What is THC? What are the different types of THC?
Tetrahydrocannabinol (THC) is a well-known cannabinoid found in cannabis plants, recognized for its psychoactive effects. There are different forms of THC, each with its own unique properties and effects.
Delta-9-THC is the most common form of THC found in cannabis plants and is typically the compound referred to when discussing THC. It's the primary psychoactive ingredient in cannabis, responsible for the "high" sensation associated with the illegal use of cannabis. [1, 2].
Delta-8-THC and Delta-10-THC are other forms of THC found in cannabis plants, albeit in trace amounts. These cannabinoids have similar chemical structures to Delta-9-THC, but their effects can be slightly different. They are less potent than Delta-9-THC, but still have psychoactive properties [2].
Difference in the effects of Delta-9-THC, Delta-8-THC and Delta-10-THC
In humans, Delta-9-THC can cause a range of effects which differ from those for Delta-8-THC and Delta-10-THC.. These include altered perception of time and events, giddiness, increased focus, and relaxation. However, it can also lead to side effects such as anxiety, difficulty thinking and speaking, dry mouth, increased appetite, memory loss, rapid heart rate, red eyes, and slowed reaction times [3].
Delta-8-THC has been reported to produce a variety of impacts on users. A study from 2022 found that most Delta-8-THC users experienced a great deal of relaxation (71%), euphoria (68%), and pain relief (55%). Cognitive distortions such as difficulty concentrating (81%), difficulties with short-term memory (80%), and altered sense of time (74%) were also reported.
As for Delta-10-THC, there is currently a lack of research into its affects and risks [2].
Variations in THC Content in plants
The THC content in cannabis plants can vary significantly, influenced by factors such as the plant's genetic makeup and environmental conditions. For instance, the THC content in drug-type cannabis plants grown in Sicily and Tuscany ranged from 0.82% to 1.31% [4].
Different cannabis varieties, or chemovars, can also have varying THC contents. For example, Type I chemovars are high in THC, while Type III chemovars are high in CBD (cannabidiol), another cannabinoid with therapeutic effects but without the psychoactive properties of THC [5].
How does THC compared to CBD
Cannabidiol (CBD) is the other primary cannabinoid found in the cannabis plant. THC and CBD share the same molecular structure, with 21 carbon atoms, 30 hydrogen atoms, and 2 oxygen atoms. However, the arrangement of these atoms differs, leading to distinct effects on the body [6].
THC is known for its psychoactive properties, which can cause a "high" sensation. It achieves this by activating cannabinoid type 1 receptors in the brain [7]. On the other hand, CBD is a CB1 antagonist, meaning it can block the intoxicating impact caused by these receptors. In fact, taking CBD with THC may inhibit the effects of THC [7]. In terms of cognitive function, studies have shown that THC can impair memory in a dose-dependent manner, whereas CBD does not seem to have this effect [8]. Importantly, CBD can be used legally within the UK for relaxation or therapeutic reasons, whereas THC consumed from cannabis is not legal within the UK.
Risks of taking THC
The risks of taking THC are wide ranging including adverse drug events, adverse effects on your lungs and psychological impacts. While it has been used illegally for millennia, the medical use of THC has increased in recent years, exposing more individuals to its potential risks. These risks can be amplified by drug-drug interactions, especially in individuals with complex medical conditions and co-prescribed medications [9].
One of the most common physical risks associated with THC use is the potential for adverse drug events when combined with other medications. THC is metabolised by enzymes CYP3A4 and CYP2C9, which can be impacted by several common medications. This can lead to increased bioavailability of THC, especially in certain racial groups where CYP2C9 polymorphisms are prevalent [9].
THC can also have broad interactions with drug-metabolizing enzymes and can enhance the adverse effects of other medications. These pharmacodynamic interactions include neurological effects, impact on the cardiovascular system, and risk of infection [1].
Smoking cannabis, which contains THC, can lead to lung irritation, chronic cough, increased phlegm production, and an increased risk of lung infections and lung cancer [6].
THC can also have significant psychological effects. High levels of THC can increase the risk of a harmful reaction. Regular use of high doses can increase the risk of addiction [6].
THC can also cause temporary side effects such as increased heart rate, decreased blood pressure, dry mouth, coordination problems, slower reaction times, short-term memory loss, panic, paranoia, and hallucinations. Some research suggests a potential link between high-THC marijuana and long-term mental health effects, including psychosis, especially in regular users and young people [6].
Risks of taking CBD
CBD, or cannabidiol, is a non-psychoactive component of cannabis and typically has less risks than THC. It's typically well-tolerated, even in large doses. However, CBD may cause side effects like weight changes, nausea, and diarrhoea. It's also important to note that any side effects of CBD are likely the result of drug-to-drug interactions between CBD and other medications you may be taking. In some cases, this may include liver damage [6].
Summary different types of THC and comparison to CBD
THC and CBD are two primary active compounds found in cannabis, known as cannabinoids [7]. They both have an impact on cannabinoid type 1 receptors in the brain, but their effects differ significantly [7]. THC is associated with anxiety, dysphoria, positive psychotic symptoms, physical and mental sedation, and subjective intoxication. Importantly, it is also illegal to consume in the UK. In contrast, CBD has proven to be safe and well-tolerated, with no significant symptomatic or physiological effects [9]. The different forms of THC vary in their effects, however Delta-9-THC, Delta-8-THC are the most researched, with Delta-9-THC being the most commonly associated with the psychoactive effects of cannabis.