Apolgies in advance for the up coming post, i fear it would be a long one.
Right, the Keele University study carried out on behalf of the University by members of three departments ( Primary Care Research Center, Academic Psychiatry Unit and Department of Medicine Management.) Concluded, as published in the Schizophrenia Research Journal;
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.
Summed up, the study found through the examination of reported cases of Schizophrenia that there was no increase as the Cannabis use is believed to increase.
A couple of points about this first of all regarding the methods. The methods seem not to account for;
1) Mis-diagnosis by GP's. Cases can and are falsely diagnosed as other Mental Health issues, Anxiety disorders. However, false diagnosis works both ways so can be, somewhat convincingly, removed as a major criticism into more of a question.
2) We are relying seemingly on reported cases, what about cases that go un-reported? This again at first seems a strong criticism, but giving the debilitating nature of the illness it would be difficult to say that someone would not report such an illness. However, loners etc. may not have reported the illness and it is at least conceivable that a couple of cases at least could of gone unreported. However, would these couple of cases have changed the results, most likely not, this is were a problem with Quantitative research lies. Unless there is a numerical difference it does not count, however would one case of Cannabis induced Schizophrenia be enough to prove it as true, perhaps, this would of been better represented through Qualitative methods.
These concerns may cause problematic issues for the study, however, are these concerns enough to rubbish the study. Probably not, but, they're enough IMO to warrant a further study and prevent us from hailing this study as 100% prove.
Now, you need to appreciate that my field is Philosophy/Theology, i have studied the Philosophy of Science as apposed to Scientific methods, so my comments may be worded in an distinctly unscientific way. In addition to this, my comments will be based on the Philosophical problems with claiming Cannabis has huge amounts of medical value and in addition that it is a safe substance, particularly in relation to mental health.
Strangely, the mental health debate regarding cannabis has revolved around Schizophrenia. Reasons for this could be;
1) It is the most sensational and therefore is the best for an Anti-Cannabis Government to promote. Delete and impose the words ' Big Pharma Companies' if you wish.
2) It's the most debilitating and most pressing issue.
The first reason i feel relies heavily on many shaky assumptions, the Government is anti-Cannabis for it's own interests for example. While this can be argued, in some examples rather convincingly, to be true. I feel we should deal with solid facts, which i feel that the second issue is the most likely.
Therefore instead of throwing studies that suggest a link between Cannabis and Schizo, which number more in pro-link than anti-link. I will attempt to use other Mental Health issues and the links between Cannabis to show it is not that simple. This is because Cannabis and mental health goes beyond the Schizo link and i think you best find problematic issues when dealing with the issues regarding more common mental illness's. We need to understand that Mental Health goes beyond Schizo. and that we can find a greater number of studies which show both sides of the coin in Anxiety Studies, IMO.
Strangely i will turn to a study i use to illustrate the cause of legalisation, that is the study by Dr Feeny,G. et al in the Princess Alexanda Hospital, Brisbane, Australlia. The Journal entry is titled
Cannabis dependence and mental health perception amongst people diverted by police after arrest for cannabis-related offending behaviour in Australia. This study conculded that ;
Their high levels of psychopathology [ in users within the study ] suggest that they are better placed in healthcare rather than the criminal justice system, and that appropriately responsive mental healthcare programmes are needed
This study is interesting because it calls for legalization so cannabis can be treated as a health issue rather than a criminal one, so how can it fall into the category of ' The Big Pharmas made this because...[insert same old argument we've all heard here.] Yet it still finds problematic issues with Cannabis and mental health, in this case Anxiety disorders. Not convinced that Cannabis can be linked to mental illness's? Lets look at another.
A study from Italy concluded;
Frequent cannabis users consistently have a high prevalence of anxiety disorders and patients with anxiety disorders have relatively high rates of cannabis use
Problems with this study are quite obvious, did anxiety cause the use or did use cause the anxiety? I'm not suggesting this proves mental health issues with cannabis, however i am using it in conjunction with the other study to help show there are issues with cannabis and mental health, because a single study showed that there is no link between Cannabis use and rates of reported Schizo. Does not mean it proved no mental health issues. Hell, it doesn't mean it proved no Schizo link, just no reported Schizo link.
The above quote can be found in the Journal Alcholol and Drug Review under the title
Cannabis and anxiety: a critical review of the evidence. It was carried out by Crippa,J.A University of Sao Paulo in conjunction with Kings College London, Department of Psychiatry Neuroscience Hospital Clinic Barcelona, Spain.
So, what is the truth of the medical use of Cannabis? For me Costain,W. Sums it up well in his conculsion;
ABSTRACT: This study explored explanatory models used by individuals with schizophrenia in relation to continuing cannabis abuse. Cannabis is known to exacerbate positive symptoms, compound the effects of negative symptoms, and lead to relapse, having a negative effect upon quality of life. If this is so, why would people choose to continue the drug use? Most previous studies exploring this phenomenon have used quantitative methodology where the questions asked have been preset by the researchers and the subjective experience of the patient has been minimized. Qualitative methodology was utilized in this study in order to give voice to the patients' perspectives, and contribute to the knowledge of the frameworks of meanings employed by patients. The majority of participants in this study did not perceive that they had a mental illness and they held strong beliefs regarding the usefulness of cannabis. They gave explanations for their continuing cannabis use that expanded the understanding from previous studies. These included that they sought the drug effects of cannabis use for clarity of voices, control of symptoms, to feel normal, perceived improvement in cognitive function, reduced psychological pain and increased energy. These beliefs may influence a person's adherence with treatment and their future cannabis use. This research has implications for clinical practice as clinicians may lack insight into the importance of the phenomenological beliefs of a person with schizophrenia. This lack of insight by the clinician into the phenomenological beliefs may impact on the development of a therapeutic relationship.
People have strongly held belief Cannabis has a positive impact on their mental health issue. However, this imo is confused with the Euphoria that Cannabis causes, it's not helping your illness, it's making you ok with it and happy. It helps people forget about their problem, not cure it. This incidentally is why i laugh when people say that Medical professionals are only interested in helping symptoms. This is also why i get pissed off and take the piss out of people claiming Cannabis as this cure all substance with no links towards mental health issues, this is far beyond the nice world of sitting down and smoking a joint with your friends, mental health problems are life destroying and by telling people that Cannabis can help them is masking their problem and hurting them in the long run. There is no study which comprehensively proves that Cannabis has links to mental health issues, just as there are none that prove Cannabis has no links to mental health issues. The problem is, that people take this as meaning that there is no link to negative mental health issues while forgetting the other side of the coin. This is dangerous, as there is imo, and actually many others views as well, enough evidence to show at the least some evidence, at the most probability, that Cannabis can be harmful for peoples mental health.
The uncomfortable truth about Medical Cannabis is this, it helps people forget about Chronic Pain, helps people eat and sleep and helps a limited number of chronic lifelong medical problem, Crohns disease being the best example of this. However, it is not a cure all herb, it's simply not. It has dangers, dangers that people should be as aware of as the positive aspects of Cannabis.
Before people start telling me that i am blind to the magic of Cannabis, do me a favor, sign up to a journal site. Do your own research, don't ignore the problematic issues with Cannabis because it flies in the face of your preferred recreational drug, actually look at the research and critics of research by yourself without the interpretor found on a pro-Cannabis site and use your God given free mind to think for yourself. Some people will never be convinced that Cannabis isn't a 100% safe and wonderful substance, i think this is because they feel the need to justify their consumption in some way. But, don't mistake your want of justification as actual scientific evidence.
Cannabis is not the evil weed some media sources want to portray, it is not the benign substance the other side of the coin want to portray. It's truth, as with everything in the world, is in the grey areas. It can be helpful, equally it can be dangerous. Not enough is known to claim either way, i am not rubbishing Cannabis as a medical substance, i am saying you people claiming it is a useful one for a wide range of illness's are wrong. You are. I know that is blunt, but some of you don't seem to get it when it's pointed out nicely. You do not have enough evidence to claim that it is. That's why the reasonable thing to do is to cast doubt and continue to study until we have enough evidence to prove either way.
Although there has been considerable research into the adverse effects of cannabis, less attention has been directed toward subjective effects that may be associated with ongoing cannabis use. Examination of self-reported cannabis effects is an important issue in understanding the widespread use of cannabis. While reviews have identified euphoria as a primary factor in maintaining cannabis use, relaxation is the effect reported most commonly in naturalistic studies of cannabis users, irrespective of the method used. Self-reported effects in 12 naturalistic and 18 laboratory studies were compared. Regardless of methodology there was considerable variation in the effects experienced. Variation has been reported in terms of opposite effects being experienced by different individuals, variation of effects by individuals within a single occasion and between occasions of use. Factors that might explain this variation are outlined. Limitations of the available literature and suggested directions for future research are discussed.
Green,B. et al, Being stoned: a review of self-reported cannabis effects, The Drug and Alcohol review Journal.
My point illustrated here is that the effects of Cannabis vary HUGELY, anecdotal evidence is not enough. If you react badly to Cannabis don't assume that it's the same for everyone, the same works for medical use.
Be safe, use your mind to think freely and don't rely on interpretors to tell you what you should think, make the effort to do it yourself, the you'll no for sure.
). But, if one is to put another Anti-Cannabis study as stand alone proof you watch the sparks fly ' That study has questionable issues...It doesn't show a 100% link so it can't be true.' Why not, for the love of God, show the same level of scrutiny of the pro Cannabis studies? 
