By Luke Sumpter

We’re just slowly beginning to understand some of the complex mechanisms at work when we consume cannabis. No question, weed is affecting our brain in some way, but how exactly does this happen? This question is of particular interest to medical cannabis patients, especially concerning whether or not cannabis impacts brain chemistry. Could cannabis actually be harmful in the long term, or do its therapeutic benefits extend beyond the immediate satisfaction of smoking or consuming it? Let’s look at how cannabis affects the brain by breaking down some of the latest research in this area.

The way cannabis affects the brain

Located all throughout the human body and brain are so-called cannabinoid receptors, which are part of the entire endocannabinoid system. The endocannabinoid system is involved in a variety of physiological processes, including appetite stimulation, pain-sensation, mood, and memory.

What makes cannabis special is that it produces compounds that act in a similar way as the compounds the body creates naturally. Like endocannabinoids found internally, the cannabinoids in the cannabis plant bind and interact with receptors.

THC, the main psychoactive cannabinoid binds to receptors in the brain, creating psychoactive effects that influence perception. One difference between endocannabinoids and THC is that the latter lasts longer.

The natural endocannabinoids, in comparison, are broken down fairly quickly by proteins. Although similar in function, THC does not exactly fit into receptors like its endogenous siblings. This may perhaps explain some of the intensity behind consuming psychoactive cannabis.

The effects of cannabis on the brain go beyond merely making us stoned, relaxed, or giggly as a result of consumption. The reason for this is that cannabinoid receptors are located in the central nervous system, which controls many functions of our body and mind.

These include mood, memory, pleasure, pain, fear, and motor function - just to name a few. Moreover, these receptors are found all throughout our body, meaning that potentially every part of us can be affected by consuming cannabis.

Cannabinoid Receptor Sites

The therapeutic potential of cannabis

With the endocannabinoid system playing such a central role, researchers are now looking into the therapeutic potential of cannabis.

Some researchers see the function of the endocannabinoid system as mediating a healthy balance between the mind and the body. The active compounds in weed, such as THC and CBD are thought of as being highly influential in terms of regulating this natural homeostasis. 

Some researchers are postulating that an imbalance or deficiency in the endocannabinoid system could be at the root of various health conditions like nausea and the increased likelihood for seizures.

Evidence is also mounting that imbalances in the endocannabinoid system are linked to several mood and mental health disorders. These conditions include bipolar disorder and PTSD, but also physical ailments such as IBS, migraines, muscle spasms, and fibromyalgia.

These findings on the effects of cannabinoids published in a landmark 2003 study by Ethan B. Russo[1] have been confirmed time and time again in subsequent research.

Yet another significant study performed by British researchers found that the compounds in cannabis have a therapeutic effect when treating anxiety and psychotic stress in patients suffering from schizophrenia.

What does weed actually do to the brain?

We know that the cannabinoids in weed can engage with our brain directly by binding to cannabinoid receptors, but what does cannabis really do to the brain? Can it possibly cause long-term changes in brain chemistry or function?

Myths about the dangers of consuming cannabis are still making the rounds today, so let’s look at the latest findings there as well.

Cannabis and brain health

Cannabis has been demonised for almost a century now. All sorts of claims have been made about the plant’s supposed “terrible” side effects - in particular its mental repercussions. Recent studies are now debunking most of these claims.

One major study in 2015 took on the claim about the potential for abnormal changes in the brain from long-term weed consumption. The researchers examined brain morphology of cannabis consumers and compared it to those of non-consumers using MRI technology. The results showed that there was no statistical difference between the two groups. In short, there is no evidence to support that chronic cannabis use leads to any type of brain abnormality.

Related studies are now also debunking the myth of prolonged cannabis use and the alleged declining cognitive abilities therein. In-keeping with the above, researchers have found no evidence that consuming the plant leads to a lower IQ. This is yet another myth that has been around for a long time that classically portrays stoners as lazy and not especially bright.

Weed Affect Brain

Does cannabis have any negative effects on health?

One of the main concerns with cannabis is that it may be habit-forming. The real question here is whether such a dependence negatively impacts one’s health.

First, one would have to first consider whether dependency is actually a relevant issue among cannabis consumers. Estimates suggest that the percentage of those individuals who have developed a dependence on weed is much smaller as compared to tobacco and alcohol consumers. While approximately 9% of cannabis consumers have formed a dependence, the rates of alcohol and tobacco dependence are much higher at around 15 and 30%, respectively.

There is no question that cannabis is deemed as “attractive” to those who use it. Studies do indeed confirm that it stimulates the reward centre in the brain of long-term users. Whether this appeal could lead to some dependence-related issues requires more conclusive research.

Are there positive effects of cannabis on the brain?

There are ongoing efforts in many countries to legalize, or at least decriminalize the use of weed. Research is now being performed on a broader scale, with findings that are not only debunking most negative myths about cannabis, but also uncovering many potentially therapeutic effects.

More public figures and politicians are beginning to advocate for the herb by trying to sway governing bodies to update or change laws. In the past, advocates may have kept it simple by pointing out that cannabis, from a medicinal perspective, is safer than many available foods. Today, science allows us greater insight into the many potential benefits of cannabis on the human brain and body.

Increasingly, more mainstream medical experts are now facing a reality where cannabis is indeed showing a plethora of positive health effects, from its anti-inflammatory and antioxidant properties to the promotion of new cell growth in the brain.

Quite in contrast to the old tale of how consuming weed may possibly bring on brain damage, it is now believed that it can in fact improve brain health, at least in certain circumstances. Among the most active areas in cannabis research today include the plant’s potential to treat illnesses such as Alzheimer’s and Parkinson’s Disease.

How does THC affect behaviour?
Brain Structure Regulates THC Effect
Amygdala Emotions, fear and anxiety Panic and paranoia
Basal Ganglia Starting a movement Slowed reaction time
Brain Stem Information between brain and spinal column Antinausea effects
Hippocampus Learning new information Impaired memory
Neocortex Complex thinking, feeling and movement Altered thinking, judgment and sensation
Nucleus Accumbens Motivation and reward Euphoria
Spinal Cord Transmission of information between body and brain Altered pain sensitivity
Brain Parts

🧬 Cannabis may reverse (some) effects of aging

While research is ongoing about whether using cannabis for brain-related health conditions is effective, some equally exciting news comes from researchers who believe that cannabis can help reverse some of the effects of aging, at least where cognitive abilities are concerned.

The renowned journal Nature Medicine published these findings from a study conducted in Germany[2] at the University of Bonn with colleagues at the Hebrew University in Jerusalem. According to this latest research, THC may possibly keep our brain from slowing down as we age.

The study examined the effect of THC on two groups of mice. The test involved rigorous examinations of mice of different ages, which the researchers introduced to a daily regimen of THC. To assess the performance of the mice, the scientists tested their ability to navigate various mazes to see how well they could recognise familiar objects.

The young mice “under the influence” pretty much behaved as one would expect from stoned teenagers, with lower test scores after consuming cannabis. The old mice, on the other hand, greatly improved in their abilities after receiving THC. In fact, their skill levels were shown to be as strong as those of the (sober) younger mice.

The researchers noted a profound, long-lasting improvement in cognitive performance in the older mice using low doses of THC. Since the endocannabinoid system in mice is not much different in function than in humans, the team is now planning to expand these studies with a clinical trial later this year, focussing on “aged” brains.

When it comes to the effects of aging and how this impacts the brain, here too the endocannabinoid system will likely play an important role. With cannabis’ supposed ability to restore the endocannabinoid system’s natural balance, it may well be that it can also be the key to prevent dementia.

Cannabis and our brain - An optimistic outllok

Among the most fascinating findings in the area of modern cannabis research is the plant’s ability to promote cell growth in the brain. Should preliminary research (which has until now only been conducted using animal models or small sample sizes) confirm these findings, this would open up many new therapeutic opportunities. Treating health conditions like Alzheimer’s and Parkinson’s Disease may seem lightyears away, but it just may be a reality in the near future.

External Resources:
  1. Mapping the brain: scientists define 180 distinct regions, but what now? - Queensland Brain Institute - University of Queensland
  2. Foreword - Discovering the Brain - NCBI Bookshelf
  3. Cannabis, alcohol and cigarette use during the acute post-concussion period - PubMed
  4. Understanding the endocannabinoid system as a modulator of the trigeminal pain response to concussion - PMC
  5. Cannabinoid Receptor Signaling in Central Regulation of Feeding Behavior: A Mini-Review - PMC
  6. Efficacy of medicinal cannabis for appetite-related symptoms in people with cancer: A systematic review - PubMed
  7. Cannabidiol Reduces the Anxiety Induced by Simulated Public Speaking in Treatment-Naïve Social Phobia Patients - PMC
  8. Effects of cannabidiol (CBD) on regional cerebral blood flow - PubMed
  9. CKS is only available in the UK | NICE
  10. The role of the endocannabinoid system in pain - PubMed
  11. Cannabis and Pain: A Clinical Review - PMC
  13. Interaction of Cannabis Use and Aging: From Molecule to Mind - PMC
  14. Cannabinoids remove plaque-forming Alzheimer’s proteins from brain cells - Salk Institute for Biological Studies
  15. Pros and Cons of Marijuana in Treatment of Parkinson’s Disease - PMC
  16. Frontiers | Are CB2 Receptors a New Target for Schizophrenia Treatment?
  17. Cannabidiol enhances anandamide signaling and alleviates psychotic symptoms of schizophrenia - PMC
  18. Cannabidiol modulates serotonergic transmission and reverses both allodynia and anxiety-like behavior in a model of neuropathic pain - PMC
  19. Why Marijuana Displeases | National Institute on Drug Abuse (NIDA)
  20. Addiction | Health Effects | Marijuana | CDC
  21. The Association Between Cannabis Use and Schizophrenia: Causative or Curative? A Systematic Review - PMC
  22. What are marijuana's long-term effects on the brain? | National Institute on Drug Abuse (NIDA)
This content is for educational purposes only. The information provided is derived from research gathered from external sources.

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