Marijuana (Cannabinoids)Schizophrenia

Cannabis and the risk for developing psychosis

Researchers at the University of Amsterdam, in the Netherlands, hypothesized that cannabis use (or a cannabis use disorder) at a younger age relates to a high-risk symptoms at a younger age.

And a second study comes to rather odd conclusions about marijuana and schizophrenia severity.

First, the details.

  • 68 people with an ultra-high risk for psychosis were interviewed to assess their cannabis consumption.
  • 9 high-risk symptoms were selected for evaluation because of their known relation with cannabis use.

And, the results.

  • Among the participants, 35 used cannabis (52%), of whom 15 had used it recently.
  • 22 participants were cannabis abusers or cannabis-dependent (32%) in the past.
  • Starting to use cannabis at a younger age was significantly related to younger age of onset of the cluster of symptoms and to 6 symptoms individually.
  • Younger age at onset of a cannabis use disorder was significantly related to younger age of onset of the cluster of symptoms and to 6 symptoms individually.
    • Cannabis use disorders include problems such as loss of major role functions and repeated legal problems.

The bottom line?

The authors concluded, “Cannabis use or a cannabis use disorder at a younger age in a group with an ultra-high risk for transition to psychosis is related to onset of high-risk symptoms for psychosis at a younger age.”

In other words, cannabis use at a younger age relates to high-risk symptoms for psychosis at a younger age.

OK, that’s pretty straightforward. However, the picture becomes less clear when we consider another recently published study, which suggests that people with schizophrenia who smoked pot differ from those with schizophrenia who never smoked pot.

Those who smoked marijuana were comparatively higher functioning. That is, they had “significantly better performance on measures of processing speed, verbal fluency (animal naming), and verbal learning and memory.”

The authors of the study don’t believe that cannabis improves cognition per se. They suggest that marijuana smokers have inherently better social skills, making them more likely to encounter the drug.

That seems like a stretch. Before coming to any conclusions, another study (probably more) should be done to confirm these results.

But lets get back to reality. It’s perverse to be drawn into a discussion about the “benefits” of a drug (marijuana) that’s associated with a serious disease (schizophrenia). Why would a rationale person knowingly do anything that increases their risk of schizophrenia, regardless of the level of function?

More on the association between marijuana and mental disease can be found here.

8/15/10 23:14 JR

Hi, I’m JR

John Russo, Jr., PharmD, is president of The MedCom Resource, Inc. Previously, he was senior vice president of medical communications at, a complementary and alternative medicine website.