Cannabidiol, a plant-derived compound, is an emerging strategy for treating cognitive impairments: comprehensive review of randomized trials

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“Background: Finding new strategies to treat cognitive disorders is a challenging task. Medication must defeat the blood-brain barrier. Cannabidiol (CBD), a non-intoxicating compound of the cannabis plant, has gained recognition as a nutraceutical for its potential effectiveness in treating anxiety, oxidative stress, convulsions, and inflammation. However, the dose, tolerable upper intake, formulation, administration routes, comorbidities, diet, and demographic factors to reverse cognitive impairments have not been completely explored. Trials using CBD as a primary intervention have been conducted to alleviate cognitive issues. This review evaluates the benefits of CBD supplementation, research design, formulations, and outcomes reported in randomized clinical trials.

Methods: An evidence-based systematic literature review was conducted using PUBMED and the Florida International University Research Library resources. Fourteen randomized trials were selected for review, and their designs and outcomes were compared conceptually and in the form of resume tables.

Results: CBD showed improvement in anxiety and cognitive impairments in 9 out of 16 analyzed trials. However, the variability could be justified due to the diversity of the trial designs, underpowered studies, assayed population, uncontrolled results for comorbidities, medications, severity of drug dependence, compliances, and adherences. Overall, oral single doses of 200 mg-1,500 mg or vaporized 13.75 mg of CBD were shown to be effective at treating anxiety and cognition with a good safety profile and no drug addiction behaviors. Conversely, results that did not have a significant effect on treating cognitive impairments can be explained by various factors such as THC or other abuse drugs masking effect, low dose, and unknown purity of CBD. Furthermore, CBD shows potential properties that can be tested in the future for Alzheimer’s disease.

Conclusion: As medical cannabis becomes more accessible, it is essential to understand whether medication rich in CBD exerts a beneficial effect on cognitive disorders. Our study concludes that CBD is a promising candidate for treating neurocognitive disorders; however, more studies are required to define CBD as a therapeutic candidate for managing cognitive disorders.”

https://pubmed.ncbi.nlm.nih.gov/39323633/

“Cannabidiol (CBD), a phytocannabinoid, is derived from the cannabis plant.”

https://www.frontiersin.org/journals/pharmacology/articles/10.3389/fphar.2024.1403147/full

Bidirectional Effect of Long-Term Δ9-Tetrahydrocannabinol Treatment on mTOR Activity and Metabolome

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“Brain aging is associated with cognitive decline, reduced synaptic plasticity, and altered metabolism. The activity of mechanistic target of rapamycin (mTOR) has a major impact on aging by regulating cellular metabolism. Although reduced mTOR signaling has a general antiaging effect, it can negatively affect the aging brain by reducing synaptogenesis and thus cognitive functions. Increased mTOR activity facilitates aging and is responsible for the amnestic effect of the cannabinoid receptor 1 agonist Δ9-tetrahydrocannabinol (THC) in higher doses.

Long-term low-dose Δ9-THC had an antiaging effect on the brain by restoring cognitive abilities and synapse densities in old mice.

Whether changes in mTOR signaling and metabolome are associated with its positive effects on the aging brain is an open question. Here, we show that Δ9-THC treatment has a tissue-dependent and dual effect on mTOR signaling and the metabolome.

In the brain, Δ9-THC treatment induced a transient increase in mTOR activity and in the levels of amino acids and metabolites involved in energy production, followed by an increased synthesis of synaptic proteins. Unexpectedly, we found a similar reduction in the mTOR activity in adipose tissue and in the level of amino acids and carbohydrate metabolites in blood plasma as in animals on a low-calorie diet.

Thus, long-term Δ9-THC treatment first increases the level of energy and synaptic protein production in the brain, followed by a reduction in mTOR activity and metabolic processes in the periphery.

Our study suggests that a dual effect on mTOR activity and the metabolome could be the basis for an effective antiaging and pro-cognitive medication.”

https://pubmed.ncbi.nlm.nih.gov/39296258/

https://pubs.acs.org/doi/10.1021/acsptsci.4c00002

The Endocannabinoid System in Alzheimer’s Disease: A Network Meta-Analysis

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“The findings concerning the association between endocannabinoid system (ECS) and Alzheimer’s disease (AD) exhibited inconsistencies when examining the expression levels of endocannabinoids. This study aimed to provide a comprehensive summary of the studies regarding alterations of the ECS in AD.

Six databases were thoroughly searched for literature to select relevant studies investigating the ECS in AD, including changes in cannabinoid receptors (CB1R and CB2R), endocannabinoids (2-AG and AEA), and their associated enzymes (FAAH and MAGL). Traditional meta-analysis evaluated the expression levels of the ECS in AD, and the results showed no significant differences in ECS components between healthy controls and AD patients. However, subgroup analysis revealed significantly lower expression levels of CB1R in AD than in controls, particularly in studies using western blot (SMD = -0.88, p < 0.01) and in studies testing CB1R of frontal cortex (SMD = -1.09, p < 0.01). For studies using HPLC, the subgroup analysis indicated significantly higher 2-AG levels in AD than in controls (SMD = 0.46, p = 0.02). Network meta-analysis examined the rank of ECS alterations in AD compared to controls, and the findings revealed that 2-AG and MAGL exhibited the largest increase and CB1R showed the largest decrease relative to the control group.

Based on the findings of traditional meta-analysis and network meta-analysis, we proposed that AD patients may present decreased expression levels of CB1R and increased expression levels of 2-AG and its degrading enzyme MAGL.

Our results may contribute to the growing body of research supporting the therapeutic potential of ECS modulation in the management of AD.”

https://pubmed.ncbi.nlm.nih.gov/39245959/

https://onlinelibrary.wiley.com/doi/10.1002/jnr.25380

Medicinal cannabis extracts are neuroprotective against Aβ1-42-mediated toxicity in vitro

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“Background: Phytocannabinoids inhibit the aggregation and neurotoxicity of the neurotoxic Alzheimer’s disease protein β amyloid (Aβ). We characterised the capacity of five proprietary medical cannabis extracts, heated and non-heated, with varying ratios of cannabidiol and Δ9-tetrahydrocannabinol and their parent carboxylated compounds to protect against lipid peroxidation and Aβ-evoked neurotoxicity in PC12 cells.

Methods: Neuroprotection against lipid peroxidation and Aβ1-42-induced cytotoxicity was assessed using the thiazolyl blue tetrazolium bromide (MTT) assay. Transmission electron microscopy was used to visualise phytocannabinoid effects on Aβ1-42 aggregation and fluorescence microscopy.

Results: Tetrahydrocannabinol (THC)/tetrahydrocannabinolic acid (THCA)-predominant cannabis extracts demonstrated the most significant overall neuroprotection against Aβ1-42-induced loss of PC12 cell viability. These protective effects were still significant after heating of extracts, while none of the extracts provided significant neuroprotection to lipid peroxidation via tbhp exposure. Modest inhibition of Aβ1-42 aggregation was demonstrated only with the non-heated BC-401 cannabis extract, but overall, there was no clear correlation between effects on fibrils and conferral of neuroprotection.

Conclusions: These findings highlight the variable neuroprotective activity of cannabis extracts containing major phytocannabinoids THC/THCA and cannabidiol (CBD)/cannabidiolic acid (CBDA) on Aβ-evoked neurotoxicity and inhibition of amyloid β aggregation. This may inform the future use of medicinal cannabis formulations in the treatment of Alzheimer’s disease and dementia.”

https://pubmed.ncbi.nlm.nih.gov/39243211/

“With access to approved pathways increasing globally, medicinal cannabis formulations are increasingly being used to treat neuropsychiatric conditions. With laboratory and animal studies now showing benefits of cannabis and cannabinoids in treating neurodegenerative diseases, this study investigated whether whole cannabis extracts could protection neuronal cells against the toxicity of a signature Alzheimer’s disease protein, beta (β) amyloid.

We found that cannabis extracts afforded neuronal cells protection against amyloid β toxicity, mostly in extracts with the major phytocannabinoid, Δ9-THC, or its parent compound, Δ9-THC-COOH. These results suggest that medicinal cannabis may have potential in the further treatment of dementia.”

https://onlinelibrary.wiley.com/doi/10.1111/bcpt.14078


A combination of Δ9-tetrahydrocannabinol and cannabidiol modulates glutamate dynamics in the hippocampus of an animal model of Alzheimer’s disease

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“A combination of Δ9-tetrahydrocannabinol (Δ9-THC) and cannabidiol (CBD) at non-psychoactive doses was previously demonstrated to reduce cognitive decline in APP/PS1 mice, an animal model of Alzheimer’s disease (AD). However, the neurobiological substrates underlying these therapeutic properties of Δ9-THC and CBD are not fully understood.

Considering that dysregulation of glutamatergic activity contributes to cognitive impairment in AD, the present study evaluates the hypothesis that the combination of these two natural cannabinoids might reverse the alterations in glutamate dynamics within the hippocampus of this animal model of AD.

Interestingly, our findings reveal that chronic treatment with Δ9-THC and CBD, but not with any of them alone, reduces extracellular glutamate levels and the basal excitability of the hippocampus in APP/PS1 mice.

These effects are not related to significant changes in the function and structure of glutamate synapses, as no relevant changes in synaptic plasticity, glutamate signaling or in the levels of key components of these synapses were observed in cannabinoid-treated mice. Our data instead indicate that these cannabinoid effects are associated with the control of glutamate uptake and/or to the regulation of the hippocampal network.

Taken together, these results support the potential therapeutic properties of combining these natural cannabinoids against the excitotoxicity that occurs in AD brains.”

https://pubmed.ncbi.nlm.nih.gov/39232876/

https://www.neurotherapeuticsjournal.org/article/S1878-7479(24)00126-0/fulltext

A Comprehensive Exploration of the Multifaceted Neuroprotective Role of Cannabinoids in Alzheimer’s Disease across a Decade of Research

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“Alzheimer’s disease (AD), a progressive neurodegenerative disorder, manifests through dysregulation of brain function and subsequent loss of bodily control, attributed to β-amyloid plaque deposition and TAU protein hyperphosphorylation and aggregation, leading to neuronal death.

Concurrently, similar cannabinoids to the ones derived from Cannabis sativa are present in the endocannabinoid system, acting through receptors CB1R and CB2R and other related receptors such as Trpv-1 and GPR-55, and are being extensively investigated for AD therapy.

Given the limited efficacy and adverse effects of current available treatments, alternative approaches are crucial. Therefore, this review aims to identify effective natural and synthetic cannabinoids and elucidate their beneficial actions for AD treatment. PubMed and Scopus databases were queried (2014-2024) using keywords such as “Alzheimer’s disease” and “cannabinoids”.

The majority of natural (Δ9-THC, CBD, AEA, etc.) and synthetic (JWH-133, WIN55,212-2, CP55-940, etc.) cannabinoids included showed promise in improving memory, cognition, and behavioral symptoms, potentially via pathways involving antioxidant effects of selective CB1R agonists (such as the BDNF/TrkB/Akt pathway) and immunomodulatory effects of selective CB2R agonists (TLR4/NF-κB p65 pathway).

Combining anticholinesterase properties with a cannabinoid moiety may enhance therapeutic responses, addressing cholinergic deficits of AD brains. Thus, the positive outcomes of the vast majority of studies discussed support further advancing cannabinoids in clinical trials for AD treatment.”

https://pubmed.ncbi.nlm.nih.gov/39201317/

“As understood from the above, cannabinoids exhibit efficacy in reversing several of the manifestations of AD.”

https://www.mdpi.com/1422-0067/25/16/8630

Bidirectional Effect of Long-Term Δ9-Tetrahydrocannabinol Treatment on mTOR Activity and Metabolome

Go to ACS Pharmacology & Translational Science

“Brain aging is associated with cognitive decline, reduced synaptic plasticity, and altered metabolism. The activity of mechanistic target of rapamycin (mTOR) has a major impact on aging by regulating cellular metabolism. Although reduced mTOR signaling has a general antiaging effect, it can negatively affect the aging brain by reducing synaptogenesis and thus cognitive functions.

Increased mTOR activity facilitates aging and is responsible for the amnestic effect of the cannabinoid receptor 1 agonist Δ9-tetrahydrocannabinol (THC) in higher doses. Long-term low-dose Δ9-THC had an antiaging effect on the brain by restoring cognitive abilities and synapse densities in old mice. Whether changes in mTOR signaling and metabolome are associated with its positive effects on the aging brain is an open question.

Here, we show that Δ9-THC treatment has a tissue-dependent and dual effect on mTOR signaling and the metabolome. In the brain, Δ9-THC treatment induced a transient increase in mTOR activity and in the levels of amino acids and metabolites involved in energy production, followed by an increased synthesis of synaptic proteins. Unexpectedly, we found a similar reduction in the mTOR activity in adipose tissue and in the level of amino acids and carbohydrate metabolites in blood plasma as in animals on a low-calorie diet.

Thus, long-term Δ9-THC treatment first increases the level of energy and synaptic protein production in the brain, followed by a reduction in mTOR activity and metabolic processes in the periphery. Our study suggests that a dual effect on mTOR activity and the metabolome could be the basis for an effective antiaging and pro-cognitive medication.”

https://pubs.acs.org/doi/10.1021/acsptsci.4c00002

“Low-dose long-term administration of cannabis compound reverses brain aging”

“Anti-ageing and increased mental capacity through cannabis”

https://www.uni-bonn.de/en/news/164-2024#:~:text=%22We%20concluded%20that%20long%2Dterm,%2C%22%20says%20Bilkei%2DGorzo.

In the weeds: A comprehensive review of cannabis; its chemical complexity, biosynthesis, and healing abilities

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“For millennia, various cultures have utilized cannabis for food, textile fiber, ethno-medicines, and pharmacotherapy, owing to its medicinal potential and psychotropic effects. An in-depth exploration of its historical, chemical, and therapeutic dimensions provides context for its contemporary understanding. The criminalization of cannabis in many countries was influenced by the presence of psychoactive cannabinoids; however, scientific advances and growing public awareness have renewed interest in cannabis-related products, especially for medical use.

Described as a ‘treasure trove,’ cannabis produces a diverse array of cannabinoids and non-cannabinoid compounds. Recent research focuses on cannabinoids for treating conditions such as anxiety, depression, chronic pain, Alzheimer’s, Parkinson’s, and epilepsy. Additionally, secondary metabolites like phenolic compounds, terpenes, and terpenoids are increasingly recognized for their therapeutic effects and their synergistic role with cannabinoids. These compounds show potential in treating neuro and non-neuro disorders, and studies suggest their promise as antitumoral agents. This comprehensive review integrates historical, chemical, and therapeutic perspectives on cannabis, highlighting contemporary research and its vast potential in medicine.”

https://pubmed.ncbi.nlm.nih.gov/39056093/

https://www.sciencedirect.com/science/article/pii/S2214750024000684?via%3Dihub

Cannabidiol and Alzheimer’s disease

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“Alzheimer’s disease (AD) stands as the most prevalent form of neuropsychiatric disorder among the elderly population, impacting a minimum of 50 million individuals worldwide. Current pharmacological treatments rely on the prescribing cholinesterase inhibitors and memantine. However,recently anecdotal findings based on low-quality real-world data had prompted physicians, patients, and their relatives to consider the use of cannabinoids, especially Cannabidiol (CBD), for alleviating of AD symptoms.

CBD the primary non-psychotomimetic compound found in the Cannabis sp. plant, exhibits promising therapeutic potential across various clinical contexts. Pre-clinical and in vitro studies indicate that CBD could mitigate cognitive decline and amyloid-beta-induced neurodegeneration by modulating oxidative stress and neuroinflammation.

In addition, CBD demonstrates significant effects in promoting neuroplasticity, particularly in brain regions such as the hippocampus. However, the available clinical evidence presents conflicting results, and no randomized placebo-controlled trials have been published to date.

In conclusion, although pre-clinical and in vitro studies offer encouraging insights into the potential benefits of CBD in AD models, new and well-designed clinical trials are imperative to ascertain the clinical relevance of CBD use in the management of AD symptoms, especially in comparison to conventional treatments.”

https://pubmed.ncbi.nlm.nih.gov/39029982/

https://www.sciencedirect.com/science/article/abs/pii/S0074774224000667?via%3Dihub


Cannabidiol and Neurodegeneration: From Molecular Mechanisms to Clinical Benefits

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“Neurodegenerative disorders (NDs) such as Alzheimer’s disease, Parkinson’s disease, Huntington’s disease, multiple sclerosis, and amyotrophic lateral sclerosis are severe and life-threatening conditions in which significant damage of functional neurons occurs to produce malfunction of psycho-motor functions. NDs are an important cause of death in the elderly population worldwide. These disorders are commonly associated with the progression of age, oxidative stress, and environmental pollutants, which are the major etiological factors. Abnormal aggregation of specific proteins such as α-synuclein, amyloid-β, huntingtin, and tau, and accumulation of its associated oligomers in neurons are the hallmark pathological features of NDs. Existing therapeutic options for NDs are only symptomatic relief and do not address root-causing factors, such as protein aggregation, oxidative stress, and neuroinflammation.

Cannabidiol is a non-psychotic natural cannabinoid obtained from Cannabis sativa that possesses multiple pharmacological actions, including antioxidant, anti-inflammatory, and neuroprotective effects in various NDs and other neurological disorders both in vitro and in vivo.

Cannabidiol has gained attention as a promising therapeutic drug candidate for the management of neurodegenerative disorders, such as Alzheimer’s disease and Parkinson’s disease, by inhibiting protein aggregation, free radicals, and neuroinflammation. In parallel, CBD has shown positive results in other neurological disorders, such as epilepsy, depression, schizophrenia, and anxiety, as well as adjuvant treatment with existing standard therapeutic agents. Hence, the present review focuses on exploring the possible molecular mechanisms in controlling various neurological disorders as well as its clinical applications in NDs including epilepsy, depression and anxiety. In this way, the current review will serve as a standalone reference for the researchers working in this area.”

https://pubmed.ncbi.nlm.nih.gov/38969143/

https://www.sciencedirect.com/science/article/abs/pii/S1568163724002046?via%3Dihub