More threads by David Baxter PhD

David Baxter PhD

Late Founder
THC may Cause Schizophrenia-like Symptoms
Jun 15 2004
by Leonard Holmes, Ph.D.,

Yale University researchers have shown that active ingredient in marijuana can cause transient schizophrenia-like symptoms ranging from suspiciousness and delusions to impairments in memory and attention in some patients. The study was an attempt to clarify a long known association between cannabis and psychosis in the hopes of finding another clue about the pathophysiology of schizophrenia.

Lead author D. Cyril D'Souza, M.D., is quoted in a Yale press release as saying "Just as studies with amphetamines and ketamine advanced the notion that brain systems utilizing the chemical messengers dopamine and NMDA receptors may be involved in the pathophysiology in schizophrenia, this study provides some tantalizing support for the hypotheses that the brain receptor system that cannabis acts on may be involved in the pathophysiology of schizophrenia."

The researchers administered various doses of delta-9-THC, the main active ingredient in marijuana, to subjects who were screened for any vulnerability to schizophrenia.

Some subjects developed temporary symptoms similar to those of schizophrenia, usually lasting one half hour to one hour. The symptoms included suspiciousness, unusual thoughts, paranoia, thought disorder, blunted affect, reduced spontaneity, reduced interaction with the interviewer, and problems with memory and attention. As expected THC also induced euphoria. A somewhat more surprising finding was increased levels of the stress hormone cortisol. There were no side effects in the study participants one, three and six months after the study.

The Yale researchers suggest that their go along with several other lines of evidence that suggest a contribution of cannabis and/or abnormalities in the brain cannabinoid receptor system to the pathophysiology of schizophrenia. Such research is in the very early stages, but it does back up clinical evidence that marijuana can cause paranoia and schizophrenic-like symptoms in some people. If schizophrenia runs in your family you should probably avoid marijuana.

Reference: Neuropsychopharmacology, Advanced Online Publication (June 2, 2004)

David Baxter PhD

Late Founder
Study finds no proof cannabis induces schizophrenia

Study finds no proof cannabis induces schizophrenia
August 19, 2004

AMSTERDAM (Reuters) - There is no scientific proof that cannabis use induces schizophrenia, Dutch scientists say, questioning recent research and an argument the Dutch government uses to crack down on marijuana-selling "coffee shops."

In an article in this week's Magazine for Psychiatry, a peer-reviewed journal, the three authors say that on the basis of currently available data "there is no justification for the proposed closure of coffee shops."

Often the first symptoms of schizophrenia occur during adolescence, when people start to experiment with drugs, but the scientists believe cannabis use only has a negative effect on people already genetically predisposed to the mental illness.

"It is therefore advisable that youngsters with a family history of schizophrenia and patients with a schizophrenic disorder be discouraged from using cannabis," the report said.

Subsequent Dutch governments have tightened rules on the sale of marijuana in government-regulated coffee shops, resulting in a significant reduction in the number of cannabis cafes.

A ban this year on alcohol in coffee shops will be followed by a ban on tobacco in 2005, outlawing all smoking on the premises.

There are around 780 coffee shops in the Netherlands of which 270 are in Amsterdam, according to 2002 figures.
I read an interesting book (This Stranger My Son) about a boy who had suffered from paranoid schizophrenia all his life, and after hearing his mother describe some of the peculiarities he had (very excessive appetite, exceptionally good hearing, an almost imperviousness to harsh weather or pain) - and of course, his seemingly lack of discourse to anyone outside his home, I don't know if it's such a far stretch to say there possibly may be a link between the two. Cannabis is notorious for the "munchies", its enhancing auditory effects, pain relief, and of course for making people more paranoid, and non-sociable...

This is of course only one case in the kajillions of schizophrenics out there, but an interesting correlation between the psychoactive and mental illness nonetheless.

David Baxter PhD

Late Founder
I think, as you will see from more recent threads on this topic, that this is still an open question. There seems to be growing evidence that in certain people cannabis may trigger psychotic reactions. On the other hand, there are probably millions of marijuana smokers out there -- why don't ALL of them experience psychotic breaks? Presumably, there is some susceptibility or vulnerability in certain people that leads them to this outcome but what exactly that is isn't clear. And that means at present we don't know who is at risk and who is not.
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