Author: James Anderson

Study Suggests Marijuana Use Damages Brain Immune Cells Vital to Adolescent Development

Around 38% of full time college students and 41% of non-full time college students, who are aged 19–22 used cannabis at least once in one year (Schulenberg et al., 2018; Marijuana use among US college students remains at highest level in three decades, 2018). This data clearly indicates the widespread use of cannabis among youth and it is the high time to elucidate the consequence of cannabis use in human. Although the direct effect of cannabis exposure and health consequences is still unknown, numerous case reports, population-based studies as well as animal studies demonstrated the potential link between cannabis use and neurovascular as well as neurological diseases. Unfortunately, both cerebrovascular and neurological disorders are found to be higher in young population as they are the main consumer. Exogenous cannabinoids such as CBD and nabilone are also found to have therapeutic activity in psychiatric disorders including schizophrenia, posttraumatic stress disorder (PTSD) and general and social anxiety (Cohen et al., 2019).

A 2013 reply to the New Zealand study suggests that personality factors may play a role in both marijuana use and cognitive decline. The connection between weed and Alzheimer’s disease is complicated, especially since they both can affect part of the brain responsible for memory. Before using cannabis to treat Alzheimer’s it’s important to untangle this complex relationship. Although you cannot overdose on cannabis, using too much cannabis can be unpleasant at any age. Older adults using cannabis should be aware that cannabis may affect them differently.22 Tell your physician if you experience unusual dizziness or lightheadedness, and be alert to your fall risk.

On the other hand, CB2 receptors are located in peripheral nervous system and immune system and the primary function of this receptor is anti-inflammatory activity through initiating an immune response to reduce inflammation as well as tissue damage (Turcotte et al., 2016). Also, it plays a pivotal role in the immune suppressive action of the cannabinoids (Sharma et al., 2012) (see also Figure 2). Note that CB1 receptor are primarily located in the brain and spinal cord and to a much lesser extent there are also present in the gastrointestinal tract, reproductive organs as well as muscles and vascular system. CB2 receptors are primary located in spleen, skin, and bones as well as the immune cells.

What Neurotransmitter Does Weed Affect?

Especially for newbies, starting with a low dose and gradually increasing it is best.20 Don’t use more until you know how the dose affects you. You need to understand how your body reacts to cannabis to minimize your risk of adverse effects. “Our understanding of the effects of marijuana on the brain is imperfect, and human research in this area is a work in progress,” said Dr. Fernando D. Testai, neurologist and professor at the University of Illinois at Chicago, in a news release.

1. To the best of our knowledge, a very few studies have been performed to understand the mechanism of detrimental effect of cannabis on both neurology and the BBB.
2. Despite having serious effects of marijuana in human health, its use has been legalized in Canada and different states of USA.
3. The Canadian Parliament passed Bill C-45, the Cannabis Act to legalize and regulate the production, distribution, and consumption of cannabis on June 19, 2018, and its legalization started effective from October 17, 2018 (Crepault, 2018).
4. From these studies we can conclude that among the 107 neurovascular cases, almost 84% were ischemic stroke related to cannabis or cannabinoid use (both natural and synthetic).

To test their idea, researchers used genetically engineered mice with a mutation that mimics a genetic risk for psychiatric disorders in humans, along with normal mice as a comparison group. The mice carrying the mutation show changes to the brain with or without THC, specifically to the areas responsible for emotion, learning and memory. More research needs to be done to fully understand the effects of marijuana on the brain of persistent cannabis users. Some studies link marijuana to cognitive decline, particularly in adolescents.

What should you do if you experience cognitive effects of cannabis?

Ultimately, this leads to an inhibition of N and P/Q type calcium currents and an activation of A type, inwardly rectifying potassium currents and mitogen activated protein kinase (Sierra et al., 2015) (see Figure 3). Kamiya cautions that study results from genetically engineered mice cannot be applied directly to what happens in a human brain. But “studies in animals suggest there may be long lasting and negative effects of marijuana use during adolescence,” Kamiya says. Some studies have also linked marijuana use to declines in IQ, especially when use starts in adolescence and leads to persistent cannabis use disorder into adulthood. Post-stroke inflammatory responses can be reduced by CB2 ligands whereas, activation of CB1 receptors promotes chemical hypothermia. Both processes result in a reduced stroke infarct volume (Leker et al., 2003; Murikinati et al., 2010).

Sarafian et al. have previously shown that marijuana cigarettes promote the formation of ROS while lowering the intracellular levels of glutathione (Sarafian et al., 1999). In addition, other investigators found that THC, the main psychoactive component in the cannabis, acts as a potent promoter of OS and inflammation, thus appearing as a risk factor for the onset of ischemic stroke (Wolff et al., 2015b). On the other hand, there are also evidences that non-psychoactive CBDs, can have neuroprotective effects by reducing the reactivity of microglial cells, and transmigration of leukocytes (through downregulation of chemokines, interleukin-1, and vascular cell adhesion molecule-1) (Mecha et al., 2013). In vitro studies using amyloid-beta-stimulate PC12 neurons CBD could inhibit the activity of inducible nitric oxide synthase, thus preventing the production of nitric oxide and reducing OS (Esposito et al., 2006). By contrast, in vivo studies to assess the protective effect of cannabis treatment against OS development and nigrostriatal cell injury induced by intrastriatal injection of rotenone did not produce any significant result (Omar, 2015).

However, the occurrence of neurovascular complication among middle aged and older people was significantly lower compared to the young and adult population with a value of 5.6% (aged between 51–60 years) and 2.80% (aged between 61–70 years). This data clearly indicates that, young people are severely affected by neurovascular diseases as they consume cannabis in higher amount compared to older people. Although some studies have been able to establish the possible correlation between cannabis use and ischemic stroke occurrence, only 11% of total reports have demonstrated the incident of hemorrhagic stroke due to cannabis exposure (Fonseca and Ferro, 2013; Wolff and Jouanjus, 2017). Moreover, compilation of these case reports indicates that along with cannabis or cannabinoids use, other risk factors like alcohol, tobacco, dyslipidemia, migraine without aura, hypertension etc. also act as prodromal factors for the onset of cerebrovascular diseases.

Study Suggests Marijuana Use Damages Brain Immune Cells Vital to Adolescent Development

Specifically, activation of CB1 receptor activation reduces glutamate release (Hayakawa et al., 2007), allied excitotoxicity (Shen et al., 1996) and increased cerebral blood flow (Parmentier-Batteur et al., 2002). On the other hand, CB2 receptors activation results in reduced pro-inflammatory cytokines release, neutrophil recruitment (Murikinati et al., 2010; Zarruk et al., 2012) and adhesion of leukocyte to cerebral vessels (Zhang et al., 2007). The psychoactive agent of cannabis, THC binds with the cannabinoid 1 (CB1) receptor in the brain and the non-psychoactive component, CBD is the most likely to interact with cannabinoid 2 (CB2) receptor and exert their activities. Therefore, cannabis is used in medical purposes to reduce inflammation, relieve pain, and decrease seizures (Rivera-Olmos and Parra-Bernal, 2016; Perucca, 2017). THC is absorbed and reaches high blood concentration rapidly after inhalation through lungs (Vandevenne et al., 2000).

Positive and Negatives: Long-Term Effects of Weed

The unchecked OS leads then to mitochondrial depolarization, lipid peroxidation, DNA fragmentation and inflammation which at the cerebrovascular level can cause BBB damage and ultimately facilitate the onset of CNS diseases. Interestingly, it can also be noted from these case reports that the occurrence of neurovascular diseases such as stroke has drastically increased after 2010. Widespread availability of cannabis or synthetic cannabinoids and its legalization across the world may be the underlying reasons behind this.