CBD Gummies Hallucinations


Buy CBD Oil Online

Cannabis use is linked to psychosis, but only a small number of users will experience it. People using marijuana edibles should be cautious. Edibles are 268 times more likely than inhaled marijuana to cause users in Colorado to seek help at an ER Cannabis Dopaminergic Effects Induce Hallucinations in a Patient with Parkinson’s Disease 1 Office of Translational Research and Residency Programs, Tabula Rasa HealthCare, Moorestown, NJ 08057,

Cannabis and psychosis: what is the link and who is at risk?

Jerome Sarris is supported by an NHMRC Clinical Research Fellowship (APP1125000) and conducts psychotropic plant and nutraceutical research. He has been the past recipient of institutional grants and consultancy payments from this work. He may potentially provide in the future paid consultation to companies developing or selling medicinal cannabis products. He is affiliated with an academic collaboration: The Australian Medicinal Cannabis Research and Education (AMCREC) which conducts research on cannabis and cannabinoids (www.AMCREC.org).

Joseph Firth is supported by a Blackmores Institute Fellowship.


Western Sydney University provides funding as a member of The Conversation AU.

There has been a recent global rise in “green fever”, with various jurisdictions either decriminalising or legalising cannabis.

But alongside relaxing the rules comes concern about the health implications of cannabis use. We often hear of a link between cannabis use and psychosis. So how strong is the link, and who is at risk?

What is psychosis?

There’s consistent evidence showing a relationship over time between heavy or repeated cannabis use (or those diagnosed with cannabis use disorder) and an experience of psychosis for the first time.

Psychotic disorders are severe mental health conditions. They’re characterised by a “loss of contact with reality”, where the individual loses the ability to distinguish what’s real from what’s not. Psychotic symptoms can include visual hallucinations, hearing voices, or pervasive delusional thinking.

These can often present as a “psychotic episode” – which is a relatively sudden worsening of psychotic symptoms over a short time-frame, frequently resulting in hospitalisation.

The heaviest users of cannabis are around four times as likely to develop schizophrenia (a psychotic disorder that affects a person’s ability to think, feel and behave clearly) than non-users. Even the “average cannabis user” (for which the definition varies from study to study) is around twice as likely as a non-user to develop a psychotic disorder.

Furthermore, these studies found a causal link between tetrahydrocannabinol (THC – the plant chemical which elicits the “stoned” experience) and psychosis. This means the link is not coincidental, and one has actually caused the other.

Who is at risk?

People with certain gene variants seem to be at higher risk. However our understanding of these factors is still limited, and we’re unable to use genetic information alone to determine if someone will or won’t develop psychosis from cannabis use.

Those with these genetic variants who have also experienced childhood trauma, or have a paranoid personality type, are even more at-risk. So too are adolescents and young adults, who have growing brains and are at an age where schizophrenia is more likely to manifest.

The type of cannabis material being used (or the use of synthetic cannabinoids, known as “spice”) may also increase the risk of psychosis. As mentioned above, this is due to the psychological effects of the chemical THC (one of over 140 cannabinoids found in the plant).

Even healthy people given THC can experience psychotic symptoms including paranoia. from www.shutterstock.com

This compound may actually mimic the presentation of psychotic symptoms, including paranoia, sensory alteration, euphoria, and hallucinations. In laboratory-based research, even healthy people may exhibit increased symptoms of psychosis when given THC compounds, with more severe effects observed in people with schizophrenia.

Many cannabis strains contain high amounts of THC, found in plant varieties such as one called “skunk”. These are popular with consumers due to the “high” it elicits. However with this goes the increased risk of paranoia, anxiety, and psychosis.

But can’t cannabis also be good for mental health?

Ironically, one compound found in cannabis may actually be beneficial in treating psychosis. In contrast to THC, a compound called cannabidiol (CBD) may provide a buffering effect to the potentially psychosis-inducing effects of THC.

This may occur in part due to its ability to partially block the same brain chemical receptor THC binds with. CBD can also inhibit the breakdown of a brain chemical called “anandamide,” which makes us feel happy. Incidentally, anandamide is also found in chocolate and is aptly named after the Sanskrit word meaning “bliss”.

CBD extracted from cannabis and used in isolation is well-tolerated with minimal psychoactive effects. In other words, it doesn’t make a person feel “high”. Some studies have found CBD is actually beneficial in improving the symptoms of schizophrenia. But one more recent study showed no difference in the effects of CBD compared to a dummy pill on symptoms of schizophrenia.

Perhaps this means CBD benefits a particular biological sub-type of schizophrenia, but we’d need further study to find out.

Would legalising make a difference?

It’s important to note most studies finding a causal link between cannabis use and psychosis examined the use of illicit cannabis, usually from unknown origins. This means the levels of THC were unrestricted, and there’s a possibility of synthetic adulterants, chemical residues, heavy metals or other toxins being present due to a lack of quality assurance practices.

In the future, it’s possible that standardised novel “medicinal cannabis” formulations (or isolated compounds) may have negligible effects on psychosis risk.

Until then though, we can safely say given the current weight of evidence, illicit cannabis use can increase the risk of an acute psychotic episode. And this subsequently may also increase the chances of developing schizophrenia. This is particularly true when high-THC strains (or synthetic versions) are used at high doses in growing adolescent brains.

Five things you should know about marijuana edibles

The Rocky Mountains beckon. So, too, do the pot shops.

Many visitors to Colorado come for the state’s natural beauty, but also are curious about marijuana dispensaries.

Marijuana edibles can send people to the ER if they take too much or have a bad reaction. Photo: Getty Images.

Before indulging in edibles, take some advice from Dr. Andrew Monte, an emergency medicine and toxicology specialist at UCHealth University of Colorado Hospital and an associate professor at the University of Colorado School of Medicine. Monte cares for patients in the ER and has done extensive studies on marijuana use.

His advice: be very cautious about edibles. While Monte says some edibles may help patients for medical problems like pain, they’re not a good choice for recreational users, especially for novices who haven’t used weed or tried edibles in the past. For some people, edibles can cause scary symptoms like a racing heart, anxiety, and hallucinations.

If you are planning to try marijuana edibles, here are five things you should know:

  • Start small. Go slow.Edibles affect individuals in different ways. It can take up to four hours for the high from an edible to take effect. The biggest mistake new users make is continuing to ingest edibles if they don’t feel high right away. Then, the high hits hard and can last for several hours, leading some people to feel sick or anxious and seek help in ERs.
  • Edibles are much more likely to cause people to seek medical help compared with inhaled marijuana. In a new study to be released in the Annals of Internal Medicine, Monte found that ER visits due to edibles were 33 times higher than expected, when controlled for product sales in the state. That’s true even though inhaled forms of marijuana are much more common than edibles.
  • The state-recommended dose for edibles is 10 mg, but even that dose can make some people feel sick or anxious. Monte has had patients who have consumed the recommended dosage and still suffered negative side effects. He does not recommend recreational use of edibles. But, if people are trying them, they should start with no more than 2.5 to 5 mg. and see how they respond before eating or drinking more. Never mix edibles with alcohol or other drugs.
  • The negative side effects from edibles can be scary. For those who have a negative reaction to edibles, the symptoms can include a racing heart, excessive sweating, anxiety, paranoia, hallucinations and delusions. “They can cause people to freak out. Clearly edibles have a more severe toxicity than inhaled forms and the effects are psychiatric in nature,” Monte said. Sometimes people flying out of Colorado decide to finish all the edibles they’ve purchased before heading to the airport. Then, the high hits right when they’re going through security or trying to board a plane. Some end up in the ER instead of catching a flight home. In extreme cases, three deaths in Colorado have been linked to consumption of marijuana edibles. A l9-year-old college student from Wyoming jumped to his death after consuming six times the recommended dosage of edibles. A 23-year-old graduate student killed himself in Keystone and his family blamed the marijuana edibles he consumed. And a Denver man killed his wife after consuming as much as 50 mg. of edibles. He blames the edibles for his psychosis and violence.
  • Kids and dogs accidentally ingest edibles. Safe storage is essential. Both toddlers and canines are notorious for popping whatever they find into their mouths. And edibles are designed to taste and smell good. They come in a variety of forms from brownies, cookies and candies to drinks and popcorn. Both veterinarians and doctors in Colorado, like Monte’s colleague at Children’s Hospital Colorado, Dr. George “Sam” Wang, have seen an increase in accidental poisonings linked to edibles. Users should keep edibles locked up and out of reach from children and pets.
See also  CBD Oil Dose For Neuropathic Pain

About the author

Katie Kerwin McCrimmon, UCHealth

Katie Kerwin McCrimmon is a proud Colorado native. She attended Colorado College, thanks to a merit scholarship from the Boettcher Foundation, and worked as a park ranger in Rocky Mountain National Park during summer breaks from college. She is also a storyteller. She loves getting to know UCHealth patients and providers and sharing their inspiring stories.

Katie spent years working as a journalist at the Rocky Mountain News and was a finalist with a team of reporters for the Pulitzer Prize for their coverage of a deadly wildfire in Glenwood Springs in 1994. Katie was the first reporter in the U.S. to track down and interview survivors of the tragic blaze, which left 14 firefighters dead.

She covered an array of beats over the years, including the environment, politics, education and criminal justice. She also loved covering stories in Congress and at the U.S. Supreme Court during a stint as the Rocky’s reporter in Washington, D.C.

Katie then worked as a reporter for an online health news site before joining the UCHealth team in 2017.

Katie and her husband Cyrus, a Pulitzer Prize-winning photographer, have three children. The family loves traveling together anywhere from Glacier National Park to Cuba.

Cannabis Dopaminergic Effects Induce Hallucinations in a Patient with Parkinson’s Disease

1 Office of Translational Research and Residency Programs, Tabula Rasa HealthCare, Moorestown, NJ 08057, USA; [email protected] (K.P.); [email protected] (N.D.T.-P.); [email protected] (A.M.); [email protected] (N.A.)

David Thacker

2 Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Tabula Rasa HealthCare, Orlando, FL 32827, USA; [email protected] (D.T.); [email protected] (J.T.)

Nicole Del Toro-Pagán

1 Office of Translational Research and Residency Programs, Tabula Rasa HealthCare, Moorestown, NJ 08057, USA; [email protected] (K.P.); [email protected] (N.D.T.-P.); [email protected] (A.M.); [email protected] (N.A.)

Abeer Hanna

3 Viecare Butler, Program of All-Inclusive Care for the Elderly (PACE), Butler, PA 16001, USA; [email protected]

Jacques Turgeon

2 Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Tabula Rasa HealthCare, Orlando, FL 32827, USA; [email protected] (D.T.); [email protected] (J.T.)

4 Faculty of Pharmacy, Université de Montréal, Montréal, QC H3C 3J7, Canada

Adriana Matos

1 Office of Translational Research and Residency Programs, Tabula Rasa HealthCare, Moorestown, NJ 08057, USA; [email protected] (K.P.); [email protected] (N.D.T.-P.); [email protected] (A.M.); [email protected] (N.A.)

Nishita Amin

1 Office of Translational Research and Residency Programs, Tabula Rasa HealthCare, Moorestown, NJ 08057, USA; [email protected] (K.P.); [email protected] (N.D.T.-P.); [email protected] (A.M.); [email protected] (N.A.)

Veronique Michaud

2 Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Tabula Rasa HealthCare, Orlando, FL 32827, USA; [email protected] (D.T.); [email protected] (J.T.)

4 Faculty of Pharmacy, Université de Montréal, Montréal, QC H3C 3J7, Canada

1 Office of Translational Research and Residency Programs, Tabula Rasa HealthCare, Moorestown, NJ 08057, USA; [email protected] (K.P.); [email protected] (N.D.T.-P.); [email protected] (A.M.); [email protected] (N.A.)

2 Tabula Rasa HealthCare, Precision Pharmacotherapy Research and Development Institute, Tabula Rasa HealthCare, Orlando, FL 32827, USA; [email protected] (D.T.); [email protected] (J.T.)

3 Viecare Butler, Program of All-Inclusive Care for the Elderly (PACE), Butler, PA 16001, USA; [email protected]

Licensee MDPI, Basel, Switzerland. This article is an open access article distributed under the terms and conditions of the Creative Commons Attribution (CC BY) license (https://creativecommons.org/licenses/by/4.0/).

Associated Data


Cannabis products that contain the tetrahydrocannabinol (THC) cannabinoid are emerging as promising therapeutic agents for the treatment of medical conditions such as chronic pain. THC elicits psychoactive effects through modulation of dopaminergic neurons, thereby altering levels of dopamine in the brain. This case report highlights the complexity associated with medicinal cannabis and the health risks associated with its use. A 57-year-old male with Parkinson’s disease was experiencing worsening tremors and vivid hallucinations despite therapy optimization attempts. It was discovered that the patient took cannabis for chronic back pain, and a pharmacogenomics (PGx) test indicated the presence of variants for the COMT and HTR2A genes. These variants could increase dopamine levels and predispose patients to visual hallucinations. Once the cannabis was discontinued, the patient’s hallucinations began to slowly dissipate. Cannabis use continues to expand as it gains more acceptance legally and medicinally, but cannabis can affect the response to drugs. This patient case suggests that cannabis use in combination with dopamine-promoting drugs, especially in a patient with genetic variants, can increase the risk for vivid hallucinations. These conditions support the importance of considering herb–drug interactions and PGx data when performing a medication safety review.

1. Introduction

The use of medical cannabis has steadily gained popularity over the last several years. Cannabis has demonstrated therapeutic effects with different cannabinoids derived from the cannabis plant, specifically tetrahydrocannabinol (THC) and cannabidiol (CBD), which are being utilized for several medical conditions by providing analgesic, antispasmodic, and antiemetic properties [1,2,3]. While the role of cannabis in medicine continues to expand, it is imperative to consider cannabis effects and potential drug interactions. Research has demonstrated that THC and CBD are substrates of the cytochrome P450 (CYP) enzymes CYP2C9 and CYP2C19, and thus, will increase the risk for drug–drug interactions [4]. Additionally, THC has been shown to elicit its psychoactive effects through modulation of dopaminergic neurons, thereby altering levels of dopamine in different areas of the brain [5].

Appropriate dopamine levels are vital, as the nervous system utilizes dopamine for the regulation of several physiological functions (e.g., mood, motor, cognitive) [6]. Enzymes and transporters, such as the catechol-O-methyltransferase (COMT) enzyme and dopamine transporters, help regulate the level of dopamine in the synapses [6]. The COMT gene is responsible for producing the COMT enzyme, which acts as a metabolizing enzyme for dopamine [6]. Therefore, genetic alterations of COMT and other relevant genes affecting dopamine can potentially alter how an individual responds to THC [7].

Low levels of dopamine in specific brain regions have been found to be associated with certain conditions, such as Parkinson’s disease (PD). PD is a neurodegenerative disease caused by the death of dopamine-producing neurons in the substantia nigra, which is a part of the midbrain responsible for coordinating movement [8]. Neuronal death in this region results in low dopamine concentrations; therefore, treatment strategies for PD often involve initiating medications (e.g., carbidopa-levodopa, ropinirole, entacapone) that result in increased concentrations of dopamine to improve movement control [8]. Concomitant intake of cannabis and drugs used in the treatment of PD can significantly modulate dopamine concentrations. The case described herein demonstrates the importance of considering the pharmacokinetic and pharmacodynamic effects of cannabis and an individual’s pharmacogenomic (PGx) data when evaluating a patient’s medication regimen for therapeutic response and/or adverse drug events.

2. Case Presentation

A 57-year-old male with a past diagnosis of PD began treatment with a new primary care physician (PCP). In addition to PD, the patient’s past medical history includes spinal stenosis, vitamin D deficiency, frequent falls, a history of nicotine and alcohol dependence, mild kidney disease, and chronic neck, back, and shoulder pain. The patient had spinal surgery approximately two years ago, during which he developed complications (i.e., delirium) from anesthesia, causing him to remain hospitalized for an additional month. During his initial meeting with the PCP, the patient reported experiencing worsening tremors, body pain, and vivid visual hallucinations encompassing small children and flying objects, which the patient claimed to have been seeing for over two years. This patient was also prescribed rivastigmine, as Lewy body dementia was recently included as a differential diagnosis due to the presence of these hallucinations. Upon evaluation of the patient’s past medical history and medications, changes were made to his drug regimen to better control his symptoms, which included increasing the doses for carbidopa-levodopa and rivastigmine ( Figure 1 ). The patient’s tremors began to slowly diminish with his new medication regimen; however, his vivid hallucinations were still present. Upon further inquisition at a subsequent visit, the PCP discovered that approximately two years ago the patient had been advised to chronically use cannabis to manage his chronic back pain. On average, the patient reported smoking approximately 3 g of cannabis per week. The new PCP promptly recommended the cessation of cannabis, as its use with other medications could be contributing to his vivid hallucinations. The patient’s interdisciplinary team continued to evaluate his hallucinations and tremors after discontinuation of cannabis, which was confirmed with a negative drug screen. The patient reported that his hallucinations began to diminish slowly over time. As more time elapsed, his hallucinations of children and flying objects changed to seeing only floating dots. Considering the improvement in hallucinations was observed following discontinuation of cannabis, rivastigmine was discontinued as it was determined that the patient’s hallucinations were likely not due to Lewy body dementia. During a follow-up encounter two months later, the patient reported that his hallucinations had disappeared, and control of his tremors had improved further. The clinical pharmacist recommended dose increases of carbidopa-levodopa to help control his tremors still present early in the morning ( Figure 1 ).

Drug and Symptom Change Timeline. 1 Shaded area in the chart represents when hallucinations were experienced by the patient. Shades of gray are associated with the presence of vivid or fewer hallucinations and which medications are administered at that time. 2 Period when tremor symptoms were experienced by the patient. Abbreviations: QD: once a day, BID: twice a day, TID: three times a day, QID: four times a day, HS: at bedtime.

A PGx test was also ordered to help determine if a genetic component could explain why this patient experienced such vivid hallucinations from cannabis. Upon reception of the PGx results ( Table 1 ), the pharmacist observed that the patient was homozygous for the COMT variant (rs4680 AA (Met/Met); this variant is associated with low enzyme (COMT) activity due to a decreased production of the enzyme. Such a decrease in COMT activity is associated with higher levels of catecholamines (i.e., dopamine) in the brain.

Table 1

Patient’s Pharmacogenomics Test Results.

Gene Genotype Phenotype
CYP1A2 1 *1F|*1F Possible Normal
CYP2B6 *1|*1 Normal Metabolizer
CYP2C9 *1|*1 Normal Metabolizer
CYP2C19 *1|*1 Normal Metabolizer
CYP2D6 *1|*4 Intermediate Metabolizer
CYP3A4 2 *1|*1 Undetermined
CYP3A5 *3|*3 Poor Expresser
COMT rs4680 AA (Met/Met) Low Activity
DRD2 rs1799978 AA Normal Receptor
HTR2A rs7997012 GG Altered Receptor Function
See also  CBD Oil Distillation Process

1 Common variants in CYP1A2 gene reflect its inducibility. CYP1A2 genetic variations, without the presence of induction (e.g., smoking, concomitant CYP1A2 inducers), have not been demonstrated to clinically alter the activity of CYP1A2 [9]. 2 CYP3A4 gene shows some genetic variations and most variants have not been demonstrated to clinically alter the activity of CYP3A4. Many of the variants are extremely rare, making it difficult to derive a phenotype based on genetic results [10].

To manage his chronic pain (after cessation of cannabis), the patient was prescribed celecoxib and lidocaine topical patches for back, neck, and shoulder pain. However, his PCP determined that additional medication for pain control was warranted. Given that patient was identified as a CYP2D6 intermediate metabolizer ( Table 1 ; CYP2D6*1/*4), the clinical pharmacist recommended prescribing an opioid that does not utilize the CYP2D6 pathway (e.g., morphine) to decrease the risk of pharmacotherapy failure and/or possible adverse drug events.

3. Discussion

The use of cannabis products for medical purposes continues to expand as research develops. The patient under consideration in this case report was initially recommended cannabis for analgesia due to chronic back pain. Guidance is currently available regarding medical cannabis use for the treatment of chronic pain, suggesting that cannabis-based drugs can be considered when all other treatment options have failed [1]. CBD and THC are the two most prominent cannabinoids found in cannabis and have been used to treat multiple sclerosis spasms, neuropathic and cancer pain, nausea, and insomnia [4]. CBD has been utilized as an anxiolytic and the U.S. Food and Drug Administration has approved the CBD oral solution (Epidiolex ® ) as a treatment option for epilepsy [4,11]. While research has provided guidance on managing chronic pain with cannabis, guidance is not available regarding use in other conditions. However, research has shown that cannabis use can cause hallucinations in patients with PD, thus the appropriateness of cannabis use should be evaluated [1,12].

THC is the main psychoactive cannabinoid in cannabis as both the parent molecule and its 11-hydroxy-delta-9-tetrahydrocannabinol (11-OH-THC) metabolite produce euphoric effects [13]. THC does not provide analgesic effects, but its 11-carboxy-delta-9-tetrahydrocannabinol (11-COOH-THC, psychotropically inactive) metabolite possesses anti-inflammatory and analgesic properties [13]. The non-psychoactive analogue of THC, CBD, another cannabinoid found in cannabis, has also shown analgesic and anti-inflammatory effects [14].

THC is metabolized by CYP enzymes in the liver, particularly CYP3A4 and CYP2C9 [4,15]. CBD is mainly metabolized by CYP3A4 and CYP2C19, and at higher oral doses (5 mg/kg/day), can inhibit CYP2C9 and to a lesser extent CYP1A2 [8,11,16]. Concomitant administration of prescribed medications with cannabis engenders a risk of potential herb–drug CYP450 interactions ( Figure 2 ). Therefore, any drug with a stronger affinity for the CYP2C9, CYP2C19 or CYP3A4 enzymes than THC or CBD, if administered at the same time, could affect their disposition and result in an herb–drug interaction [4,17]. These interactions could lead to increased CBD or THC concentrations and possibly lower concentrations of THC’s metabolites [4,17]. Furthermore, CYP2C9 and CYP2C19 are both polymorphic enzymes with differing functions that could modulate cannabis exposure if genetic variants are present (which was excluded as a contributing factor for this case) ( Table 1 ) [15,18].

Summary of Affinity and CYP Metabolic Pathways. 1 Treatment with celecoxib began after the cessation of cannabis. Abbreviations: CBD: cannabidiol, CYP: Cytochrome P450, THC: tetrahydrocannabinol.

Although studies investigating the use of cannabis for pain demonstrated mixed results, there is emerging evidence supporting the benefit of cannabis for pain [19,20,21]. Numerous factors can explain discrepancies between study results such as pain models, healthy subjects vs. patients, routes of administration (inhalation vs. oral), and sources of the product [19,20,21]. The utility of cannabis use remains under debate as there is no approved indication, formulation, or dosage for pain. Further research is needed to better understand the efficacy, dose–response effects, routes of administration and side-effect or safety profiles associated with such products. In general, inhaled cannabis (smoking and vaping) is associated with a quicker onset of action, while oral administration of cannabis has a slower or delayed onset of action, and it is exposed to the intestinal-hepatic first-pass effect [4]. Side effects and safety profiles should be considered for both routes of administrations.

PD is characterized by the death of dopamine-producing neurons, specifically in the substantia nigra, which impacts an individual’s ability to control their movements [8]. Treatment strategies to combat PD motor symptoms include drugs such as dopamine precursors (e.g., carbidopa-levodopa), dopamine agonists (e.g., ropinirole), COMT inhibitors (e.g., entacapone), and monoamine oxidase B inhibitors (e.g., rasagiline) [8]. Additionally, visual hallucinations are a common non-motor symptom observed in patients with PD, and they typically result from long-term use or dose increases of PD drugs [8]. The cause of these particular hallucinations can be multifactorial but there is evidence attributing them to high levels of dopamine [22]. In this patient’s case, the medical team considered the patient’s PD medication regimen and disease progression when attempting to identify the cause of hallucinations while managing worsening tremors. The clinical presentation suggested that the patient was not receiving enough dopamine from his medications to control his tremors supporting the proposed increased dose of carbidopa-levodopa. In addition, the dose of rivastigmine was increased to improve cognitive and functional abilities and diminish visual hallucinations [23]. These pharmacotherapy interventions improved his tremors; however, his vivid hallucinations were not alleviated which warranted further consideration.

The endocannabinoid system (ECS) is an essential regulator of dopamine levels [4,24]. The ECS is a neuromodulatory system able to regulate several neurons (e.g., dopamine) [4,24,25]. THC acts as a receptor agonist for receptors in the ECS, known as cannabinoid receptor 1 (CB1R) and cannabinoid receptor 2 (CB2R) [4,5,24]. CB1Rs are found predominately in the brain and are located on many neurons presynaptically, as well as postsynaptically [26]. In regards to dopamine neurons, inhibitory neurotransmitters such as gamma-aminobutyric acid (GABA) act on dopamine neurons to regulate and reduce dopamine release into the synapses [5,24,25]. When CB1Rs on presynaptic neurons are activated, inhibitory neurotransmitter levels are reduced and dopamine levels increase [5,24,25]. When THC binds in the striatum and cortex, the euphoric feeling associated with THC occurs; however, abnormal levels of dopamine in the striatal and limbic regions of the brain have been observed in patients experiencing psychotic symptoms, including hallucinations [5,24,27].

A small percentage of people have been shown to experience psychotomimetic effects with low-dose THC in the presence of genetic polymorphisms [7]. The COMT gene is responsible for producing the COMT enzyme, which acts as a metabolizing enzyme for dopamine [6]. The COMT enzyme demonstrates the importance of dopamine regulation within the prefrontal cortex, as there are fewer available dopamine transporters in this region of the brain [28]. In COMT, a common polymorphism can occur due to a change from the amino acid valine (Val) to a methionine (Met) [Val158Met], which results in a reduction in dopamine metabolism [29]. Therefore, carriers of the Met variant experience higher dopamine concentrations in synapses [29]. Studies in healthy individuals with the COMT wild-type have been shown to metabolize dopamine up to four times faster than those with COMT Met/Met, deeming individuals homozygous for Met as having low COMT enzyme activity [28]. Interestingly, the patient’s PGx results ( Table 1 ) reported a genotype for COMT Met/Met, therefore higher levels of dopamine in his synapses would be expected.

Research has been conducted to evaluate the effects of the COMT Val158Met polymorphism and the use of cannabis on the risk for psychosis [28,30]. In healthy individuals, there is an observed correlation between cannabis use in those with COMT Val/Val and increased risk for psychosis [28,30]. This genotype is also associated with lower levels of prefrontal dopamine; therefore, this observation is thought to be due to higher levels of phasic dopamine transmission, which aids in the development of psychotic symptoms [28]. Additionally, a previous study evaluated patients with PD and their subsequent reactions to cannabis use, reporting that one out of five patients experienced hallucinations [12]. Given these studies and considering THC can also increase dopamine levels, extra care should be exercised in carriers of the Met variant in regards to cannabis use [31].

Furthermore, this patient was reported to have a single nucleotide polymorphism on the HTR2A gene, resulting in altered serotonin 2A (5-HT2A) receptor function ( Table 1 ). While there is a lack of clinical studies with the 5-HT2A receptor and cannabis, research has demonstrated that the CB1R is expressed on serotonin neurons; therefore, the binding of THC to this receptor increases neuronal firing [32]. In pre-clinical studies, the CB1R and 5-HT2A have been shown to form a heteromer that could be responsible for altered homeostasis of the serotonin system [33]. This type of serotonin receptor is commonly found in the prefrontal cortex and evidence has suggested that alterations in receptor function have demonstrated association with mood disorders and psychosis [25]. Several studies have proven that cannabinoids affect the serotonergic system; however, the data regarding the relationship between cannabis and HTR2A and its subsequent effects are limited [25].

The PGx test results identified the patient as a CYP2D6 intermediate metabolizer, which is heavily involved in the metabolism of several opioid drugs utilized for pain (e.g., codeine, tramadol, hydrocodone, oxycodone) [34]. Guidelines are available for CYP2D6 and select opioids, which state that individuals with CYP2D6 intermediate metabolizer status may experience altered effects (e.g., possible adverse drug events, increased risk for pharmacotherapy failure) when compared to CYP2D6 normal metabolizers [34]. Given this patient’s genetic results, guidelines, and current pain status, the clinical pharmacist suggested morphine as an alternative, as it does not utilize CYP2D6 for metabolism [34]. Studies have been conducted evaluating pain sensitivity in individuals with COMT genotype Val/Met and Met/Met, reporting that those with this polymorphism have an increased pain sensitivity [35]. In addition, low COMT activity has demonstrated association with increased opioid analgesia and opioid side effects (e.g., nausea, vomiting) [35]. Considering these studies and the patient’s COMT genotype, if an opioid were to be prescribed, starting a low dose opioid and monitoring for any medication-related side effects would be suggested. There are additional genetic polymorphisms proven to affect an individual’s reaction to THC, such as the Taq1A polymorphism in the dopamine receptor gene; however, these data were not available for the patient at the time of these interventions. [7].

See also  CBD Oil And Drug Tests Pa

4. Conclusions

Cannabis use has been demonstrated to have an impact on dopamine concentrations in the brain, resulting in side effects like hallucinations. In a condition like PD, many interactions and their subsequent side effects can occur when combining cannabis with dopamine-promoting drugs and the genetic variants that affect dopamine. This patient case demonstrates the importance of considering cannabis use when evaluating for potential drug–drug and drug–gene interactions in an individual’s regimen. Considering all drug-use (e.g., prescribed, recreational, over-the-counter drugs), along with an individual’s PGx results when evaluating a patient allows for a safer and more accurate approach when completing comprehensive assessments.


The authors want to thank Katie Meyer for her assistance. The authors would also like to thank Pamela Dow and Dana Filippoli, for their comprehensive review and comments on this manuscript.

Author Contributions

Conceptualization, N.D.T.-P., D.T., A.M. and V.M.; writing—original draft preparation, K.P., N.D.T.-P. and D.T.; writing—review and editing, K.P., N.D.T.-P., D.T., A.H., V.M. and J.T.; supervision, D.T., A.M., N.A., V.M. and J.T. All authors have read and agreed to the published version of the manuscript.


This research received no external funding.

Institutional Review Board Statement

Informed Consent Statement

Informed consent was obtained from all subjects involved in the study.

Data Availability Statement

Conflicts of Interest

The authors declare no conflict of interest.


Publisher’s Note: MDPI stays neutral with regard to jurisdictional claims in published maps and institutional affiliations.


1. Banerjee S., McCormack S. Medical Cannabis for the Treatment of Chronic Pain: A Review of Clinical Effectiveness and Guidelines. Canada Agency Drugs Technology Health; Ottawa, ON, Canada: 2019. [(accessed on 25 June 2021)]. Available online: https://www.ncbi.nlm.nih.gov/books/NBK546424/pdf/Bookshelf_NBK546424.pdf [Google Scholar]

2. Methaneethorn J., Poomsaidorn C., Naosang K., Kaewworasut P., Lohitnavy M. A delta-9-tetrahydrocannabinol physiologically-based pharmacokinetic model development in humans. Eur. J. Drug Metab. Pharm. 2020; 45 :495–511. doi: 10.1007/s13318-020-00617-5. [PubMed] [CrossRef] [Google Scholar]

3. Wang G.S., Bourne D.W.A., Klawitter J., Sempio C., Chapman K., Knupp K., Wempe M.F., Borgelt L., Christians U., Heard K., et al. Disposition of oral delta-9 tetrahydrocannabinol (THC) in children receiving cannabis extracts for epilepsy. Clin. Toxicol. 2019; 58 :124–128. doi: 10.1080/15563650.2019.1616093. [PubMed] [CrossRef] [Google Scholar]

4. Klumpers L.E., Thacker D.L. A brief background on cannabis: From plant to medical indications. J. AOAC Int. 2019; 102 :412–420. doi: 10.5740/jaoacint.18-0208. [PubMed] [CrossRef] [Google Scholar]

5. Bloomfield M.A.P., Ashok A.H., Volkow N.D. The effects of delta-9-tetrahydrocannabinol on the dopamine system. Nature. 2016; 539 :369–377. doi: 10.1038/nature20153. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

6. Klein M.O., Battagello D.S., Cardoso A.R., Hauser D.N., Bittencourt J.C., Correa R.G. Dopamine: Functions, signaling, and association with neurological diseases. Cell Mol. Neurobiol. 2019; 39 :31–59. doi: 10.1007/s10571-018-0632-3. [PubMed] [CrossRef] [Google Scholar]

7. Sarangi S.C., Sopory P., Reeta K.H. Chronic neurological disorders: Genetic and epigenetic markers for monitoring of pharmacotherapy. Neuro India. 2021; 69 :252–259. doi: 10.4103/0028-3886.314522. [PubMed] [CrossRef] [Google Scholar]

8. Parkinson’s Foundation. [(accessed on 21 June 2021)]. Available online: https://www.parkinson.org/

9. Koonrungsesomboon N., Khatsri R., Wongchompoo P., Teekachunhatean S. The impact of genetic polymorphisms on CYP1A2 activity in humans: A systemic review and meta-analysis. Pharm. J. 2018; 18 :760–768. doi: 10.1038/s41397-017-0011-3. [PubMed] [CrossRef] [Google Scholar]

10. Klein K., Zanger U.M. Pharmacogenomics of cytochrome P450 3A4: Recent progress toward the “missing heritability” problem. Front Genet. 2013; 4 :12. doi: 10.3389/fgene.2013.00012. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

12. Cravanas B., Frei K. The effects of cannabis on hallucinations in Parkinson’s disease patients. J. Neurol. Sci. 2020; 419 :117206. doi: 10.1016/j.jns.2020.117206. [PubMed] [CrossRef] [Google Scholar]

13. Grotenhermen F. Pharmacokinetics and pharmacodynamics of cannabinoids. Clin. Pharmacokinet. 2003; 42 :32–360. doi: 10.2165/00003088-200342040-00003. [PubMed] [CrossRef] [Google Scholar]

14. Mlost J., Bryk M., Starowicz K. Cannabidiol for Pain Treatment: Focus on Pharmacology and Mechanism of Action. Int. J. Mol. Sci. 2020; 21 :8870. doi: 10.3390/ijms21228870. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

15. Bland T.M., Haining R.L., Tracy T.S., Callery P.S. CYP2C-catalyzed delta9-tetrahydrocannabinol metabolism: Kinetics, pharmacogenetics and interaction with phenytoin. Biochem. Pharmacol. 2005; 70 :1096–1103. doi: 10.1016/j.bcp.2005.07.007. [PubMed] [CrossRef] [Google Scholar]

16. Jiang R., Yamaori S., Takeda S., Yamamoto I., Watanabe K. Identification of cytochrome P450 enzymes responsible for metabolism of cannabidiol by human liver microsomes. Life Sci. 2011; 89 :165–170. doi: 10.1016/j.lfs.2011.05.018. [PubMed] [CrossRef] [Google Scholar]

17. Deodhar M., Al Rihani S., Arwood M., Darakjian L., Dow P., Turgeon J., Michaud V. Mechanisms of CYP450 inhibition: Understanding drug-drug interactions due to mechanism-based inhibition in clinical practice. Pharmaceutics. 2020; 12 :846. doi: 10.3390/pharmaceutics12090846. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

18. Sienkiewicz-Oleszkiewicz B., Wiela-Hojeńska A. CYP2C19 polymorphism in relation to the pharmacotherapy optimization of commonly used drugs. Pharmazie. 2018; 73 :619–624. [PubMed] [Google Scholar]

19. Whiting P.F., Wolff R.F., Deshpande S., Di Nisio M., Duffy S., Hernandez A.V., Keurentjes J.C., Lang S., Misso K., Ryder S., et al. Cannabinoids for medical use: A systematic review and meta-analysis. JAMA. 2015; 313 :2456–2473. doi: 10.1001/jama.2015.6358. [PubMed] [CrossRef] [Google Scholar]

20. Kraft B., Frickey N.A., Kaufmann R.M., Reif M., Frey R., Gustorff B., Kress H.G. Lack of analgesia by oral standardized cannabis extract on acute inflammatory pain and hyperalgesia in volunteers. Anesthesiology. 2008; 109 :101–110. doi: 10.1097/ALN.0b013e31817881e1. [PubMed] [CrossRef] [Google Scholar]

21. Hill K.P. Medical marijuana for treatment of chronic pain and other medical and psychiatric problems: A clinical review. JAMA. 2015; 313 :2474–2483. doi: 10.1001/jama.2015.6199. [PubMed] [CrossRef] [Google Scholar]

22. Schmack K., Bosc M., Ott T., Sturgill J.F., Kepecs A. Striatal dopamine mediates hallucination-like perception in mice. Science. 2021; 372 doi: 10.1126/science.abf4740. [PubMed] [CrossRef] [Google Scholar]

23. Oh Y.S., Kim J.S., Lee P.H. Effect of rivastigmine on behavioral and psychiatric symptoms of Parkinson’s disease dementia. J. Mov. Disord. 2015; 8 :98–102. doi: 10.14802/jmd.15041. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

24. Ko J.H., Antonelli F., Monchi O., Ray N., Rusjan P., Houle S., Lang A., Christopher L., Strafella A.P. Prefrontal dopaminergic receptor abnormalities and executive functions in Parkinson’s disease. Hum. Brain Mapp. 2013; 34 :1591–1604. doi: 10.1002/hbm.22006. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

25. Cohen K., Weizman A., Weinstein A. Modulatory effects of cannabinoids on brain neurotransmission. Eur. J. Neurosci. 2019; 50 :2322–2345. doi: 10.1111/ejn.14407. [PubMed] [CrossRef] [Google Scholar]

26. Zou S., Kumar U. Cannabinoid receptors and the endocannabinoid system: Signaling and function in the central nervous system. Int. J. Mol. Sci. 2018; 19 :833. doi: 10.3390/ijms19030833. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

27. Hindley G., Beck K., Borgan F., Ginestet C.E., McCutcheon R., Kleinloog D., Ganesh S., Radhakrishnan R., D’Souza D.C., Howes O.D. Psychiatric symptoms caused by cannabis constituents: A systematic review and meta-analysis. Lancet Psychiatry. 2020; 7 :344–353. doi: 10.1016/S2215-0366(20)30074-2. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

28. Henquet C., Rosa A., Delespaul P., Papiol S., Faňanás L., Van Os J., Myin-Germeys I. COMT Val158Met moderation of cannabis-induced psychosis: A momentary assessment study of ‘switching on’ hallucinations in the flow of daily life. Acta Psychiatr. Scand. 2009; 119 :156–160. doi: 10.1111/j.1600-0447.2008.01265.x. [PubMed] [CrossRef] [Google Scholar]

29. Chen J., Lipska B.K., Halim N., Ma Q.D., Matsumoto M., Melhem S., Kolachana B.S., Hyde T.M., Herman M.M., Apud J., et al. Functional analysis of genetic variation in catechol-O-methyltransferase (COMT): Effects on mRNA, protein, and enzyme activity in postmortem human brain. Am. J. Hum. Genet. 2004; 75 :807–821. doi: 10.1086/425589. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

30. Akil M., Kolachana B.S., Rothmond D.A., Hyde T.M., Weinberger D.R., Kleinman J.E. Catechol-O-methyltransferase genotype and dopamine regulation in the human brain. J. Neurosci. 2003; 23 :2008–2013. doi: 10.1523/JNEUROSCI.23-06-02008.2003. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

31. Narayanan N.S., Rodnitzky R.L., Uc E. Prefrontal dopamine signaling and cognitive symptoms of Parkinson’s disease. Rev. Neurosci. 2013; 24 doi: 10.1515/revneuro-2013-0004. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

32. Lau T., Schloss P. The cannabinoid CB1 receptor is expressed on serotonergic and dopaminergic neurons. Eur. J. Pharmacol. 2008; 578 :137–141. doi: 10.1016/j.ejphar.2007.09.022. [PubMed] [CrossRef] [Google Scholar]

33. Viñals X., Moreno E., Lanfumey L., Cordomí A., Pastor A., de La Torre R. Cognitive impairment induced by delta9-tetrahydrocannabinol occurs through heteromers between cannabinoid CB1 and serotonin 5-HT2A receptors. PLoS Biol. 2015; 13 :e1002194. doi: 10.1371/journal.pbio.1002194. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

34. Crews K.R., Monte A.A., Huddart R., Caudle K.E., Kharasch E.D., Gaedigk A., Dunnenberger H.M., Leeder J.S., Callaghan J.T., Samer C.F., et al. Clinical Pharmacogenetics Implementation Consortium guideline for CYP2D6, OPRM1, and COMT genotypes and select opioid therapy. Clin. Pharm. Ther. 2020; 110 :888–896. doi: 10.1002/cpt.2149. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

35. Jensen K.B., Lonsdorf T.B., Schalling M., Kosek E., Ingvar M. Increased sensitivity to thermal pain following a single opiate dose is influenced by the COMT Val158Met polymorphism. PLoS ONE. 2009; 4 :e6016. doi: 10.1371/journal.pone.0006016. [PMC free article] [PubMed] [CrossRef] [Google Scholar]

Articles from Medicina are provided here courtesy of Multidisciplinary Digital Publishing Institute (MDPI)

How useful was this post?

Click on a star to rate it!

Average rating 3 / 5. Vote count: 1

No votes so far! Be the first to rate this post.