Yes, smoking pot can trigger psychosis. But, no, smoking a few joints is not the equivalent of a “get out of jail free” card.
That’s what we should retain from the case of Mark Phillips, who received a light sentence in an assault case after the court accepted the argument that the 37-year-old was suffering from “marijuana-induced psychosis.”
The case has caused much consternation, for a couple of reasons. The assault itself was horrible: On Dec. 7, in St. Thomas, Ont., Mr. Phillips attacked a family of immigrants in a parking lot because they were speaking Spanish, breaking one man’s ribs with a baseball bat while yelling that he was a terrorist. The incident was filmed and posted on YouTube.
He pleaded guilty to assault causing harm (after originally being charged with aggravated assault) and received a conditional discharge, meaning that after serving three years’ probation, doing 240 hours of community service and refraining from consuming all non-prescription drugs during the probation period, he will not have a criminal record.
The sentence has miffed many. The case leaves the impression that a well-to-do white man (Mr. Phillips is a Toronto lawyer) has been treated with kid gloves by the courts. His defence – that his seemingly racist attack was caused by consumption of marijuana – has also been widely mocked.
Let’s leave the arguments about race – and income – and status-based double-standards in the justice system to others and focus on the medical aspect of the case – namely: Can cannabis cause psychosis?
That question is hotly debated in scientific circles and the answer seems to be a mitigated yes.
First, we need to understand what psychosis is – a mental disorder in which thought and emotions are so impaired that contact is lost with external reality. (It is not the same as hallucinations.)
Psychosis is quite rare – fewer than three in 100 people will experience a psychotic episode in their lifetime. People who smoke or otherwise consume cannabis, especially in significant quantities, have a higher incidence.
But correlation is not the same as causation.
Some people have vulnerability, a genetic predisposition to psychosis, and cannabis can be a trigger, as can other things like trauma or amphetamines. Severe mental illness like schizophrenia tends to arise in late teens and early adulthood, the same time young people tend to experiment with drugs, so the psychosis can be coincidental. Finally, many people with severe mental illnesses that feature psychotic episodes self-medicate, with cigarettes, alcohol and cannabis.
In other words, it’s a classic chicken-and-egg scenario: It’s not clear which comes first, mental illness or cannabis use.