How medical cannabis works

When people hear about medical cannabis, many picture something far removed from conventional medicine. In practice, the treatment rests on a relatively recent scientific discovery: our body has its own system that interacts with the substances in the plant. Understanding this system helps answer questions, ease fears and set realistic expectations.

The endocannabinoid system

In the early 1990s, researchers identified a network of receptors and molecules in the human body that came to be known as the endocannabinoid system. It is present in the brain, the spinal cord, the peripheral nerves, the immune system, the gut and many other tissues.

Its main job is to help the body keep its balance, which doctors call homeostasis. It plays a part in regulating processes such as:

• pain perception;
• sleep and rest cycles;
• mood and the response to stress;
• appetite and bowel function;
• inflammation and the immune response;
• memory and learning.

The three main pieces

Put simply, the endocannabinoid system works like a messaging network with three parts:

• Endocannabinoids: molecules the body makes itself, such as anandamide and 2-AG. They are produced on demand, whenever the body needs them.
• Receptors: the “locks” these molecules fit into. The best known are CB1, abundant in the nervous system, and CB2, more closely linked to immune cells and inflammation.
• Enzymes: they break down the endocannabinoids once their job is done, ending the message.

Where the plant's cannabinoids come in

Cannabis sativa produces more than a hundred compounds called phytocannabinoids. The most studied are CBD (cannabidiol) and THC (tetrahydrocannabinol), which interact with the endocannabinoid system in different ways:

• THC binds directly to the CB1 and CB2 receptors, much like the body's own endocannabinoids;
• CBD acts in a broader, more indirect way: it modulates receptors, influences other systems (such as the serotonin system) and affects how endocannabinoids are broken down.

The plant also contains other cannabinoids in smaller amounts, as well as aromatic compounds called terpenes, which are also being studied.

Why responses vary so much

Everyone's endocannabinoid system has its own characteristics. The number of receptors, how quickly the body processes substances, other medications and the person's overall health all influence the result. That's why two people with the same diagnosis may need different doses and formulations.

It's also why treatment usually starts with a low dose that is increased gradually, a process called titration, until the best balance between benefits and side effects is found.

What science already knows, and what is still being studied

For some conditions, such as certain forms of treatment-resistant epilepsy, there are solid clinical trials and medicines approved by regulatory agencies. For others, such as chronic pain and spasticity in multiple sclerosis, the evidence is moderate. And for some conditions, such as insomnia and anxiety, the results are still preliminary.

Knowing these levels of evidence is part of honest care: medical cannabis may help, but it isn't right for everyone and it doesn't replace treatments that already work.

Medical cannabis is neither a magic solution nor a taboo. It is a therapeutic tool that calls for careful assessment, sound judgment and follow-up.

In summary

• The body has an endocannabinoid system that helps regulate pain, sleep, mood, appetite and inflammation.
• CBD and THC interact with this system in different ways.
• Treatment uses products with a known dose, prescribed and adjusted gradually.
• Whether treatment is appropriate is always an individual decision, based on a careful medical assessment.