How Medical Marijuana Works on the Brain to Reduce Pain

Medical marijuana is becoming increasingly popular as a means of treating pain in patients with chronic conditions. Living with pain can be incredibly detrimental to a patient’s quality of life and thus they might opt to try a course of medical marijuana, even though we don’t fully understand the long-term impacts of using the substance and even though it may have a few short-term side effects like dizziness and memory impairment.

But if you are going to consider using medical marijuana as an option, then it’s important to first understand how it impacts the brain and what precisely it does to trigger its effects. Read on then and we will take a closer look at what medical marijuana actually does to your neurochemistry and how this helps to treat pain.

A Bit About the Brain

Before we go any further in explaining the actions of marijuana, it is first important to discuss how the brain works and how marijuana might impact on those functions.

Fundamentally, the brain is comprised of a ‘network’ of neurons (brain cells) that form during our development as well as when we create new memories. When these neurons fire, they have a range of different effects, many of which result in subjective experiences. For instance, we have neurons that correspond with every ‘pixel’ in our vision and each time one of those fires it results in our perception of a spot of light in that position. Likewise, we have neurons that represent parts of the body, etc.

While our neurons are connected in a web-like structure, no neurons are actually in physical contact with any others and as a result any signals that fire need to send a transmission across a small gap called a ‘synapse’. When this happens, a short electrical signal fires across that gap alongside a series of chemicals called ‘neurotransmitters’ which give the signal some emotional intent – making it seem more important, more positive or negative to us subjectively.

At the end of every neuron are sacks called ‘neuro-vesicles’ that are able to release neurotransmitters, as well as receptors that are able to receive them. Specific receptors however will only be able to receive their corresponding neurotransmitters (it is not a ‘one size fits all’ scenario…). Furthermore, neurons in different regions of the brain have different specific receptors and so are more sensitive to specific neurotransmitters. Confused yet?

How Marijuana Works

With that in mind, we can now take a look at precisely how marijuana actually works. Specifically, marijuana has its effect because of a substance called ‘THC’ or ‘Tetrahydrocannabinol’. This is a substance that is able to plug the ‘cannabinoid receptors’, specific receptors that receive cannabinoid neurotransmitters.

By plugging these neurotransmitters, this excites those neurons but at the same time prevents the natural cannabinoid receptors produced by the brain from having their usual effect. In other words, those areas of the brain that are full of cannabinoid receptors become at once excited and activated, but also unable to communicate and operate normally.

The areas of the brain that contain high densities of cannabinoid receptors include the hypothalamus, the hippocampus, the amygdala, the cerebellum, the basal ganglia, the neocortex and the brain stem. More generally, they exist in the parts of the brain that are related to motivation, to memory, to drive and to reward.

Thus, when you use marijuana, your reward and motivation areas light up and you get a sense of euphoria as the brain releases more reward neurotransmitters. At the same time though, you lose your ability to differentiate between what’s important and what isn’t and your ability to form new memories becomes impaired as your short-term memory gets damaged. You’ll also find that you feel relaxed (due to the lack of directed motivation) and that you are more easily distracted. Because the hippocampus is affected, you’ll also find that your appetite is affected and this is why recreational users experience what they call ‘the munchies’.

A Bit About Pain

When you experience pain, this starts when a ‘nociceptor’ in your body is excited. This is the technical term for a ‘pain receptor’ and only parts of the body with a density of nociceptors are actually capable of experiencing pain. Open brain surgery amazingly can’t be felt by patients because the brain doesn’t have its own nociceptors!

But while it’s the nociceptors that tell us we’re in pain, it’s the brain that creates that actual feeling of pain and so it is essentially a psychological phenomenon. If you have ever experienced severe pain but then had friends over to socialize, you may have found that you could actually be ‘distracted’ from your feeling of pain to the point where you maybe even forget you had the discomfort in the first place.

Bringing it All Together

While marijuana has many profound effects on the brain, it does not appear to impact on any of the areas that are actually involved with the regulation or sensation of pain. So why is it increasingly being used as an analgesic?

The answer appears to lie in the psychological component of pain. Specifically, because pain requires focus and attention in order to take on its full effect, it’s very possible to simply distract a patient from their experience of it and thereby lessen its effects.

According to one study published in the Journal Pain (1), this may be precisely how marijuana exerts its effects. Essentially, the sensation of pain is still the same, but users find it more tolerable because their systems relating to focus, attention and memory are muted.

On top of this, the release of various reward hormones might also have an indirect analgesic effect as they themselves can suppress feelings of pain (another reason that socializing can help to reduce feelings of discomfort).

Recently, more and more research has also been looking at the role of marijuana on the immune system and regulating inflammation. The cannabinoid receptors CB1 and CB2 are both found on the immune cells which suggests an important role in the immune system and possibly inflammation (2). As it is inflammation that often triggers the firing of the nociceptors, this might be another mechanism through which marijuana combats pain. Marijuana also contains other cannabinoids such as cannabidiol (CBD) which appears to have more physical effect on the immune system and less psychological impact making it perhaps the preferred active compound for use of cannabis as a pain treatment for those concerned about psychological side effects.

Other Therapeutic Effects of Marijuana

That said, some people will consider the psychological impacts of marijuana to be a positive. As mentioned, they can help to distract patients from the pain, but furthermore they might also be useful for treating some of the anxiety that comes from a chronic condition. Those suffering from potentially terminal cancer for instance might well benefit from being able to use marijuana in order to reduce their feelings of anxiety or fear associated with the condition and many would consider this a very favorable therapeutic benefit.

The fact that marijuana impacts appetite can also be used to therapeutic effect and thus marijuana is sometimes prescribed as a treatment for those with HIV suffering reduced appetite and weight loss, as well as for those with eating disorders such as anorexia and bulimia.

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