The facts. Information about mental illness. |

Further information on cannabis and mental health

It is well known that one of the possible results of taking cannabis is to experience psychosis. However, there is some evidence that taking cannabis can have more long term effects on someone's mental health.

The impact of cannabis use

Hallucinations and Delusions written in smoke

People who use cannabis are 40% more likely to experience psychosis than people who do not use cannabis.

The more you smoke the more the risk will increase.

The younger you smoke, the greater the risk. Experts believe that this is because cannabis can affect the development of your brain.

Psychosis can happen to anyone but a family history of severe mental illness makes you more vulnerable.

Psychosis

About one person in 25 will experience at least one psychotic episode at some point in their life.

When you’re psychotic you lose touch with reality. This may involve terrifying hallucinations and delusions. You usually won’t realise that what’s happening to you isn’t real - no matter how much someone tries to tell you otherwise.

For those where psychosis is caused by drugs, symptoms may go away quickly. But for some, initial psychosis will develop into a long term severe mental illness such as schizophrenia.

How can cannabis lead to psychosis?

Cannabis has loads of active ingredients, but it’s what’s known as delta-9-tetrahydrocannabinol (THC) that gets you high. It does this by binding with “receptors” in your brain. Receptors are parts of the brain that link cells so that they can “talk” to each other about our thoughts and actions. THC binds with receptors in the same part of the brain as the dopamine system. Dopamine is a chemical that sends messages about how we think, feel and behave. Psychotic symptoms are thought to be caused by too much dopamine in the brain.

Cannabis makes psychosis worse

Smoking cannabis can make existing psychosis worse. Its calming effects can reduce fear and anxiety in the short term, but it can cause relapse and increase the risk of developing uncontrollable muscle spasms and twitches. Because cannabis also contains mind altering chemicals it can reduce the effectiveness of antipsychotic medication.