Tetrahydrocannabinol (THC) is one of the two primary cannabinoids found in cannabis.
You’re probably familiar with THC, as it is the cannabinoid responsible for the psychoactive euphoric-inducing high that cannabis users experience. THC can be consumed through the inhalation of smoke or vapour and is also available in the form of tinctures, edibles and oils.
Human beings have been consuming cannabis for thousands of years, but it wasn’t until 1964 that THC’s chemical structure was isolated and understood.
THC has the same molecular structure as cannabidiol (CBD) – 21 carbon atoms, 2 oxygen atoms, and 30 hydrogen atoms. Despite CBD and THC having similar chemical structures, subtle differences in the arrangement of atoms in THC and CBD result in profoundly different physiological effects on users, such as the psychoactive effects caused by THC.
In this article, we’re going to cover the basics of THC, how it works in the brain and what research is showing about THC’s potential medicinal benefits and safety profile.
How Does THC Work?
When consumed, THC induces its psychoactive effects by binding to cannabinoid 1 (CB1) receptors in the body. This binding induces chemical responses that lead to feelings of euphoria.
The effects that THC will have on a person is highly dependant on dose, one’s tolerance to THC, as well as other factors such as the ratio of THC to CBD, terpenes, and other cannabinoids, which all influence the effects of cannabis in what is known as the ‘entourage effect’.
THC’s chemical structure is similar to a chemical called anandamide, a brain lipid which causes the brain to ‘see’ THC and induce short-term alterations to cognitive function. Once THC is consumed, it affects regions of the brain responsible for pleasure, concentration, coordination, sensory and time perception.
The Way THC Is Consumed Matters
The method by which THC is consumed is very important in determining the strength of a THC high, how long the onset takes and how many hours the effects last.
For example, consuming THC through inhalation (via smoke or vapour) causes near-immediate effects, as THC is able to cross the blood-brain barrier rapidly. Orally consuming cannabis through an edible can take 30-45 minutes for the effects of THC to be felt, as it takes time for THC to make its way through the digestive system and into the bloodstream. THC consumed through edibles also causes stronger psychoactive effects due to the way that THC is metabolized when orally consumed.
Both smoking and eating cannabis provide the body with THC, but according to research, when THC is consumed orally, a higher proportion of Delta-9-THC makes its way to the liver. Delta-9-THC turns into 11-hydroxy-THC in the liver, which is a stronger psychoactive compound, and is produced in a higher proportion through edibles in comparison to smoking and vaping.
The Medical Benefits Of THC
While THC’s reputation may be largely built on its psychoactive effects, there is also a growing body of research indicating that THC has significant therapeutic properties. THC is used to treat conditions such as pain, glaucoma, insomnia, low appetite (and anorexia), nausea, anxiety, among other conditions. THC is even available in New Zealand through prescription in the form of the medicine Sativex. Sativex is a mouth spray containing both THC and CBD. Sativex is used as an add-on treatment for patients with Multiple Sclerosis suffering from spasticity.
THC May Help Ease Chronic Pain
Supporters of legal THC often tout its ability to ease chronic pain as one of its most significant therapeutic effects. Aside from anecdotal evidence, there is research to indicate that THC may act on pain systems.
One study published in Behavioural Pharmacology in 2012 explored how THC helps manage pain caused by cancer via the activation of CB1 and CB2 receptors. Interestingly, the researchers found that the activation of these receptors due to THC caused an analgesic (pain-relieving) effect comparable to morphine.
THC Can Curb Nausea & Vomiting
Research is showing is that THC may also act as an antiemetic, meaning it helps to curb nausea and vomiting. THC’s antiemetic effects occur thanks to its interaction with the 5-hydroxytryptamine 3 (5hHT3) receptor. The 5HT3 receptor has demonstrated an ability to increase GABA release. GABA is a neurotransmitter important for health, but in excess can cause vomiting.
CB1 and 5-HT3 receptors are both located on gamma-aminobutyric acid (GABA neurons) and thus may have an opposing effect on GABA release, resulting in less nausea. It is thought that THC’s activation of CB1 receptors may neutralize nausea caused by a 5-HT3-mediated GABA increase.
THC Promotes Sleepiness
Drowsiness is a stereotypical trait of cannabis consumers and it seems that THC may also be responsible for this. THC’s potential sedative effects can be extremely helpful for patients suffering from insomnia and other sleep disorders. Low doses of THC (15mg) have been shown to have a sedative effect, which leads to an increase in sleep activity.
THC Increases Appetite
Colloquially known as the “munchies”, THC increases appetite, which may be good for those suffering from a decreased appetite due to diseases such as cancer or conditions such as anorexia and other eating disorders.
Researchers believe this increase in appetite happens thanks to THC’s interaction with CB1 receptors. CB1 receptors can be found in the lateral hypothalamus region of the brain, and their activation causes interactions with dopaminergic neurons which play a key role in the regulation of food reward.
THC May Reduce Tumor Growth (At Least In Animals)
Some preliminary studies show that THC may also reduce tumour growth, at least in animal models. Animal studies have shown that activating cannabinoid receptors can impair cancer cell development. This is exciting, but it’s important to keep in mind that research on cannabis and cancer is very much in its infancy, and there is a lot more research that needs to be done before we can make claims about the effectiveness of THC for treating cancer.
THC could be regarded as an effective treatment for cancer, but not necessarily because it directly inhibits tumour growth. THC seems to be helpful for easing the symptoms of cancer treatment such as pain and nausea, without causing other adverse effects that many other prescription medications cause.