Category Archives: Schizophrenia

Phytocannabinoids modulate emotional memory processing through interactions with the ventral hippocampus and mesolimbic dopamine system: implications for neuropsychiatric pathology.

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Psychopharmacology

“Growing clinical and preclinical evidence suggests a potential role for the phytocannabinoid cannabidiol (CBD) as a pharmacotherapy for various neuropsychiatric disorders. In contrast, delta-9-tetrahydrocannabinol (THC), the primary psychoactive component in cannabis, is associated with acute and neurodevelopmental propsychotic side effects through its interaction with central cannabinoidtype 1 receptors (CB1Rs). CB1R stimulation in the ventral hippocampus (VHipp) potentiates affective memory formation through inputs to the mesolimbic dopamine (DA) system, thereby altering emotional salience attribution. These changes in DA activity and salience attribution, evoked by dysfunctional VHipp regulatory actions and THC exposure, could predispose susceptible individuals to psychotic symptoms. Although THC can accelerate the onset of schizophrenia, CBD displays antipsychotic properties, can prevent the acquisition of emotionally irrelevant memories, and reverses amphetamine-induced neuronal sensitization through selective phosphorylation of the mechanistic target of rapamycin (mTOR) molecular signaling pathway. This review summarizes clinical and preclinical evidence demonstrating that distinct phytocannabinoids act within the VHipp and associated corticolimbic structures to modulate emotional memory processing through changes in mesolimbic DA activity states, salience attribution, and signal transduction pathways associated with schizophrenia-related pathology.”

 https://www.ncbi.nlm.nih.gov/pubmed/29063964
https://link.springer.com/article/10.1007%2Fs00213-017-4766-7

An Update on Safety and Side Effects of Cannabidiol: A Review of Clinical Data and Relevant Animal Studies.

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Mary Ann Liebert, Inc. publishers

“This literature survey aims to extend the comprehensive survey performed by Bergamaschi et al. in 2011 on cannabidiol (CBD) safety and side effects. Apart from updating the literature, this article focuses on clinical studies and CBD potential interactions with other drugs.

Results: In general, the often described favorable safety profile of CBD in humans was confirmed and extended by the reviewed research. The majority of studies were performed for treatment of epilepsy and psychotic disorders. Here, the most commonly reported side effects were tiredness, diarrhea, and changes of appetite/weight. In comparison with other drugs, used for the treatment of these medical conditions, CBD has a better side effect profile. This could improve patients’ compliance and adherence to treatment. CBD is often used as adjunct therapy. Therefore, more clinical research is warranted on CBD action on hepatic enzymes, drug transporters, and interactions with other drugs and to see if this mainly leads to positive or negative effects, for example, reducing the needed clobazam doses in epilepsy and therefore clobazam’s side effects.

Conclusion: This review also illustrates that some important toxicological parameters are yet to be studied, for example, if CBD has an effect on hormones. Additionally, more clinical trials with a greater number of participants and longer chronic CBD administration are still lacking.”

 https://www.ncbi.nlm.nih.gov/pubmed/28861514
http://online.liebertpub.com/doi/10.1089/can.2016.0034

Even High Doses of Oral Cannabidol Do Not Cause THC-Like Effects in Humans

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Mary Ann Liebert, Inc. publishers

“Cannabidiol (CBD) is a cannabinoid of the cannabis plant devoid of intoxicating effects. It may be of therapeutic value in a large number of diseases, including epilepsy, anxiety disorders, depression, schizophrenic psychosis, inflammatory diseases, dystonia, nausea, and vomiting without causing relevant or severe side effects.

No biosynthetic enzyme or pathway exists in the human body to convert CBD to THC.

This short communication examines the question whether the experimental data presented in a study by Merrick et al. are of clinical relevance. These authors found that cannabidiol (CBD), a major cannabinoid of the cannabis plant devoid of psychotropic effects and of great interest for therapeutic use in several medical conditions, may be converted in gastric fluid into the psychoactive cannabinoids delta-8-THC and delta-9-THC to a relevant degree. They concluded that “the acidic environment during normal gastrointestinal transit can expose orally CBD-treated patients to levels of THC and other psychoactive cannabinoids that may exceed the threshold for a positive physiological response.” They issued a warning concerning oral use of CBD and recommend the development of other delivery methods.

However, the available clinical data do not support this conclusion and recommendation, since even high doses of oral CBD do not cause psychological, psychomotor, cognitive, or physical effects that are characteristic for THC or cannabis rich in THC. On the contrary, in the past decades and by several groups, high doses of oral CBD were consistently shown to cause opposite effects to those of THC in clinical studies. In addition, administration of CBD did not result in detectable THC blood concentrations.

Thus, there is no reason to avoid oral use of CBD, which has been demonstrated to be a safe means of administration of CBD, even at very high doses.”

https://www.ncbi.nlm.nih.gov/pubmed/28861499

http://online.liebertpub.com/doi/full/10.1089/can.2016.0036

“A Conversion of Oral Cannabidiol to Delta9-Tetrahydrocannabinol Seems Not to Occur in Humans.”  https://www.ncbi.nlm.nih.gov/pubmed/28861507

Modulation of Astrocyte Activity by Cannabidiol, a Nonpsychoactive Cannabinoid.

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“The astrocytes have gained in recent decades an enormous interest as a potential target for neurotherapies, due to their essential and pleiotropic roles in brain physiology and pathology. Their precise regulation is still far from understood, although several candidate molecules/systems arise as promising targets for astrocyte-mediated neuroregulation and/or neuroprotection.

The cannabinoid system and its ligands have been shown to interact and affect activities of astrocytes. Cannabidiol (CBD) is the main non-psychotomimetic cannabinoid derived from Cannabis. CBD is devoid of direct CB1 and CB2 receptor activity, but exerts a number of important effects in the brain. Here, we attempt to sum up the current findings on the effects of CBD on astrocyte activity, and in this way on central nervous system (CNS) functions, across various tested models and neuropathologies.

The collected data shows that increased astrocyte activity is suppressed in the presence of CBD in models of ischemia, Alzheimer-like and Multiple-Sclerosis-like neurodegenerations, sciatic nerve injury, epilepsy, and schizophrenia. Moreover, CBD has been shown to decrease proinflammatory functions and signaling in astrocytes.”

https://www.ncbi.nlm.nih.gov/pubmed/28788104

http://www.mdpi.com/1422-0067/18/8/1669

Compared to high and low cannabis use, moderate use is associated with fewer cognitive deficits in psychosis.

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Schizophrenia Research: Cognition

“Literature on the relationship of cannabis use and cognition in schizophrenia provides the paradoxical view that cannabis use is sometimes linked with less severe impairment in neurocognition.

This paper explored the possibility that this is a reflection of a dose related response between lifetime cannabis use and two forms of cognition, neurocognition and metacognition, in schizophrenia. It was hypothesized that three groups of patients could be differentiated, those with (1) little to no cannabis use with poor levels of cognition, (2) moderate cannabis use and relatively better levels of cognition and (3) high cannabis use with relatively poorer levels of cognition.

Consistent with our hypothesis, participants with high and moderate lifetime cannabis use had lesser impairment of neurocognition and metacognition compared to low lifetime cannabis use. Participants with moderate lifetime cannabis use also had lesser impairment of metacognition compared to low and heavy use.

These findings suggest that a dose related relationship exists between cannabis use and cognition. Results could be due to an influence of pre-existing cognitive level on likelihood of lifetime cannabis use, or to an interaction between use and cognitive function.”

https://www.ncbi.nlm.nih.gov/pubmed/28740820

http://www.sciencedirect.com/science/article/pii/S2215001316300166?via%3Dihub

An Overview on Medicinal Chemistry of Synthetic and Natural Derivatives of Cannabidiol.

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“Cannabidiol (CBD) has been traditionally used in Cannabis-based preparation, however historically, it has received far less interest as a single drug than the other components of Cannabis. Currently, CBD generates considerable interest due to its beneficial neuroprotective, antiepileptic, anxiolytic, antipsychotic, and anti-inflammatory properties. Therefore, the CBD scaffold becomes of increasing interest for medicinal chemists. This review provides an overview of the chemical structure of natural and synthetic CBD derivatives including the molecular targets associated with these compounds. A clear identification of their biological targets has been shown to be still very challenging.”  https://www.ncbi.nlm.nih.gov/pubmed/28701957

http://journal.frontiersin.org/article/10.3389/fphar.2017.00422/full

Plastic and Neuroprotective Mechanisms Involved in the Therapeutic Effects of Cannabidiol in Psychiatric Disorders.

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“Beneficial effects of cannabidiol (CBD) have been described for a wide range of psychiatric disorders, including anxiety, psychosis, and depression. The mechanisms responsible for these effects, however, are still poorly understood. Similar to clinical antidepressant or atypical antipsychotic drugs, recent findings clearly indicate that CBD, either acutely or repeatedly administered, induces plastic changes. For example, CBD attenuates the decrease in hippocampal neurogenesis and dendrite spines density induced by chronic stress and prevents microglia activation and the decrease in the number of parvalbumin-positive GABA neurons in a pharmacological model of schizophrenia. More recently, it was found that CBD modulates cell fate regulatory pathways such as autophagy and others critical pathways for neuronal survival in neurodegenerative experimental models, suggesting the potential benefit of CBD treatment for psychiatric/cognitive symptoms associated with neurodegeneration. These changes and their possible association with CBD beneficial effects in psychiatric disorders are reviewed here.”

https://www.ncbi.nlm.nih.gov/pubmed/28588483

http://journal.frontiersin.org/article/10.3389/fphar.2017.00269/full

Medicinal Uses of Marijuana and Cannabinoids

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“In the past two decades, there has been increasing interest in the therapeutic potential of cannabis and single cannabinoids, mainly cannabidiol (CBD) and delta-9-tetrahydrocannabinol (THC). THC and cannabis products rich in THC exert their effects mainly through the activation of cannabinoid receptors (CB1 and CB2). Since 1975, 140 controlled clinical trials using different cannabinoids or whole-plant preparations for the treatment of a large number of disorders and symptoms have been conducted. Results have led to the approval of cannabis-based medicines [dronabinol, nabilone, and the cannabis extract nabiximols (Sativex®, THC:CBD = 1:1)] as well as cannabis flowers in several countries. Controlled clinical studies provide substantial evidence for the use of cannabinoid receptor agonists in cancer chemotherapy induced nausea and vomiting, appetite loss and cachexia in cancer and HIV patients, neuropathic and chronic pain, and in spasticity in multiple sclerosis. In addition, there is also some evidence suggesting a therapeutic potential of cannabis-based medicines in other indications including Tourette syndrome, spinal cord injury, Crohn’s disease, irritable bowel syndrome, and glaucoma. In several other indications, small uncontrolled and single-case studies reporting beneficial effects are available, for example in posttraumatic stress disorder, attention deficit hyperactivity disorder, and migraine. The most common side effects of THC and cannabis-based medicines rich in THC are sedation and dizziness (in more than 10% of patients), psychological effects, and dry mouth. Tolerance to these side effects nearly always develops within a short time. Withdrawal symptoms are hardly ever a problem in the therapeutic setting. In recent years there is an increasing interest in the medical use of CBD, which exerts no intoxicating side effects and is usually well-tolerated. Preliminary data suggest promising effects in the treatment of anxiety disorders, schizophrenia, dystonia, and some forms of epilepsy. This review gives an overview on clinical studies which have been published over the past 40 years.”

http://www.tandfonline.com/doi/abs/10.1080/07352689.2016.1265360?needAccess=true&journalCode=bpts20

“Review Identifies 140 Controlled Clinical Trials Related to Cannabis”  http://blog.norml.org/2017/06/04/review-identifies-140-controlled-clinical-trials-related-to-cannabis/

Cannabidiol in Medical Marijuana: Research Vistas and Potential Opportunities.

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“The high and increasing prevalence of medical marijuana consumption in the general population invites the need for quality evidence regarding its safety and efficacy. Herein, we synthesize extant literature pertaining to the phytocannabinoid cannabidiol (CBD) and its brain effects.

The principle phytocannabinoid Δ9-tetrahydrocannabinol (Δ9-THC) and CBD are the major pharmacologically active cannabinoids. The effect of CBD on brain systems as well as on phenomenological measures (e.g. cognitive function) are distinct and in many cases opposite to that of Δ9-THC.

Cannabidiol is without euphoriant properties, and exerts antipsychotic, anxiolytic, anti-seizure, as well as anti-inflammatory properties.

It is essential to parcellate phytocannabinoids into their constituent moieties as the most abundant cannabinoid have differential effects on physiologic systems in psychopathology measures. Disparate findings and reports related to effects of cannabis consumption reflect differential relative concentration of Δ9-THC and CBD.

Existing literature, notwithstanding its deficiencies, provides empirical support for the hypothesis that CBD may exert beneficial effects on brain effector systems/substrates subserving domain-based phenomenology. Interventional studies with purified CBD are warranted with a call to target-engagement proof-of-principle studies using the research domain criteria (RDoC) framework.” https://www.ncbi.nlm.nih.gov/pubmed/28501518

http://www.sciencedirect.com/science/article/pii/S1043661817303559

Cannabidiol Affects MK-801-Induced Changes in the PPI Learned Response of Capuchin Monkeys (Sapajus spp.).

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“There are several lines of evidence indicating a possible therapeutic action of cannabidiol (CBD) in schizophrenia treatment.

Studies with rodents have demonstrated that CBD reverses MK-801 effects in prepulse inhibition (PPI) disruption, which may indicate that CBD acts by improving sensorimotor gating deficits.

In the present study, we investigated the effects of CBD on a PPI learned response of capuchin monkeys (Sapajus spp.).

A total of seven monkeys were employed in this study. In Experiment 1, we evaluated the CBD (doses of 15, 30, 60 mg/kg, i.p.) effects on PPI. In Experiment 2, the effects of sub-chronic MK-801 (0.02 mg/kg, i.m.) on PPI were challenged by a CBD pre-treatment.

No changes in PPI response were observed after CBD-alone administration. However, MK-801 increased the PPI response of our animals.

CBD pre-treatment blocked the PPI increase induced by MK-801.

Our findings suggest that CBD’s reversal of the MK-801 effects on PPI is unlikely to stem from a direct involvement on sensorimotor mechanisms, but may possibly reflect its anxiolytic properties.”

 https://www.ncbi.nlm.nih.gov/pubmed/28289391