The cannabis plant is made up of numerous chemical compounds, those unique to the plant are called cannabinoids. Delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are the two cannabinoids of most interest. Cannabinoids affect the user by interacting with specific receptors within the brain. The effects experienced depend on the levels of THC and CBD and the areas of the brain in which the cannabinoids interact. Mood, motivation, memory, cognition, perception, and psychomotor performance are most affected as they have the most receptors for cannabinoids.
In recent years research has revealed THC and CBD have opposite actions on the brain and body. This factsheet highlights the main differences between these two cannabinoids.
The main difference between these two cannabinoids is the extent to which they are psychoactive or mind altering .
Essentially, THC is known to have strong psychoactive properties it is THC which gives the high feeling and the reason most people use cannabis. CBD on the other hand, is believed to have an anti-psychoactive effect which appears to moderate the high and some of the other negative effects experienced with THC, particularly on anxiety and psychosis.
Cannabis is known to provoke feelings of anxiety and paranoia in some people, especially when used in high doses or by inexperienced users. This effect can be attributed to THC. CBD has been shown to alleviate the anxiety caused by THC, and may even reduce anxiety when administered on its own. Indeed, a number of studies have demonstrated CBD can reduce social anxiety and general discomfort during public speaking performances and other anxiety-provoking situations.
Evidence suggests a link between the use of cannabis and the onset and exacerbation of psychosis, and again it seems THC is responsible for triggering these adverse symptoms. CBD appears to have anti-psychotic properties, meaning this cannabinoid may be protective against the psychosis-like effects of THC. As a result, CBD is currently being investigated as an antipsychotic treatment for patients with schizophrenia.
Memory and cognition
THC has been shown to have acute and long-term adverse effects on the parts of the brain that are important for learning and memory. A growing body of research has indicated CBD may be neuro-protective, reducing the cognitive and memory impairments caused by THC. Studies have reported that cannabis with the same levels of THC but different amounts of CBD present cause varying degrees of short-term impairment.
One of the most commonly reported reasons for using cannabis is it assists with better quality sleep, and indeed sleepiness or drowsiness is often a reported side-effect of cannabis. While existing research on the role of cannabis on sleep is unclear, some suggest it is THC which has this drowsy effect, and in contrast, CBD facilitates a state of wakefulness .
Pain, inflammation and nausea
THC and CBD have both been shown to help with some kinds of pain relief, but CBD is believed to have more anti-inflammatory properties. CBD (possibly in interaction with THC) is also said to suppress muscle spasms and reduce nausea.In light of this, CBD has been receiving increasing attention for its potential medicinal value.
There is also some evidence that CBD may have an anticonvulsant effect (including reductions in seizure frequency and/or severity). However, such evidence is gained primarily through studies with animal models (in rats and mice). Other than some anecdotal reports, little reliable clinical evidence of this effect in humans is available although such studies are currently underway.
What does this all mean?
Cannabis is a very complex drug. The opposing effects of the two main cannabinoids, THC and CBD, may explain why people sometimes experience different effects when using different strains or types of cannabis. The level of THC vs. CBD (potency) in cannabis is greatly variable, but these days cannabis plants have generally been bred to have high THC levels and low (to no) CBD. This increasingly common form of high-THC/low-CBD cannabis is thought to be responsible for the reported rise in cannabis use disorders, links to mental health conditions, and cognitive impairments seen among users. With this in mind, and with a lack of evidence to-date to support use for some illnesses, it is crucial patients seek professional medical advice as opposed to self-medicating with cannabis.