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Mental Health
Cannabis and psychosis
Dr. Zerrin Atakan, FRCPsych
National Psychosis Unit, UK
What chemicals are there in an average cannabis plant?
Cannabis is a complex plant containing over 400 chemical elements and 60 compounds. Two of the major compounds are tetrahydrocannabinol (delta-9-THC) and cannabidiol (CBD). THC is the psychoactive ingredient, which produces the stoned' effect. There has been growing evidence that it can also precipitate psychosis in vulnerable individuals, as well as trigger a relapse of symptoms among patients who already have a psychotic illness, such as schizophrenia or bipolar disorder.
THC or CBD?
The amount of ingredients vary greatly according to the plant. For instance some hydroponically grown cannabis (i.e. skunk) is known to have very high levels of THC, but very low levels of CBD. CBD is devoid of the typical psychological effects associated with THC, but it has a strong anti-anxiety effect. In other words, CBD can relax people and make them feel calm. It is also thought to have an anti-psychotic effect in psychotic patients. THC, on the other hand, can bring on psychotic symptoms such as paranoia, delusions and hearing or seeing things. It can also worsen existing symptoms. One of the reasons why people or patients with psychosis carry on using cannabis may be to achieve relief of tension via the anti-anxiety effect of CBD. However, THC component of cannabis will increase the risk of exacerbation of psychotic symptoms. When someone is smoking cannabis, they would not know how much of it is THC or CBD, but it is more than likely that they would be smoking high THC, low CBD cannabis. The strength of cannabis is defined according to its THC content and this is thought to have increased threefolds since 1960's.
When we smoke cannabis where does it go in our body?
We have a cannabinoid receptor system in our brain, spinal cord, heart, spleen and some other organs. This system has interconnections with other systems, especially in the brain and is thought to have a significant role in our survival. When cannabis is smoked, THC binds to the cannabinoid receptors, instead of our natural body chemical which allows the system to function normally and this leads to some other receptors systems to release their chemicals such as dopamine. Dopamine is known to have a role in the genesis of psychotic symptoms or experiences. So, smoking cannabis temporarily prevents this system to carry out its normal function, as well as effecting other systems.
Can we be dependent on cannabis?
Previously, it was thought that cannabis use did not cause dependence, tolerance or withdrawal symptoms, but more recent scientific evidence disproves these views.
Is there a link between regular cannabis use and developing a mental illness?
The use of cannabis has been increasing steeply in many countries, and the age of initial use has been decreasing. With relaxation of the law and wide availability of the drug in many countries, cannabis use is becoming more common than cigarette smoking, especially with the growing disapproval of tobacco use among young people. The association between cannabis use in young people and subsequent risk of developing a psychotic illness has significant implications. There is growing research evidence that early and regular cannabis smoking can lead to the development of a psychotic illness such as schizophrenia or bipolar disorder in those who are genetically vulnerable. Furthermore, there is also an increased risk of developing depression and anxiety disorder.
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