes. In functional assays, 2-arachidonyl glycerol, as an agonist of CB receptors, elicited the increase of intracellular fluorescence intensity that could be inhibited by a CB1-specific receptor antagonist rather than a selective CB2 receptor antagonist with fluo-3AM Ca²⁺ fluorescence. The source of the increase of intracellular fluorescence intensity elicited by CB1 receptors was from extracellular Ca²⁺ but not intracellular Ca²⁺ stores. The process of 2-arachidonyl glycerol activating CB1 receptors modulated transient receptor potential vanilloid 1-mediated Ca²⁺ entry via the cyclic adenosine monophosphate signaling pathway.

CONCLUSIONS

We conclude that HODs can express functional CB1 receptors that may play an important role in mediating the physiological function in tooth pulp.

Relationship Between Frequent Recreational Cannabis (Marijuana and Hashish) Use and Periodontitis in Adults in the United States: National Health and Nutrition Examination Survey 2011 to 2012

BACKGROUND

Recreational use of cannabis, following its legalization in some countries, poses emergent oral and periodontal health concerns. The objective of this study is to examine the relationship between frequent recreational cannabis (FRC) (marijuana and hashish) use and periodontitis prevalence among adults in the United States.

METHODS

Data from the National Health and Nutrition Examination Survey (NHANES) 2011 to 2012 were analyzed. Primary outcome (periodontitis) was defined using the Centers for Disease Control and Prevention/American Academy of Periodontology classification as well as continuous measurements of probing depth (PD) and clinical attachment loss (AL). Exposure of interest was self-reported cannabis use, defined as "FRC use" versus "non-FRC use." Bivariate and multivariable regression models were performed using the entire analytical sample (model 1) as well as those who had never used tobacco (never-users) (model 2).

RESULTS

Of 1,938 participants with available cannabis use data and essential covariates, 26.8% were FRC users. Mean number of sites per participant with PD ≥4, ≥6, and ≥8 mm and AL ≥3, ≥5, and ≥8 mm was significantly higher among FRC users than among non-FRC users (mean difference in number of PD sites: 6.9, 5.6, and 5.6; P <0.05; mean difference in number of AL sites: 12.7, 7.6, and 5.6; P <0.05). Average AL was higher among FRC users than among non-FRC users (1.8 versus 1.6 mm; P = 0.004). Bivariate analysis revealed positive (harmful) association between FRC use and severe periodontitis in the entire sample (odds ratio [OR]: 1.7, 95% confidence interval [CI]: 1.3 to 2.4; P = 0.002) as well as in never-smokers (OR: 2.0, 95% CI: 1.2 to 3.5; P = 0.01). This association was retained in multivariable models adjusted for demographics (age, sex, race/ethnicity, and income level), alcohol and tobacco use, diabetes mellitus, and past periodontal treatment (model 1: adjusted OR [aOR]: 1.4, 95% CI: 1.1 to 1.9; P = 0.07; model 2: aOR: 1.9, 95% CI: 1.1 to 3.2; P = 0.03).

CONCLUSION

FRC use is associated with deeper PDs, more clinical AL, and higher odds of having severe periodontitis.

Synthetic Cannabis Overdose and Withdrawal in a Young Adult: A Case Report, Commentary on Regulation, and Review of the Literature

Introduction. Marijuana has been used for its psychotropic effects including enhanced relaxation and perceptual alterations. However, the use of synthetic marijuana (SM) leads to more frequent and drastic side effects than the typical use of regular marijuana, owing to the fact that SM has a shorter duration and an earlier peak of action. Despite all the potential adverse health effects associated with SM use, current health policies on SM are very limited. It is believed that the popularity of SM has increased, due to its easy accessibility in the US and lack of detection in typical urine drug screens for THC. Case Report. One case presented is of a young adult patient, with histories of recurrent synthetic cannabis and recreational cannabis use, who had developed drastic physiological and psychiatric symptoms, including the development of acute-onset psychosis. Conclusion/Discussion. This case, as many others nationwide, exemplifies the impact of synthetic cannabinoid use and abuse in adolescents. Side effects and adverse health consequences of synthetic cannabinoid use warrant stricter regulations and policies in order to decrease psychiatric hospital admissions and associated healthcare costs.

Medical Marijuana and Chronic Pain: a Review of Basic Science and Clinical Evidence

Cannabinoid compounds include phytocannabinoids, endocannabinoids, and synthetics. The two primary phytocannabinoids are delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD), with CB1 receptors in the brain and peripheral tissue and CB2 receptors in the immune and hematopoietic systems. The route of delivery of cannabis is important as the bioavailability and metabolism are very different for smoking versus oral/sublingual routes. Gold standard clinical trials are limited; however, some studies have thus far shown evidence to support the use of cannabinoids for some cancer, neuropathic, spasticity, acute pain, and chronic pain conditions.

Dorsal hippocampal NMDA receptors mediate the interactive effects of arachidonylcyclopropylamide and MDMA/ecstasy on memory retrieval in rats

A combination of cannabis and ecstasy may change the cognitive functions more than either drug alone. The present study was designed to investigate the possible involvement of dorsal hippocampal NMDA receptors in the interactive effects of arachidonylcyclopropylamide (ACPA) and ecstasy/MDMA on memory retrieval. Adult male Wistar rats were cannulated into the CA1 regions of the dorsal hippocampus (intra-CA1) and memory retrieval was examined using the step-through type of passive avoidance task. Intra-CA1 microinjection of a selective CB1 receptor agonist, ACPA (0.5-4ng/rat) immediately before the testing phase (pre-test), but not after the training phase (post-training), impaired memory retrieval. In addition, pre-test intra-CA1 microinjection of MDMA (0.5-1μg/rat) dose-dependently decreased step-through latency, indicating an amnesic effect of the drug by itself. Interestingly, pre-test microinjection of a higher dose of MDMA into the CA1 regions significantly improved ACPA-induced memory impairment. Moreover, pre-test intra-CA1 microinjection of a selective NMDA receptor antagonist, D-AP5 (1 and 2μg/rat) inhibited the reversal effect of MDMA on the impairment of memory retrieval induced by ACPA. Pre-test intra-CA1 microinjection of the same doses of D-AP5 had no effect on memory retrieval alone. These findings suggest that ACPA or MDMA consumption can induce memory retrieval impairment, while their co-administration improves this amnesic effect through interacting with hippocampal glutamatergic-NMDA receptor mechanism. Thus, it seems that the tendency to abuse cannabis with ecstasy may be for avoiding cognitive dysfunction.

Cannabis use and cognitive function in first episode psychosis: differential effect of heavy use

RATIONALE

First episode patients and patients with schizophrenia exhibit increased rates of cannabis use compared to the general population. Contrary to what has been reported in studies with healthy people, most of the published studies so far have reported no impairments or even beneficial effects on neurocognition associated with cannabis consumption in psychotic patients. However, these studies did not address the effects of very high cannabis consumption.

OBJECTIVES

Our aim in this study was to assess the effects on neurocognition of medium and heavy cannabis consumption in first psychotic episode patients.

METHODS

A total of 74 patients were included in the study and assigned to three different groups according to their mean cannabis consumption during the last year (non-users, medium users, and heavy users). Participants were administered verbal memory and other neurocognitive tasks.

RESULTS

Heavy cannabis users were significantly impaired in all the verbal memory measures with respect to non-users, including immediate (p = .026), short-term (p = .005), and long-term (p = .002) memory. There were no significant differences between medium and non-users. Moreover, non-users performed better than all cannabis users in the arithmetic task (p = .020). Heavy cannabis consumption was associated with more commission errors in the continuous performance task (CPT) (p = .008) and more time to complete trail making test A (TMT-A) (p = .008), compared to the group of medium users.

CONCLUSIONS

Heavy cannabis consumption seems to impair verbal memory in first psychotic episode patients. Heavy users also perform worse than medium users in other neurocognitive tasks. Based on the results and the available evidence, a dose-related effect of cannabis consumption is suggested.

Structural imaging for addiction medicine: From neurostructure to neuroplasticity

Quantitative morphometry and diffusion tensor imaging have provided new insights into structural brain changes associated with drugs of abuse. In this chapter, we review recent studies using these methods to investigate structural brain abnormalities associated with excessive use of marijuana, stimulants, and opiates. Although many brain regions have been associated with structural abnormalities following abuse of these drugs, brain systems underlying inhibition, mood regulation, and reward are particularly involved. Candidate pathological mechanisms underlying these structural abnormalities include the direct toxic effects of the drugs, neuroinflammation, ischemia, hemorrhage, and abnormal brain development. Returning damaged brain areas to neural health would involve enhancing neuroplasticity. Behavioral, environmental, pharmacological, and cell-based therapies have been correlated with enhanced neuroplasticity following brain injury, providing a basis for new treatments of brain changes associated with excessive drug use. When testing new treatments, structural imaging may prove useful in selecting patients, monitoring recovery, and perhaps, tailoring interventions.

The effects of cannabis on memory function in users with and without a psychotic disorder: findings from a combined meta-analysis

BACKGROUND

Effect of cannabis use on memory function is a contentious issue, with effects being different in healthy individuals and patients with psychosis.

METHOD

Employing a meta-analytic approach we investigated the effects of cannabis use on memory function in patients with psychosis and healthy individuals, and the effect of diagnosis, memory dimension and moderating factors. A total of 88 studies were identified through a systematic literature search, investigating healthy (n = 7697) and psychotic (n = 3261) individuals. Standardized mean differences between the cannabis user and non-user groups on memory tasks were estimated using random-effects models and the effect-size statistic Cohen's d. Effects of potential moderating factors were tested using mixed-effects models and subgroup analyses.

RESULTS

We found that cannabis use was associated with significantly (p ⩽ 0.05) impaired global (d = 0.27) and prospective memory (d = 0.61), verbal immediate (d = 0.40) and delayed (d = 0.36) recall as well as visual recognition (d = 0.41) in healthy individuals, but a better global memory (d = -0.11), visual immediate recall (d = -0.73) and recognition (d = -0.42) in patients. Lower depression scores and younger age appeared to attenuate the effects of cannabis on memory. Cannabis-using patients had lower levels of depression and were younger compared with non-using patients, whilst healthy cannabis-users had higher depression scores than age-matched non-users. Longer duration of abstinence from cannabis reduced the effects on memory in healthy and patient users.

CONCLUSIONS

These results suggest that cannabis use is associated with a significant domain-specific impairment in memory in healthy individuals but not in cannabis-using patients, suggesting that they may represent a less developmentally impaired subgroup of psychotic patients.

Cortical thickness in adolescent marijuana and alcohol users: A three-year prospective study from adolescence to young adulthood

Studies suggest marijuana impacts gray and white matter neural tissue development, however few prospective studies have determined the relationship between cortical thickness and cannabis use spanning adolescence to young adulthood. This study aimed to understand how heavy marijuana use influences cortical thickness trajectories across adolescence. Subjects were adolescents with heavy marijuana use and concomitant alcohol use (MJ+ALC, n=30) and controls (CON, n=38) with limited substance use histories. Participants underwent magnetic resonance imaging and comprehensive substance use assessment at three independent time points. Repeated measures analysis of covariance was used to look at main effects of group, time, and Group × Time interactions on cortical thickness. MJ+ALC showed thicker cortical estimates across the brain (23 regions), particularly in frontal and parietal lobes (ps<.05). More cumulative marijuana use was associated with increased thickness estimates by 3-year follow-up (ps<.05). Heavy marijuana use during adolescence and into young adulthood may be associated with altered neural tissue development and interference with neuromaturation that can have neurobehavioral consequences. Continued follow-up of adolescent marijuana users will help understand ongoing neural changes that are associated with development of problematic use into adulthood, as well as potential for neural recovery with cessation of use.