Schizophrenia is the most common psychotic mental disorder with an estimated prevalence of 2. 5 million of the U. S. population. A popular theory of the cause of schizophrenia is the Dopamine Theory, which is that schizophrenia is related to excess activity of the neurotransmitter dopamine. Cannabis, like all drugs and alcohol, increases activity in the dopamine system. The fact that cannabis directly affects the dopamine system suggests that it is plausible that it plays a role in psychosis.
In most people dopamine just elicits a pleasure response, but in some people increasing dopamine activity can induce psychotic symptoms associated with schizophrenia (Murray, 2005). The aim of this study is to see whether reducing cannabis use will have any effect on symptoms of schizophrenia using participants who smoke cannabis regularly and who have been diagnosed with schizophrenia. It is expected that there will be a negative linear relationship between schizophrenic symptoms and the amount of cannabis used, i. . the symptoms decrease as the amount of cannabis used decreases. Introduction Schizophrenia is the most common psychotic mental disorder, and is characterised by disturbances in thought, emotion and behaviour; disordered thinking where ideas are not logically related; faulty perception and attention; a lack of emotional expressiveness, or at times inappropriate expressions; and disturbance in movement and behaviour, such as a shuffling gait or dishevelled appearance.
Patients with schizophrenia may withdraw from people and from everyday reality, often into a life of delusions and hallucinations. Delusions and hallucinations may cause considerable distress to both patients and their families, as their symptoms make stable employment difficult, often leading to impoverishment and homelessness. Strange behaviour and social skills deficits lead to loss of friends, a solitary existence and stigmatization. Schizophrenia affects both men and women equally and usually appears in late adolescence or early adulthood.
People with schizophrenia typically have a number of acute episodes of their symptoms and less severe but still very debilitating symptoms between episodes. Comorbid substance abuse occurs in about 50 per cent of patients (Kosten & Ziedonis, 1997). Schizophrenia is a relatively common disease, with an estimated prevalence of 2. 5 million of the U. S. population. The symptoms that are most commonly associated with sschizophrenia are called positive symptoms, which include thought disorder, delusions, and hallucinations. Thought disorder is the diminished ability to think clearly and logically.
Often it is manifested by disconnected and irrational language that renders the person with schizophrenia incapable of participating in conversation, contributing to his alienation from his family, friends, and society. Delusions are common among individuals with schizophrenia, and are beliefs which are held contrary to reality and firmly held in spite of disconfirming evidence. Persecutory delusions, for example where a patient believes that they are being spied on by others and plotted against, were found in 65% of a large, cross-national sample of people diagnosed with schizophrenia (Sartorius, Shapiro & Jalabonsky, 1974).
Patients with schizophrenia frequently report that the world seems somehow unreal to them. A patient may become so depersonalised that they feel as if their body is a machine. The most dramatic distortions of perception are hallucinations, sensory experiences in the absence of any relevant information from the environment. They are more often auditory than visual; 74% of one sample of schizophrenia patients reported having auditory hallucinations (Sartorius et al. , 1974). Schizophrenia is a very heterogeneous disorder.
Therefore, the DSM-IV-TR (2000) categorizes schizophrenia into subtypes. For example disorganized schizophrenia (characterised by disordered and inappropriate behaviour and incoherent, random speech); catatonic schizophrenia (characterised by abnormal motor movements and peculiar gestures); paranoid schizophrenia (characterised by the presence of prominent delusions and often read significance into trivial activities of others, e. g. that the frequent appearance of the same person in a street where they walk may be interpreted as them being watched).
A popular theory of the cause of schizophrenia is the Dopamine Theory, which is that schizophrenia is related to excess activity of the neurotransmitter dopamine. This theory is based principally on the knowledge that drugs that are effective in treating the psychotic symptoms of schizophrenia reduce dopamine activity. Furthermore, post-mortem studies of brains of schizophrenia patients have revealed that dopamine receptors are greater in number or are hypersensitive in some people with schizophrenia (Hietela et al, 1994; Tune et al, 1993; Wong et al, 1986).
Having too many receptors would be functionally akin to having too much dopamine itself. The main active ingredient in cannabis is delta-9-tetrahydrocannabinol (THC), and this, together with cannabinol and cannabinoid, produce the main psychoactive effects. The effects of cannabis vary from person to person, but research has revealed some typical effects. Users tend to report euphoria and relaxation at lower doses, and fear and paranoia at higher doses. Sensory enhancement is a common effect, as is creative thought and personal insight. Negative effects include short-term memory impairments, mental fogginess and slowed thinking.
The prevalence of cannabis use has been reported at about 8 per cent of adolescents aged 12-17. Cannabis use tends to be higher in men than women (e. g. Johnston et al, 2001). Cannabis, like all drugs and alcohol increases activity in the dopamine system. The fact that cannabis directly affects the dopamine system suggests that it is plausible that it plays a role in psychosis. In most people that just gives pleasure, but some people appear to be vulnerable, and increasing dopamine activity can induce psychotic symptoms associated with schizophrenia (Murray, 2005).
Whereas some people can smoke cannabis every day and do not become psychotic, a minority of people do become psychotic, so there might be some difference in genetic susceptibility, particularly in the genes which metabolize dopamine. A gene involved in the metabolism of dopamine, called COMT breaks down dopamine in the frontal lobes of the brain. A study at the Institute of Psychiatry, London, has found that a particular type of COMT gene can increase a person’s susceptibility to cannabis induced schizophrenia or psychosis up to ten fold.
Those who smoked the drug regularly at 18 were 1. 6 times more likely to suffer serious psychiatric problems, including schizophrenia, by their mid-20s. For those who were regular users at 15, the stakes were even higher, with their risk of mental illness being 4. 5 times greater than normal. (Murray, et al, 2005). A previous Swedish study showed that young men using large quantities of cannabis at conscription were at increased risk of being admitted for schizophrenia over the subsequent 15-year period.
The association between level of cannabis consumption and development of schizophrenia during a 15-year follow-up was studied in a cohort of 45,570 Swedish conscripts. The relative risk for schizophrenia among high consumers of cannabis (use on more than fifty occasions) was significantly greater compared with non-users, indicating that cannabis might be an independent risk factor for schizophrenia (Andreasson, 1987). These findings have been replicated in other studies (e. g. Van Os et al, 2002).
Recent research has shown that even small amounts of THC can lead to paranoia, hallucinations, delusions and other effects more commonly associated with schizophrenia and other mental illnesses. Although the symptoms were transient, half of those taking part in the study developed schizophrenia-like symptoms. When the strength of the drug was increased from a level between half and one and a half joints to the amount likely to be found in two joints, 60 per cent suffered symptoms usually seen in mental illness. Schizophrenics appeared even more vulnerable to the drug, despite their illness being controlled with medicine (D’Souza, 2004).
The leading researcher of this study, Dr D’Souza, of Yale University School of Medicine in the US, said: “We had a subject who refused to answer any of the questions we asked her because she was convinced that my staff could read her mind, so she didn’t need to answer the questions…we had another subject who refused to continue with any of the tests because she thought we were trying to make her look stupid. ” (D’Souza, 2004). British researcher Philip McGuire,a professor of psychiatry, has recently claimed that cannabis triggers paranoia by tampering with the area responsible for inhibition and restraint.
For example, if you had a nagging thought about whether your boss was planning to sack you, then these worrying thoughts are normally controlled and suppressed by this region, but if you stop it from working, these thoughts might become more prominent. Although these previous studies to seem to indicate that cannabis can cause generate paranoia and psychotic symptoms associated with schizophrenia to occur in individuals genetically predisposed psychosis, no study has yet to examine whether reducing cannabis will have an effect on the symptoms of schizophrenia.
The aim of this study will be to see whether reducing cannabis usage will reduce the symptoms of schizophrenia. It is expected that there will be a negative linear relationship between schizophrenic symptoms and the amount of cannabis used, i. e. the symptoms decrease as the amount of cannabis used decreases. Method Participants The participants will be drawn from a sample of people who have been diagnosed with schizophrenia and who smoke cannabis regularly (at least once a week, for three months prior to the study).
The first group will consist of participants who continue to smoke the same amount of cannabis throughout the study. The second group will consist of participants who reduce their cannabis usage by half, and the third group will consist of those who abstain from using cannabis for two months. There will also be a control group which will consist of individuals who have been diagnosed with schizophrenia and who do not smoke cannabis. This will determine whether there are any confounding factors that may influence the scores. A T-test will be performed on the two sets of scores from the control group (before and after).
If there is a significant difference between them, then it is possible that there are confounding factors. Procedure Recruitement will be done via internet advertising on websites aimed at people suffering with schizophrenia. Participants expressing an interest will be asked to leave their contact details. They will then be contacted by the researcher and given information on the study, including information on the three different condition groups. In this study, participants cannot be randomly allocated into a condition as they need to agree and adhere to a pre-arranged amount of cannabis usage.
After an adequate ‘cooling off’ period (at least twenty four hours) participants will be contacted again and asked if they agree to participate. If they do will be interviewed using questions from the Structured Clinical Interview for DSM-IV-TR (SCID), an instrument with proven reliability and validity in diagnosing schizophrenia. The SCID is a semi-structured interview for making the major Axis I DSM diagnoses. (Spitzer, et al, 1992). After two months, participants will then be interviewed using the SCID again. In between these two testing periods, contact will be maintained between the researcher and the participants.
This is because firstly, participants will need to be drug-tested to ensure that participants are adhering to the arrangement, and secondly, keeping in contact will minimize the chances of the participant dropping out of the study. ANOVA will be performed the sets of scores to test for any significant main effects. The design of the study will be between-groups variance. Independent variable: Amount of cannabis smoked Dependent variables: 1) Scores from schizophrenics who continue to smoke the same amount of cannabis 2) Scores from schizophrenics who reduce their cannabis usage ) Scores from schizophrenics after abstinence Limitations Participants might be difficult to recruit and their doses difficult to monitor. It will be necessary to monitor whether the participants’ are adhering to the prearranged amount of cannabis usage . Furthermore, it may be that the effect of cannabis remains for longer then the two month period of the study. However, a longer study will create a very high likelihood that participants will drop-out rate or not adhere to the abstinence/ reduction agreement. Also, this study aims to provide support for previous studies, rather than seeking conclusive evidence.