Introduction
Cannabis is also known as weed, hashish and a large wide variety of different slang phrases. The most common form is marijuana – a “greenish-grey mixture of the dried flowers of Cannabis sativa” (NIDA 2018, para. ). In terms of intake, some individuals smoke marijuana in pipes, hand-rolled cigarettes or in blunts. The predominant mind-altering chemical in cannabis that is accountable for most of the intoxicating effects in people is known as delta-9-tetrahydrocannabinol (THC).
Cannabis is the most commonly used psychoactive drug around the world after alcohol and the first among illicit substances. During the last several years, the number of cannabis users has increased among adolescents and concerns have been raised that its consumption can lead to serious mental disorders specifically psychotic disorders. Nemours research studies have been conducted to investigate the link between cannabis use and schizophrenia. These studies aim to explore the adverse consequences of cannabis use together with whether it increases the risk of developing schizophrenia.
The available evidence in the literature shows a connection between cannabis and psychosis. Seven years ago, the Swedish Conscripts Cohort was the only major study control that addressed this topic. New studies have emerged and supported the Swedish study that cannabis is a substantial association factor for schizophrenia. However, other studies are more careful when drawing such conclusions and interpretations because there is no clear evidence that cannabis causes schizophrenia.
Regarding this assignment, I am going to address the importance of this topic in the field of addiction and healthcare, assessing the research that suggests that cannabis plays a role in schizophrenia and the strengths and weakness of the study. Lastly, I will conclude the research with possible academic suggestions for the literature review.
Rationale for the Subject and its Importance in the Field of Addiction and Healthcare
The relationship between cannabis use and psychiatric disorders is a complicated public health issue. According to the World Drug Report (2019), “UNODC estimates that roughly 3.8 per cent (range: 3.3–4.4 per cent) of the global population aged 15–64 years used cannabis at least once in 2017, the equivalent of some 188 million people (range: 164–219 million)” (p.). These statistics highlight the importance of conducting a multidisciplinary study to come up with effective prevention programs and enhance protective factors, which will ultimately improve population health. In addition, it is important to consider the effects of second-hand exposure to cannabis smoke.
This assertion holds because the harmful effects of passive smoking are known but there is not enough evidence about whether passive cannabis smoking presents similar health risks. Currently, very few researches have been conducted on the probable psychoactive effect of exposure to second hand cannabis smoke.
Structured Critical Review
Despite the several lines of evidence proposing a connection between cannabis and psychosis, the Swedish Conscripts Cohort was the only major study control that addressed this topic. The research, “Cannabis, Schizophrenia and other Psychoses: Longitudinal Studies on Swedish Conscripts”, by Manrique-Garcia (2014) explored how cannabis can increase the risk for psychiatric disorders such as psychosis and depression, and especially schizophrenia. The study’s objectives were to determine the long-term risk of developing schizophrenia and the risk of depression among cannabis users and non-users. It also sought to assess and compare the prognosis of schizophrenia among patients with a history of cannabis use and those without. The other objective was to assess mortality rates among cannabis users as compared to non-users to establish whether cannabis increases the risk of death among patients with psychotic disorders.
The article’s title is clear, and it is related to the specified paperwork. The abstract is intelligible as the author identifies the aims of the study and describes the objectives, methods and results obtained. The introduction is not stated clearly, and thus it is difficult to locate as it is merged with the background information. However, the author indicates why the research was undertaken and the background section is rich as it provides sufficient information to understand the goals of the study.
According to the literature review given in the article, the relationship between cannabis use and schizophrenia is complicated because different people will be affected in different ways. However, the overall effects of cannabis on the brain are mild euphoria, perceptual alterations, and relaxation. The neurobiology of marijuana underscores what happens to the brain once the substance is introduced to the body system.
The effects of THC are mediated through cannabinoid receptors type 1 (CB1), which are mainly found in the brain where they suppress inhibitory or excitatory synaptic transmission. Therefore, continued exposure to marijuana, especially during adolescence and young adulthood, could lead to impaired neural connectivity (Manrique-Garcia 2014). It could also cause a permanent alteration of dopamine, glutamate, and GABAergic systems, and these effects underscore the link between cannabis and psychosis. The author used 109 reference materials throughout the paper to support all the claims made.
According to the article, over 200 million people around the globe use marijuana with the peak prevalence age being between 20 and 24 years. In 2010, over 2 million people lived with cannabis-related disabilities due to dependence. In terms of gender, males are more likely to use cannabis as compared to their female counterparts, and the lifetime risk of dependence is about 9 per cent. The United States, Australia, France, and Spain are some of the leading countries with the highest burden of cannabis dependence.
The study used a quantitative approach to assess the association between cannabis and schizophrenia. Quantitative research is more structured than qualitative research, and it is used to measure a problem by generating numerical statistics, which could be converted to usable data. The study sample involved 50,087 Swedish military conscripts and the cohort was followed from 1969/1970 to 2007. Cannabis users were taken as cases while non-users were used as controls. Risk factors were well defined, as primary outcomes, and they included risk of schizophrenia, depression, death among people with psychosis, and death among the total cohort.
The author gathered information about potential covariates based on prior studies to avoid confounding factors. The covariates included contact with juvenile authorities, run away from home, truancy, smoking, solvent abuse, risky use of alcohol, psychiatric diagnosis at conscription, divorced parents, use of intravenous drugs and other substances at conscription, IQ score, upbringing, family socioeconomic status, and the civil status during the follow-up. The confounding factors were controlled to avoid biased results. Reliability of the study was improved by using reputable databases for data collection. The conscripts were followed up for 30 years to examine their behaviors as related to the study variables.
The study’s analysis was not an intention-to-treat. On the contrary, the different statistical analyses were carried out to assess the various risk factors for depression, mortality rate, schizophrenia and other psychotic disorders among cannabis users and non-users. For instance, Cox proportional hazards modeling assessed the risk of developing depression and death among marijuana users at conscription. Negative binomial regression estimated prognosis rate ratios with 95% confidence levels. Logistic and multinomial logistic regression calculated odd ratios for developing schizophrenia with 95% confidence intervals.
Fisher’s exact test was used to test differences in the type of schizophrenia at first admission and pre-morbid psychiatric diagnosis. Ultimately, the results were adjusted for confounding factors. Permission to extract data from the conscription database was sought and granted by the Stockholm Regional Ethical Review Board. The obtained data were treated based on recommendations by the Swedish Data Inspection Board.
The results obtained from this study indicated a strong correlation between cannabis use and the risk of developing schizophrenia. Therefore, cannabis users were more likely to develop this psychiatric condition as compared to non-users. After controlling confounding factors, specifically disturbed childhood, cannabis users did not have an increased risk of developing depression. However, patients with schizophrenia and a history of cannabis use higher chances of readmission and longer hospital stay duration as compared to those without such history. Additionally, study participants with a history of heavy cannabis usage had higher mortality rates as compared with non-users. However, having a history of cannabis use was not a contributing factor to death rates among psychotic patients.
These results underscore the importance of studying this topic because the currently available literature is divided on whether cannabis use is linked with the possibility of developing schizophrenia. The discussion part of the paper is consistent with the results, and the author is critical to himself and other research works on the subject. The study’s strengths and limitations have also been mentioned.
Strengths and Weaknesses of the Undertaken Literature Review
The author used 109 reference materials to compile to back claims made throughout the article. The references had several strengths and weaknesses alike. Some of the strengths included the use of up-to-date information. Given that the article was written in 2014, materials published after 2009 would be considered as current literature, and the majority of the references used in this article fall within this timeline. In addition, the references are relevant to the study.
The Swedish conscript survey one of the reputable cohort studies on the issue of cannabis use and schizophrenia given that it used a large sample size (50,087 participants) followed for 30 years. As such, the results from this study have a scientific basis for generalization in other set-ups. Additionally, the study assessed schizophrenia as a specific outcome, which gives it enough power to assess the study’s objectives. The homogenous nature of the study population allowed for the lifetime prognosis of schizophrenia based on background factors.
However, the review has several limitations. First, the available baseline data on cannabis use was only after conscription and thus other risk factors after baseline might influence the ultimate results. Second, only males were used in this study, and thus effects on females were not captured. Third, information on hereditary factors was lacking during the assessment. Fourth, cases of schizophrenia and other psychotic disorders were only limited to in-patient care. Therefore, milder forms that do not require hospitalization were not factored in this study. Consequently, further research is needed to fill the gaps exposed in this study.
Possible Practical or Academic Implications for the Review
The implications for this review and the results from this study are multi-pronged. These findings could shape the political and ideological debate on the issue of regulating cannabis. In public health policy, the link between cannabis use and schizophrenia and other psychotic disorders should be understood in context before liberalizing laws on marijuana. According to the literature reviewed in this paper, eliminating the usage of any form of cannabis would reduce schizophrenia incidences by over 10 per cent. In addition, the usage of cannabis is expected to introduce 10 % of new cases of schizophrenia.
Therefore, with the increasing demands to decriminalize marijuana use, it could be hypothesized that consumption in the public will increase steadily. This aspect underscores the need for academicians to invest time and resources to research more on the effects of such changes in relation to psychotic disorders. Additionally, cannabis has also been shown to have positive therapeutic uses, and such conflicting information could affect policy-making. Further research is needed to identify the point at which marijuana health burdens overweight the associated benefits for evidence-based decision-making.
Summary/Conclusion
The topic of cannabis use is controversial with proponents citing its benefits and calling for the liberalization of laws governing marijuana. Opponents of this issue are concerned with the negative effects of cannabis use, especially its link to psychotic disorders, such as schizophrenia. This controversy underlines the need to have a comprehensive study on the benefits and health concerns associated with marijuana. “Cannabis, Schizophrenia and other Psychoses: Longitudinal Studies on Swedish Conscripts”, by Manrique-Garcia (2014) was reviewed for this assignment. The author sought to establish the relationship between cannabis use and schizophrenia and other psychotic conditions among other objectives. A Swedish cohort of 50,087 military draftees was used for the study. The subjects were followed for 36 years from 1969 to 2007.
After controlling for confounding factors, the results showed that cannabis use increases the chances of developing schizophrenia and other related disorders. These findings are important as they could be considered when making policies on the liberalization of marijuana use. In academics, the research gaps highlighted in this review present an opportunity to investigate this topic more to derive reliable results for informed decision-making.
References
Manrique-Garcia, E 2014, ‘Cannabis, schizophrenia and other psychoses longitudinal studies on Swedish conscripts’, MSc. Thesis, Karolinska Institutet, Stockholm.