Cannabis use and psychosis

What is psychosis?

Psychosis refers to a state of mind in which one s interpretation or experience of reality is distorted. It is a syndrome that consists of the following symptoms: delusions (false beliefs), hallucinations (perceiving objects or events that are not physically present), disorganised thought, and unusual speech and behaviours. Psychosis is seen in various different conditions such as schizophrenia, brief psychotic disorder, bipolar disorder, and major depression. It can also result from the effects of illicit drugs and some physical illnesses.

Psychosis occurs more commonly in young adults. It is estimated that around 2% of people will experience a psychotic episode in their lifetime, of which 80% will experience their first episode between the ages of 15-30. Most people recover from a psychotic episode with treatment. The time required for recovery varies from person to person.

Does using cannabis cause psychosis?

Evidence suggests that heavy cannabis use in adolescence is associated with a higher risk of developing a psychotic disorder later on, such as schizophrenia. Using cannabis in adolescence is also associated with experiencing a greater number of psychotic symptoms in adulthood, even after controlling for pre-existing symptoms. A review of studies has shown that regular cannabis use is associated with twice the risk of psychotic symptoms or psychotic disorders compared with non-users. It is also associated with a younger onset of psychotic illness. Cannabis use carries an even greater risk of psychotic symptoms and disorders for those with susceptibility to psychosis (i.e. individuals who are already experiencing psychosis-like symptoms) or who carry a genetic predisposition.

If you have a psychotic disorder, does using cannabis affect treatment outcomes?

People who continue to use cannabis following the onset of psychotic illness have been shown to experience poorer treatment outcomes, including poorer medication compliance, a greater number of symptoms, and impaired social functioning. Even after controlling for medication adherence, patients who continue to use cannabis have a higher number of symptoms five years later compared to patients who did not use cannabis or who stopped using it after the onset of psychosis.

For help with issues relating to cannabis and health, please call the National Cannabis Information and Helpline on 1800 30 40 50.

For further help with mental health issues:

Lifeline 13 11 14

Headspace www.headspace.org.au
mindhealthconnect www.mindhealthconnect.org.au

- November 2013