Tag Archives: cannabis

Another Study, Another Look at Pot

A blogger recently sent the following to counter the first study.  I don’t know but we need to look at all sides of any issue.

Schizophr Res. 2009 Sep;113(2-3):123-8. Epub 2009 Jun 27.

Assessing the impact of cannabis use on trends in diagnosed schizophrenia in the United Kingdom from 1996 to 2005.

Frisher M, Crome I, Martino O, Croft P.

Department of Medicines Management, Keele University, Staffordshire, UK. m.frisher@keele.ac.uk


A recent systematic review concluded that cannabis use increases risk of psychotic outcomes independently of confounding and transient intoxication effects. Furthermore, a model of the association between cannabis use and schizophrenia indicated that the incidence and prevalence of schizophrenia would increase from 1990 onwards. The model is based on three factors: a) increased relative risk of psychotic outcomes for frequent cannabis users compared to those who have never used cannabis between 1.8 and 3.1, b) a substantial rise in UK cannabis use from the mid-1970s and c) elevated risk of 20 years from first use of cannabis. This paper investigates whether this has occurred in the UK by examining trends in the annual prevalence and incidence of schizophrenia and psychoses, as measured by diagnosed cases from 1996 to 2005. Retrospective analysis of the General Practice Research Database (GPRD) was conducted for 183 practices in England, Wales, Scotland and Northern Ireland. The study cohort comprised almost 600,000 patients each year, representing approximately 2.3% of the UK population aged 16 to 44. Between 1996 and 2005 the incidence and prevalence of schizophrenia and psychoses were either stable or declining. Explanations other than a genuine stability or decline were considered, but appeared less plausible. In conclusion, this study did not find any evidence of increasing schizophrenia or psychoses in the general population from 1996 to 2005.

PMID: 19560900 [PubMed – indexed for MEDLINE]


More later… Sharon O’Hara

Cannabis Linked To Psychosis – Not Good Health

I voted yes for the use of marijuana for medical purposes in our state – unknowing Federal law still made it illegal.  Today I would vote a resounding NO – not in a cigarette form anyway – not as long as we have a Federal law against it and now because of the following article connecting cannabis use to psychosis.

I know people smoke pot but not around me.  I might have tried it at a young age but it wasn’t around then and later, when it was hitting the Kitsap schools my children attended I was too busy and no one I knew smoked it.  The subject didn’t come up.

Let me be clear:  I don’t care what people do with their own lives.  I smoked 40 years and understand the connection and addiction to drugs.

Trouble is all these years later I’ve got health issues that seem to stem directly from my own 40 year smoking addiction and have gathered opinions about it to share here such as….get educated about it first.

If one is going to smoke, use cannabis and other illegal drugs, then learn about them, study all you can find out about them – then from the basis of full  knowledge what you might be getting into long term – make your decision.  It is your decision, not mine.  Just get educated about it.  And that is why I’ve posted the following new information here.


Cannabis Link To Psychosis

A new study has provided the first conclusive evidence that cannabis use significantly hastens the onset of psychotic illnesses during the critical years of brain development – with possible life-long consequences.

The first ever meta-analysis of more than 20,000 patients shows that smoking cannabis is associated with an earlier onset of psychotic illness by up to 2.7 years.

The analysis, by an international team including Dr Matthew Large, from the University of New South Wales (UNSW) School of Psychiatry and Sydney’s Prince of Wales Hospital, is published in the prestigious journal Archives of General Psychiatry.

In partnership with St Vincent’s Hospital and The George Washington University School of Medicine and Health Sciences, the study set out to establish the extent to which use of cannabis, alcohol and other psychoactive substances affects the age at onset of psychotic illnesses such as schizophrenia.

Cannabis is the most widely used illicit drug in Australia with 33.5% of the population reporting use at some time, according to the 2007 National Drug Household Survey. Some 18% of all secondary school students aged 12-17 reported using the drug at some time in their life, according to the 2004 Secondary School Survey. (UNSW’s National Cannabis Prevention and Information Centre.)

Building on several decades of research, the finding is an important breakthrough in the understanding of the relationship between cannabis use and psychosis, Dr Large said.

A number of previous studies have found an association between psychosis and the use of cannabis, alcohol and other psychoactive substances. However, the aim of this study was to specifically show the extent to which this is caused by cannabis use alone, he said.

The current findings support the view that cannabis use precipitates schizophrenia and other psychotic disorders, perhaps through an interaction between genetic and environmental disorders or by disrupting brain development, the team notes.

“The study re-analysed the results from 20,000 patients with schizophrenia or other psychotic illnesses from 83 previous studies. The study used meta-analysis – a modern statistical method – to show that an earlier onset of severe mental illness among substance users is a result of cannabis use, and cannot be explained by other factors such as alcohol use,” Dr Large said.

“Results of this study are conclusive and clarify previously conflicting evidence of a relationship between cannabis use and the earlier onset of a psychotic illness, with evidence supporting the theory that cannabis use plays a causal role in the development of psychosis in some patients.”

Dr Large said there was a high prevalence of substance use among individuals treated in mental health settings, and patients with schizophrenia were more likely to use substances than members of the wider community.

“The study raises the question of whether those substance users would still have gone on to develop psychosis a few years later.

“However, even if the onset of psychosis were inevitable, an extra two or three years of psychosis-free functioning could allow many patients to achieve important developmental milestones of late adolescence and early adulthood that could lower long-term disability arising from psychotic disorders,” Dr Large said.

“The results of this study confirm the need for an ongoing public health warning about the potentially harmful effects of cannabis.”


More later…. Sharon O’Hara