Marijuana and psychosis

This was in today’s Economist newsletter, and I’ve seen it elsewhere too.  Scary!  But then again, what is the definition of psychosis?

Isn’t getting your thought and emotions so impaired that you lose contact with external reality the point of high THC content marijuana?  Is this a feature not a bug?  External reality can be rough.

The study, in The Lancet, used the ICD-10 Criteria (F20-33), so schizophrenia and manic/bipolar episodes. The study compared people hospitalized for that kind of thing versus a control general population. Here’s how the study worked:

We included patients aged 18–64 years who presented to psychiatric services in 11 sites across Europe and Brazil with first-episode psychosis and recruited controls representative of the local populations.

Then this part:

We applied adjusted logistic regression models to the data to estimate which patterns of cannabis use carried the highest odds for psychotic disorder. Using Europe-wide and national data on the expected concentration of Δ⁹-tetrahydrocannabinol (THC) in the different types of cannabis available across the sites, we divided the types of cannabis used by participants into two categories: low potency (THC <10%) and high potency (THC ≥10%). Assuming causality, we calculated the population attributable fractions (PAFs) for the patterns of cannabis use associated with the highest odds of psychosis and the correlation between such patterns and the incidence rates for psychotic disorder across the study sites.

“expected” and “assuming” are two words that do a lot of work here, but I don’t have time to read the whole study, I have to write cartoons.

In my neighborhood the most booming new shops sell either marijuana or cold brew coffee.  Personally I wonder if drinking huge amounts of highly caffeinated cold brew might be more crazy-making than marijuana.

There is certainly ample psychosis in Los Angeles, so much so that it might be necessary to induce mild psychosis just so you can understand what’s going on with everybody.  The chicken and egg, correlation and causation on psychosis / drug use is a tough one to unravel, as the study’s authors acknowledge.  The study also notes that patients presenting with psychosis were more likely to have smoked ten or more cigarettes a day.