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The relationship between cannabis use and mental health disorder

By derpahderp, Nov 21, 2012 | | |
  1. derpahderp
    View attachment 29836
    This assignment evaluates the relationship between cannabis use and mental health disorder related to it in Australia. Recent national data reflects that cannabis use was at its peak in 1998 when over 60% of people aged 20-29 were reported having used cannabis.

    Since then various studies have found co relation between cannabis use causing no mental health issues and cannabis use causing schizophrenia and psychosis. Recent studies have found that cannabis is recognized in Australia as the third most prevalent drug of dependence following alcohol and tobacco. About 10% of people who try cannabis will develop dependence at some point in their life. Studies have found relationship between weekly frequency of cannabis use and mental illness such particularly psychosis, schizophrenia, anxiety and depression (www.mhca.org.au).


    Cannabis is a plant contains a psychoactive molecule that produces a high associated with this drug. The psychoactive product contains dried flowers and leaves of plants selected to produce high levels of tetrahydrocannabinol (www.dictionary.com). There is a significant and growing research on the relationship between mental illness and cannabis use in Australia. The evidence supports the association between mental illness and regular cannabis use. The evidence states that regular cannabis use from young age will increases the risk of mental illness since there is genetic vulnerability to psychosis being which can be triggered by cannabis use. Evidence shows that cannabis use facilitates schizophrenia in people who have family history of mental illnesses. The average first use of cannabis users is now 14.9 years. This is of a very important concern in Australia as this is the age at which there are psychological changes in brain. Psychosis is an abnormal condition of the mind in generic psychiatric term for a mental state is often described as a loss of contact with the reality. This disorder can disable the normal functioning of the brain. This malfunction in brain causes people with elevated risk of death by suicide. Thus it is important to analyse the evidence carefully in order to make conclusions and recommendations (Hall et al, 2004).

    Relationship between Mental Illness and Cannabis.

    Certain pockets of Australian population consume cannabis in form of heating or ignition combined with inhalation of smoke or oral consumption of the plant itself mixed into a food medium. The other way that individuals consume cannabis is by vaporization, which causes the active ingredients to evaporate into gas without burning the plant material. This is generally done by boiling the ingredients of cannabis plant. Once these vapours are inhaled, it produces various short term and long term effects. The short term effects range from sleepiness, difficulty keeping track of time, impaired or reduced short term memory. In my general practice I have observed that the patients consuming high amount of cannabis find it hard to communicate and focus. They are generally slower to react and have increased heart rate, heart palpitations and show signs of psychological dependence on cannabis drug consumption. Their reasons for addiction generally range from recreational purposes and sometimes to escape their present hardships in life (Personal Communication, Clinical Placement, 2010).

    Evidence shown by scientific research shows that potential harm of cannabis use is generally and especially in vulnerable groups such as Aboriginal, young people, people belonging to poor socio economic background. The habit starts from peer pressure and gradually becomes an addiction. Rates of cannabis use by people with mental illness such as anxiety and depression also show heavy use of cannabis use.(Castle, 2004)

    The self medication hypothesis states that people experiencing signs of mental health disorder consume cannabis in order to alleviate or increase symptoms. There have been longitudinal studies to determine whether the mental illness is related to cannabis use. The hypothesis covers two scenarios –that cannabis initiates mental disorder that were previously lying inactive and that cannabis causes mental health illness who would not otherwise develop them. Thus research has been conducted on biological mechanisms such as effects of cannabis on brain chemistry and its effects on people without genetic predisposition to mental illness. Other social effects are taken into consideration when researching on cannabis users exposed to factors such as poor mental health, substance using peers, school dropout, unemployment and crime. It is a difficult to justify the effects of cannabis on an individual if many variables co exist both for the cannabis user and people with other social vulnerabilities including family difficulties. Thus it is possible that there is a common genetic factor that predisposes individuals to cannabis use and mental illness (Patton et al, 2002).

    According to D’Souza et al (2004) there is little dispute that cannabis can produce short term recurrences of pre existing psychotic symptoms. However there is no evidence relating to the fact that cannabis actually causes schizophrenia or other psychotic illness in long term (Johns, 2001). Research also shows that cannabis can also amplify a pre existing thought in an individual. These thoughts tend to overwhelm the individual causing severe reactions by individuals including suicide and self harm in extreme cases. In order for ascertain the research Hill (1965) states that following criteria must be met: Strength, consistency, specificity, temporality, biological gradient, coherence and plausibility. Every case needs to support each criteria to make the hypothesis stronger.

    Relationship between Cannabis consumption and Psychosis

    A recent study conducted by Hldes et al (2006) states that there is a two way relationship between psychosis and cannabis which states that regular use of cannabis is associated with higher risk of psychotic relapse. Many longitudinal studies have found that the mental illness particularly psychosis leads to increased use of cannabis.

    Research conducted by Hall et al (2004) states that most common symptoms related to the individuals with psychosis smoking cannabis were sudden confusion which were generally related to delusions and hallucinations. Their emotional state became unstable and showed signs of paranoid symptoms. These findings have been supported by individuals suggesting that they took large doses of cannabis product. Most of these people had no family history of psychosis. Their symptoms were gone once the individuals stopped their cannabis intake. These symptoms were seen back within days once the individuals started cannabis consumption again. Thus this evidence supports the hypothesis that the regular use of cannabis increases chances of psychosis in an individual.

    On the other hand the other hypothesis can be argued that cannabis intake does not support psychosis. There have been number of studies conducted that have compared people with people who have mental illness post cannabis use and who have developed mental illness prior to cannabis consumption. There is always a little variation in the results. According to Mental health council of Australia, there have been number of researches that have been conducted investigating the cannabis use among individuals with psychotic disorders and found that they were not significantly different from the general population. A range of motive can be grouped into following four categories: coping with unpleasant affect (to relieve emotional distress), enhancement (to have fun), social interaction (to affiliate with others), confirming (to fit in) (www.mhca.org.au)

    The evidence obtained shows that the first two tend to be heavy cannabis consumers and the later two are just recreational. The first two consume cannabis to relieve themselves from emotional distress, psychotic symptoms and medication side effects which lead them to consume heavy amounts of cannabis in order to feel that state of mind and emotion. People with psychosis initially use substance to change their emotional state and facilitate social contact. They then develop dependence on this substance stating,” If I don’t smoke then I will not be able to cope.” These individuals then have belief that cannabis is the only way out thus worsening their psyche and this will lead to worsening cannabis dependence (Spence in Castle and Murray, 2004)


    Various cases and individual analysis state that there is a strong connection between cannabis consumption and psychosis. The hypothesis states individuals consuming cannabis have developed symptoms of psychosis and these individuals have normalised once they stopped consuming cannabis. Thus, there is some evidence that suggest that cannabis consumption will impact the psyche of an individual but these findings are inconclusive at this stage as it fails to take into consideration other variables such as socioeconomic background, mental state, lack of family and community support.

    Relationship between Cannabis Consumption and Schizophrenia

    Schizophrenia is a mental illness caused by disintegration of thinking process and disorientated emotional response. It usually consists of hallucinations, paranoid, disorganized speech and thinking process with social and occupational dysfunction, withdrawal from reality, social apathy (www.dictionary.com)

    According to research by Mental Health Council of Australia relationship between Schizophrenia and cannabis use is growing though by no means comprehensive. Schizophrenia affects one percent of the Australian population. Smaller but substantial bodies of research exist such as depression and anxiety. In some cases, Schizophrenic patients had previous symptoms of psychotic illness (Hall et al, 2004).

    In research conducted on 100 young people consuming high amount of cannabis, 49% male with an average age of 19.3 years were identified at ultra high risk of psychosis. Schizophrenia was the symptom with presence of other acute psychotic symptoms. This research is very difficult due to the fact that there are many variables that co exist both cannabis users with mental health illness and non cannabis users with mental health difficulties have similar behavioural problem. Most of them have substance abuse history, unemployment and life time on benefits past. It can be possible that these are the common genetic factors in both cannabis users with mental health issues and non cannabis users with mental health issues (www.mhca.org.au).

    Longitudinal studies show that continuous cannabis consumption in people with schizophrenia is associated with worse mental health outcome in terms of more severe symptoms and thus there is a greater chance of relapse and more psychosocial issues. Thus frequent cannabis use is associated with a higher risk of psychotic relapse and a more increased risk of cannabis relapse (Hides et al, 2006). Studies conducted by Arsenault et al, (2004) cite cross national surveys from USA, Netherlands and USA found rates of cannabis consumption among people with Schizophrenia was double than those of general population. Thus following conclusions were derived from these findings:

    Evidence of self medication of cannabis because of pre existing Schizophrenia due to the mental health issues caused by schizophrenia related to negative symptoms may be a factor in continuous Cannabis consumption. There have been consistent longitudinal studies stating that cannabis precipitates schizophrenia and many other psychosis related symptoms in people who are vulnerable because of their family background. The rate of schizophrenia has remained stable or decreased with increases in cannabis use over the past few decades. Overall longitudinal studies conducted by Nemesis study from Holland and New Zealand have made these findings that conclude that cannabis can be considered a casual factor in schizophrenia. Research has found that alleged increases in cannabis use over past two decades have not affected increase in rate of schizophrenia. However vast number of people who consume cannabis have not developed schizophrenia and vast number of people who have schizophrenia have not got schizophrenia because of their cannabis consumption (Degenhardt et al, 2004).


    Cannabis consumption may affect small percentage of population that is vulnerable socially and mentally. The pattern of cannabis use leading to clinically significant impairment or distress has manifested by a need for increased amounts of the substance to achieve intoxication or desired effect. That effect is then reduced by continuous use of the same amount of substance. Individuals then consume larger amount of substance to achieve that similar feeling and these persistent efforts start to affect the psyche of the individuals. Schizophrenia is more prevalent in individuals with poor socio economic background and history of substance abuse. Cannabis causes changes in neurotransmitter systems that make depressed mood more likely but greater evidence supports that this problem is due to individual behaviour pattern. Evidence from both hypotheses is limited and there needs to be well designed longitudinal studies including studies that examine cannabis use on older Australians to further narrow the relation between cannabis use and schizophrenia (Degenhardt et al, 2004).

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  1. derpahderp
    Cannabis May Cause Schizophrenia-Like Brain Changes
    By Jane Collingwood

    Researchers looking at the effects of cannabis on the brain have made some interesting discoveries. The effect is similar to some of the symptoms of schizophrenia, say Dr. Matthew Jones and colleagues at Bristol University, UK. They predicted that the detrimental impact of cannabis on memory and cognition might be caused by brain networks being “disorchestrated.”

    Normally, specific parts of the brain are tuned into each another at certain frequencies, say the researchers. This rhythmic activity produces brain waves and allows information to be processed in order for us to react.

    The team used the analogy of an orchestra to explain how this works. They say that brain activity can be compared to the performance of an orchestra in which string, brass, woodwind and percussion sections are joined together in rhythms dictated by the conductor. In a similar way, specific structures in the brain tune in to one another at certain frequencies. Their rhythmic activity creates brain waves, and the tuning of these brain waves normally allows information to be processed that guides our behavior. But cannabis causes disturbances in systems involved in concentration and memory, the team found.

    The primary psychoactive ingredient of cannabis, known as THC, activates cannabinoid receptors, which are found in many brain areas. In the research, the team measured the electrical activity from hundreds of neurons in rats when given a drug similar to THC which also stimulates cannabinoid receptors.

    This showed that the effects on individual brain regions were subtle, but brain waves across the hippocampus and prefrontal cortex were completely disrupted. These two brain areas are vital for memory and decision-making, so the rats were no longer able to accurately navigate a maze. Both areas are also involved in schizophrenia.

    Findings are published in the Journal of Neuroscience. The authors write that these results show a possible mechanism behind the cognitive impairment caused by cannabis that was described by Dr Frederick T. Melges and his team back in 1970. Dr. Melges called the effect “temporal disintegration,” and described it as “difficulty in retaining, coordinating and serially indexing those memories, perceptions and expectations that are relevant to the goal one is pursuing.”

    More recent studies suggest that THC given intravenously to healthy volunteers can induce several psychotic symptoms of schizophrenia, so the authors believe that THC studies be used to model broader aspects of the disease, not just cognitive dysfunction.

    Dr. Jones commented, “Marijuana abuse is common among sufferers of schizophrenia and recent studies have shown that the psychoactive ingredient of marijuana can induce some symptoms of schizophrenia in healthy volunteers. These findings are therefore important for our understanding of psychiatric diseases, which may arise as a consequence of ‘disorchestrated brains’ and could be treated by re-tuning brain activity.”

    Co-author Michal Kucewicz added, “These results are an important step forward in our understanding of how rhythmic activity in the brain underlies thought processes in health and disease.”

    The researchers conclude, “These tools will continue to shed light on the neural mechanisms of working memory and decision making in health and disease.”

    A 2012 review of current knowledge shows that the endocannabinoid system in the brain has a major role in schizophrenia. “Data reported so far clearly indicate the presence of a dysregulation in the endocannabinoid system in animal models of psychosis as well as in schizophrenic patients,” the review says.

    Its authors, led by Professor Daniela Parolaro of the University of Insubria, Italy, add that animal models suggest that adolescence is “a highly vulnerable age for the consequences of cannabis exposure on different domains (such as cognition and social behavior) that are altered in psychotic disorders.”

    They suggest that drugs which target the cannabinoid system are “a new therapeutic possibility for psychotic disorders.” However, they warn that drug studies so far have not had straightforward results, with different types of drug showing different effects.

    But despite all these limitations, cannabidiol, a compound found in cannabis that activates cannabinoid receptors, has shown fairly consistent antipsychotic properties in animal tests. Recent studies indicate that cannabidiol may be as effective as antipsychotics in treating schizophrenia.

    The benefit of cannabidiol appears similar to that gained from atypical antipsychotic drugs, and so far it is considered a safe and well-tolerated compound. Future studies will need to compare its antipsychotic effects against standard drugs for schizophrenic patients.


    Kucewicz, M. T. et al. Dysfunctional Prefrontal Cortical Network Activity and Interactions following Cannabinoid Receptor Activation. Journal of Neuroscience, published online October 25, 2011.

    Zamberletti, E., Rubino, T. and Parolaro, D. The endocannabinoid system and schizophrenia: integration of evidence. Current Pharmaceutical Design, published online June 7, 2012.

  2. derpahderp
    Marijuana and Schizophrenia

    by Natasha Tracy

    The link between marijuana and schizophrenia or psychosis has been identified for a long time. Many research studies have shown that those who have used cannabis have a greater than average chance of having schizophrenia. What’s more, the more marijuana the person is exposed to, and the younger the exposure, the greater their risk of schizophrenia seems to be. Marijuana users may also develop schizophrenia, on average, two years sooner than non-users.

    However, while this link is known, the causes of the link are not. Researchers aren’t sure if cannabis and schizophrenia are linked because the cannabis itself is increasing the risk of schizophrenia or because those with schizophrenia are predisposed to using cannabis (see Schizophrenia and Substance Abuse).

    Marijuana and Psychosis

    A major component of schizophrenia is psychosis, and it’s thought that marijuana may be able to induce or exacerbate psychosis. In fact, the latest version of the Diagnostic and Statistical Manual of Mental Disorders (DSM-IV-TR) recognizes a form of psychotic disorder specifically induced by weed. Cannabis-induced psychotic disorder may occur with delusions or hallucinations just as the psychosis found in schizophrenia. 1

    This also means that people with schizophrenia, who already experience psychosis, should stay away from weed as it may worsen their symptoms.

    Cannabis Use and Schizophrenia

    In several studies, cannabis use and schizophrenia have been linked. Repeatedly, research has found that those who smoke cannabis are twice as likely to develop schizophrenia versus non-smokers. In addition, those with schizophrenia are more than twice as likely to smoke pot as opposed to those who are not schizophrenic.

    There are many possible reasons for this connection. One is that schizophrenics may find marijuana more appealing than those without the disease. In fact, those with schizophrenia report feeling happier than those who use marijuana but are not schizophrenic. People with schizophrenia using cannabis also report a reduction in negative feelings, less anxiety and less social withdrawal. In spite of the fact that using marijuana may increase the hallucinations in this group, the positives are often seen to outweigh the negatives. Unfortunately, this leads to a high rate of addiction to marijuana for schizophrenics.2

    Can Marijuana Cause Schizophrenia?

    While many studies have been done looking at the use of weed and schizophrenia, a causal relationship cannot be established. Right now, the best guess of researchers is that for those with biological risk factors, using cannabis does, indeed, increase the risk of schizophrenia. For those with no pre-existing risk, marijuana may not increase their risk of developing schizophrenia. In short, more research is needed before an evidence-based understanding of the link between schizophrenia and marijuana is possible.

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