Cannabis induced psychosis is a common argument against reform from prohibitionists. Studies linking cannabis use with psychosis and other mental health issues are often cited as a reason adults shouldn’t be allowed access to the drug, but despite a huge increase in cannabis consumption, mental health diagnosis numbers remain relatively stable.
While a number of studies have shown that there are links between psychosis and cannabis, there are usually other factors at play. While the causality of cannabis use and psychosis is yet to be proven, there is still a correlation, and for a small number of people, cannabis can prevent a mental health risk. Could CBD mitigate this risk, and would a minimum CBD level in cannabis products negate the arguments of prohibitionists?
What is psychosis, and why do studies link it to cannabis?
Psychosis is a condition that influences the way your brain processes information. It causes a loss of contact with reality, the three main symptoms being hallucinations, delusions and confused and disturbed thoughts. Hallucinations are where someone sees, hears, smells, tastes or feels things that don’t exist outside of their mind. Delusions are where a person has “an unshakeable belief in something untrue”. When someone is experiencing symptoms of psychosis it is often referred to as having a “psychotic experience” or “psychotic episode”. Whilst psychosis can be caused by mental (psychological) conditions such as bipolar disorder or schizophrenia, psychotic episodes can also be brought on by alcohol or drug misuse.
The ‘misuse’ element here is crucial. Studies have suggested that yes, there is a correlation between regular cannabis use and psychosis – and that using cannabis can increase the risk of later developing a psychotic illness, including schizophrenia. (This risk is of course amplified in people with existing mental health problems). However, it is important to note that these kinds of conclusions often refer to the more ‘powerful strains’ of cannabis, namely street cannabis or skunk, which contain levels of the active ingredient THC above 10%. We know that cannabis contains around 100 different cannabinoid compounds and that the psychotomimetic effects of ingesting cannabis are induced by THC. In the UK, where recreational cannabis remains illegal and medicinal cannabis is in its infancy, skunk has been blamed for London having the highest rates of psychosis in Europe. However, when mitigated for most healthy adults, the risks of psychosis are minimal.
How CBD can prevent cannabis psychosis
While CBD was formerly thought to lack pharmacological effects, in recent years, CT scans have allowed doctors and clinicians to make startling discoveries in regards to its benefits. Namely, that CBD may help people with psychotic disorders by dampening down abnormal brain activity that arises in such patients, and also help to lower the risk of psychosis in individuals using cannabis. ‘Brain imaging’ suggests that just a single dose of CBD can reduce symptoms of psychosis by ‘resetting’ activity in three brain areas.
The brain imaging study that took place in 2018 used 33 participants with psychotic symptoms along with a control group of healthy participants, to test the effects of CBD on psychosis. Half the psychosis group was given oral doses of CBD, whilst the other half were given a placebo. The control group wasn’t given anything but their brain scans were used to compare with those suffering from psychotic symptoms. The volunteers’ brains were studied as they performed simple tasks in a magnetic resonance imaging machine. As to be expected, scans showed abnormal activity in the brains of those with symptoms compared with the healthy control group, but astonishingly, participants who had taken the CBD capsule showed less extreme abnormalities than those who had the placebo.
Senior author on the study back in 2018, Professor Sagnik Bhattacharyya, from the Institute of Psychiatry, Psychology & Neuroscience, King’s College London said: “Our study provides important insight into which areas of the brain CBD targets. It is the first time research has scanned the brains of people with a diagnosis of psychosis who have taken CBD and, although the sample is small, the results are compelling in that they demonstrate that CBD influences those very areas of the brain that have been shown to have unusual activity in people with psychosis.”
Dr Bhattacharyya and his colleagues are now launching the first large-scale, multi-centre trial to investigate whether cannabidiol can be used to treat young people at high risk of developing psychosis. The trial is supported by a £1.85 million grant from an NIHR and MRC partnership.
The results of the 2018 study have renewed interest in CBD as an alternative to current antipsychotic medicines as it could a) prove more tolerable and b) be more effective for a subset of people who do not respond to other more traditional antipsychotics.
So, whilst THC has been linked to an increased risk for psychosis, CBD is potentially beneficial for symptoms of psychosis. Therefore, if we are to protect legal cannabis consumers, perhaps a minimum limit of CBD in cannabis products, as suggested in the Green Party manifesto, would go some way to reducing the risk of vulnerable consumers developing psychotic symptoms.
How CBD can be used in the future to prevent risks of psychosis
Given that CBD appears to be a buffer against the potentially psychotic effects of THC on the brain, it is important to consider how CBD can be used in the future to prevent risks of psychosis. According to Dr Bhattacharyya, “there is an urgent need for safe treatment for young people at risk of psychosis…one of the main advantages of cannabidiol is that it is safe and seems to be very well tolerated, making it in some ways an ideal treatment.”
With accumulating evidence that the endocannabinoid system and CBD can positively impact symptoms of psychosis, there are ways of using CBD to fend off the risk of psychosis.
Now, we know that cannabis use can increase the risk of onset and subsequent outcome of psychosis, but these often catastrophic effects are particularly evident in people who use high potency skunk-like cannabis which has high levels of THC and low levels of CBD. For those using cannabis and hash with lower levels of THC and higher levels of CBD, the risks of psychosis are minute. As CBD not only has opposing effects to THC but has been shown to block some of its negative (and particularly psychotomimetic) effects, CBD has been indicated as a treatment to be used prior to the onset of psychosis in patients who are at clinical high risk for the disorder.
So, if you’re someone who consumes skunk or high THC weed, it is a sensible idea to try and supplement your intake with CBD. Try ingesting weed with a higher level of CBD, take some CBD oil or even add some CBD flower to your usual joint.

















