We have already gone over this subject at length in a previous post. However, I am starting to change my mind on the subject after a lot of reading. It is looking more and more like heavy cannabis consumption during the teenage years is somehow implicated in the development of schizophrenia later on.
How this works is not known. Cannabis is probably not causing it directly, otherwise we should see epidemics of schizophrenia. More likely it is triggering it in a person who is already vulnerable. But the evidence has been flooding from, now from 30 different studies. And the younger the person is when they start and the more they use in the teen years, the greater the risk of schizophrenia later on. Some studies are even finding a dose-response relationship.
The fatal flaw in this theory has been that the rate of schizophrenia has not risen during since the start of the cannabis epidemic. I used cannabis for many years myself, and I known thousands of users, many of them long-term and heavy users. Other than making some young people lazy and somewhat paranoid, I haven’t seen a lot of ill effects from the drug.
I knew one guy who had schizophrenia who loved pot, but it made him a lot worse, so everyone tried to keep it away from him.
I’ve known only one marijuana user out of the many thousands of drug users that I have known who developed schizophrenia, but he was a heavy speed user for 10-20 years. He developed schizophrenia around age 37 after using methamphetamine heavily for 10-20 years. I am pretty sure that over a decade of heavy speed use caused his schizophrenia since heavy meth use causes massive damage to the brain.
I’ve never known any other cases, and I never saw any cases the whole time I was growing up. I hung out with heavy users, sold the drug myself for many years, and never saw any psychosis, not even a temporary case. However, the pot around nowadays is extremely strong and the age at first use has been dropping. I tried some recently and can testify that it is extremely strong indeed. I can handle it fine as I can easily handle just about any drug out there, but I can see how it could flip someone.
Quite a few of the local young people around here smoke pot. I’ve gotten to know quite a few of them and learned of their heavy marijuana use. They ranged in age from 16-23. A couple of them were dealers in their 20’s who were using large quantities of this very strong pot.
I knew about the pot-schizophrenia link and I kept looking for it in all of these individuals. I have yet to see a case of psychosis, much less schizophrenia, among these young people. I saw one person who got paranoid on pot, and I saw other cases of the “lazy pothead” syndrome, but in general, they were quite healthy mentally and led full and enriched lives. If cannabis is implicated in schizophrenia, it sure doesn’t cause it very often, as most even heavy users seem to avoid this drastic consequence.
Many kids are using this extremely strong pot at younger and younger ages, often daily for many years in adolescence. The pot we were using was much weaker, most of us did not use it every day, and most of us didn’t start using until around age 16 or so. Heavy use started around age 20 or so.
While cannabis in general does not appear to cause significant structural damage in adults, some very ominous findings are coming out about use in adolescence.
A recent study found that adults who started using cannabis before age 17 (16 or younger) had smaller brains overall, had less grey matter (fewer brain cells) yet more white matter (connections between neurons) (Earleywine 2005). Less neurons yet more connections isn’t exactly brain damage. Instead it’s just a brain that appears to have developed in a different way.
But this is the problem. The brain is still developing during adolescence. If cannabis impairs and changes normal brain development, this could be a bad thing. As it stands, no one should use cannabis before age 17 due to the risk of permanent brain changes of unknown significance. Delaying use until after age 16 apparently results in avoidance of these changes.
Even the most pot-critical researchers are claiming that cannabis is only causing 8-13% of schizophrenia cases. However, they can’t even prove that. Those are just models, and those models are not yet backed up with statistical data, which continues to show the schizophrenia rate as flat.
This interview was quite interesting. This psychiatrist posits that cannabis is causing schizophrenia, but only in people who use it, usually on a daily basis, for years starting in adolescence. The risk is greatest the younger you start. Delaying use until 19 or 20 results in dramatically lowered risk. The risk apparently drops to zero if one waits until age 21 to start using cannabis. In other words, I, at age 52, could smoke a ton of dope between now and the time I die and it won’t give me schizophrenia no matter how much I use.
At the very least, it’s certain that early and heavy cannabis use brings schizophrenia on sooner than it would have occurred ordinarily. However, that means years of life lost to psychosis that are gone forever. Many schizophrenics who use cannabis find that they have a worse course, as the cannabis triggers new psychotic episodes.
Yet schizophrenics seem to love the stuff, paradoxically. That’s probably because at first it seems to calm them down. Schizophrenia is a horrible illness, and sufferers will take just about anything to escape from the symptoms.
One theory that keeps coming is that is quite common in the early stages of schizophrenia (the prodromal phase) for users to turn to various drugs to relieve their distress. Schizophrenics often go years before their first diagnosis.
This article by Robin Murray, a notorious proponent of the cannabis-schizophrenia link, describes a case of supposed cannabis-induced schizophrenia in a teenager. At age 15, he became a heavy cannabis user at age 17, probably to treat his symptoms. A few years later, at age 20, he was finally diagnosed. Halfway through his prodromal symptoms, he began using cannabis to treat his illness.
I had a good friend recently who was a paranoid schizophrenic. He was 28 at the time and had apparently had the illness since he was 20 or so. He had not yet been diagnosed.
Hence the cannabis-schizophrenia link is said to be merely kids in the prodromal phase seeking relief for a condition that they are going to develop soon anyway and cannabis is not implicated in the disorder. This is always possible, but new research is suggesting that this is not the case.
With the new research, it is looking more and more like teenagers need to stay away from cannabis period. If they wish to use it, they should wait until age 19-20 or even better yet, age 21 when all cannabis-schizophrenia risk is gone.
- Earleywine, Mitch. 2002. Understanding Marijuana: A New Look at the Scientific Evidence (pp. 149-150). New York: Oxford University Press.