My wife called my attention to an editorial page piece in the July 2, 2013 edition of The Wall Street Journal linking marijuana use to schizophrenia. I at first wondered who the paper had chosen as a distinguished medical figure to write on his or her research study of the association between use of this drug and the most severe mental illness, but read the commentary and realized it was written, not by a professor, but by a Yale psychiatry resident in training.

Having been a Duke resident more than 45 years ago, I was aware that young physicians at major teaching centers might, as I did, see a particular spectrum of the general patient population, in many cases the most ill portion of it.  Therefore I was less than certain of the strength of the basis for his viewpoint, but felt it was a highly significant topic and it was well worth perusing the literature pro and con.

Does this cause mental illness?

In 2010 Time magazine published a well-balanced article titled "The Link between Marijuana and Schizophrenia." That led me to several medical research reports, but the lay press article itself was interesting.

It commented that studies showed those who were diagnosed with schizophrenia were approximately twice as likely to be marijuana smokers than groups who didn't have this dire diagnosis. Some studies, viewing things prospectively, suggested (note the word, please) that pot smokers were at double the risk of developing schizophrenia as those who never smoked the drug.

But, as the Time article noted  the portion of our US population diagnosed with this debilitating illness has remained constant at roughly 1%, and the current National Institute of Mental Health (NIMH) web-based discussion of schizophrenia agrees with this figure. It mentions that some drug abusers exhibit symptoms like those of patents with schizophrenia, but NIMH states that most researchers do not think that drug abuse is the cause of this mental illness.

A short piece from the CDC on childhood mental disorders in JAMA  for July 3, 2013, confirmed that schizophrenia is way down the list of mental disorders in US children. On the other hand, ADHD, behavioral/conduct disorders, anxiety, depression, use of illicit drugs or alcohol or cigarette, autism spectrum disorders and even Tourette syndrome (a neurologic disorder characterized by tics {repetitive involuntary movements and vocalizations} are listed as affecting multitudes of our youth.

In any given year, according to the CDC article, up to one fifth of our kids and adolescents have a mental disorder, while inpatient admissions have sharply increased for both mental health and substance abuse problems, especially for "mood disorders," e.g., anxiety and depression.

But there may be a subset of marijuana-using/abusing youngsters that merits special attention.

A 2011 Harvard Health Publications (HHP) blog piece by the then editor of the series, a woman whose bachelors degree was not in a medical field, but had a brother who developed schizophrenia, is titled "Teens who smoke pot at risk for later schizophrenia, psychosis."

I was concerned that she might have a biased slant on the disease, but impressed, as I read her blog piece by the articles she cited.

But then I went back to the articles themselves, as I routinely do. The first was in the British Medical Journal in 20111 and was a population based cohort study, a comparison of two different groups. The outcome was the "incidence and persistence of sub-threshold psychotic symptoms after adolescence." The verbiage used was that the use (and especially the continued use) of cannabis was a risk factor for developing severe mental illness.

I'd read the study as showing kids who end up psychotic often have smoked (or otherwise used) marijuana.

The second article cited was from the Archives of General Psychiatry, again a 2011 publication and was a meta-analysis (a study of a number of articles). The authors reviewed a large number of published research studies, picked 83 of them which met their standards for inclusion and pooled the results for statistical purposes.

That's a common way to look at data in order to have enough of it to reach a significant conclusion, which in this case was that the age of onset of psychosis was 2.7 years younger in the group who used cannabis.

Once again, that's only an association, but not a proof of causation.

The third article came from Lancet (in 1987) and was the result of  long-term followup of 45,550 Swedish military conscripts. Those who had smoked pot more than fifty times had a much higher rate of developing serious mental illness.

I want to go back to the blog in Harvard Health Publication, because here's where I have to differ with the author. Her statement that, "So far, this research shows only an association between smoking pot and developing psychosis or schizophrenia later on" makes sense; she admits the data don't prove marijuana causes psychosis.

But in the very next paragraph, she compares this research to that on cigarette smoking first being noted to be associated with lung cancer and later found to be a major cause of that disease.

Do troubled youngsters choice to smoke pot or does smoking it cause later troubles?

Don't get me wrong; today's marijuana is reputed to be much stronger than that which was around when I was a young research fellow and volunteered time at the Long Beach Free Clinic. And some of the studies I've read in the last week would certainly make me want to caution a teenager with a family history of schizophrenia that pot smoking is really risky for them.

Maybe we're going to see an epidemic of the disease in those of our younger generation who smoke marijuana and don't any family history of schizophrenia or other major mental illness.

But I sure haven't see any data yet that convinces me that's going to happen.