Scare headlines splashed around the world say smoking pot will change your brain chemistry, warp your memory and give you schizophrenia. The media is trying to hook an audience with the case that all the recent news supporting marijuana may be wrong. But they’re the ones who are mistaken.

A recent study does suggest heavy cannabis use can lead to changes in brain structure that resemble those found in schizophrenics. And, as pretty much everyone familiar with weed already knows, chronic use can impede memory.

What’s the real story?

But the results only apply to tokers who started using between ages 16 and 17, teens who are not supposed to consume marijuana, even in states where it’s legal. The only minors who are allowed to use pot are MMJ patients with debilitating illnesses, and they probably number in the hundreds nationally.

Marijuana Schizophrenia

What’s more, there’s no evidence of a causal link between weed and schizophrenia, in either direction. In other words, the study doesn’t suggest either that pot causes schizophrenia or that schizophrenia leads people to smoke pot, though Schizophrenia patients do so at nearly twice the rate of the general population.

Even the study’s findings are inconclusive. It’s possible the brain changes seen by researchers in young tokers triggered heavy pot use rather than the other way around.

The study was conducted by researchers at Northwestern University and published in the journal Schizophrenia Bulletin.

It found that the younger the smoker, the more profound the changes in brain structure. It also found that heavy marijuana users scored much lower than non-smokers on memory tests.

Conflicts in the Study Results

The biggest problem with the study and the media explaining it is that they all imply the results apply to adults as well as children. They don’t. Like previous studies on humans that have found links between schizophrenia and weed, this one focused only on young adults.

The headlines also suggest the study proves pot causes schizophrenia and other mental illnesses. It does no such thing. Nor does any previous research.

Studies in the past, on rats and humans, have suggested a link between psychotic disorders and marijuana use, but the evidence is conflicting. Some have shown similar changes in brain chemistry among cannabis smokers, while others have shown the drug may offer medical benefits to patients.

The Study: Marijuana and Schizophrenia

The Northwestern study involved about 100 teenagers in four groups: mentally healthy teens who had never used, mentally healthy teens who had, teens with schizophrenia who had never used, and teens with schizophrenia who had.S

The subjects underwent MRI scans, which showed weed users had experienced shrinkage in regions of the brain that handle working memory. This translated to dramatically lower scores on memory tests, compared to non-users.

“The abuse of popular street drugs, such as marijuana, may have dangerous implications for young people who are developing or have developed mental disorders,” said study author Dr. John Csernansky, chair of psychiatry and behavioral sciences at Northwestern University’s Feinberg School of Medicine and Northwestern Memorial Hospital.

It’s worth noting that while rates of marijuana use have increased substantially in recent decades, rates of schizophrenia in the American population have not – an argument against the theory that weed causes the disease.


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