Marijuana use and psychosis

Statistics show that more than half of the population in our province has used cannabis at least once – that’s 1.84 million people in BC alone and it is more widespread here than in the rest of Canada.

Further, 65 percent of people found it very easy to access marijuana in BC.

This is likely no surprise to you if you are one of the many who has tried cannabis or who uses it regularly. Certainly, it doesn’t seem to be difficult to access since most teenagers can find it readily and we hear of so many grow ops even in our own city.

Studies have also found that over the past three decades since cannabis use has been popular its potency has increased from one and a half percent THC to almost four and a half percent.

Over the same time period there has been a sharp decline in the age of onset of cannabis use and an increase in the rates of regular users. These statistics together mean that the amount of THC consumed and the duration of such consumption have increased dramatically in recent years among adolescent users.

In the midst of the higher use and dosage of the drug, I find that many people in my practice who use cannabis regularly feel as though this drug use is clinically insignificant. Unfortunately, in spite of this popular perception about marijuana, there is growing scientific evidence to the contrary.

Studies show that cannabis users report more psychotic symptoms and have higher rates of diagnosed psychosis than individuals who have not used cannabis. Further, the risk of psychosis and psychotic symptoms increases with the frequency of use and is greater if individuals begin using cannabis at an earlier age.

Individuals who may be more susceptible – for example, those with a personal or family history or psychotic symptoms appear to be more likely to develop psychotic symptoms if they use cannabis.

These findings persist in studies even after controlling for a range of variables such as personal characteristics, other types of drug use and a family history of psychiatric disorder.

In fact, evidence from six longitudinal studies in five countries shows that regular cannabis use predicts an increased risk of schizophrenia diagnosis or of reporting psychotic symptoms.

These relationships do not seem to be the result of using cannabis to self-medicate for already-present psychotic symptoms. What is more plausible is that cannabis use precipitates schizophrenia in individuals who are vulnerable. Studies have also found that the drug is not helpful to individuals with bipolar disorder or attention deficit disorder.

The last time we did a column on the risks of cannabis use we received more response than for any other column, much of it very opinionated and aggressive.

Most of the mail we received was from international lobby groups for the legalization or further popularization of cannabis who seem to scan the media for all stories that might harm their case and then aggressively try to silence critics.

I find it odd that the same people who are often very critical of the pharmaceutical industry and demanding of exacting standards when it comes to the testing of new drugs will at the same time champion the use of such a powerful, psychoactive substance. A substance that is produced without regulation or quality control, distributed without any information about possible risks, side-effects, drug interactions or contraindications and without the benefit of controlled clinical trials either to prove the benefits or document the risks.

What the growing evidence is showing is the need for further research to truly find any associated benefits to cannabis use as well as to document potential risks so that individuals can actually make an informed decision as to whether they want to put this substance in their bodies.


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