Evidence Re Cannabis, Mental Health and Psychosis 5.28. One of the repeated concerns about cannabis/ marijuana is its link to psychosis. Most of the reservations that were expressed about possible law reform involved this claim. Some respondents at the consultations feared that any change in current legislation could exacerbate mental health issues which current health and legal sectors are ill-equipped to effectively address. Given the clear link with the criminal justice system, that is, the fear that this could lead to criminal behaviour, this is an issue that must be confronted head on. 5.29. The Commission was mindful about these concerns which in the main came from nurses and other medical practitioners working in psychiatric spaces. However, the Consultations themselves revealed that there was no empirical data collected which could demonstrate whether cannabis caused psychosis, or whether persons who were already susceptible to psychosis and other mental disorders self-medicated with the use of cannabis/ marijuana given its well touted properties for stress relief. This was an issue that we The emerging consensus is that Marijuana were particularly eager to interrogate. The scientific use may advance the age of onset of evidence as it relates to marijuana use and psychosis thus psychosis, but only in high risk individuals far, is not conclusive.
such as those with a genetic vulnerability.
5.30. In regards to psychotic disorders such as schizophrenia, current theories suggest that the relationship could be due to several factors: (1) Self- Medication: Some individuals may use marijuana to self- medicate symptoms; (2) Precipitate: Problematic use of marijuana (heavy use, frequent use, high potency) in adolescents may advance the age of onset and increase the risk for the disorder in persons with a predisposition to such disorders (Arseneault et al 2004; Zammit et al, 2007); (3) Exacerbate: Marijuana use may worsen the symptoms of schizophrenia and Bipolar Disorder; and (4) Coexist: The high level of marijuana use among persons with psychotic disorders may be coincidental relationship rather than marijuana being the cause. (Degenhardt et al 2001, Ferdinand et al. 2005). 5.31. Overall, the emerging consensus is that marijuana use may advance the age of psychosis, but only in high risk individuals such as those with a genetic vulnerability. However, it is to be noted that many individuals with psychotic disorders do not report a history of marijuana use. Significantly, just concluded studies in Jamaica, evaluating results since the 2015 decriminalisation amendments, reveal no significant change to those reporting psychosis.118 5.32. Intriguingly, very recent data reveals evidence of the use of cannabis/ marijuana in the treatment of post-traumatic stress disorder (PTSD), research and treatment that is now being supported by the US government after much opposition.119 This appears to support those who have consistently maintained that the link between psychosis and cannabis/ marijuana is as a result of self-medication and that consequently, cannabis/ marijuana is not causative of psychosis or violence. 5.33. Withdrawal and Dependence Syndrome - Research has shown that marijuana use is associated with dependence, which is a proxy for addiction, intoxication and withdrawal. (American Psychiatric Association 2013). However, these categories of Dependence, Intoxication and Withdrawal Syndromes are not unique to marijuana and they are all described for the major drugs of abuse such as alcohol, nicotine, opiates and cocaine etc. (American Psychiatric Association, 2013). In fact, these symptoms with these conditions are less severe for marijuana as compared to other drugs (Smith 2002). The Dependence liability of marijuana compared to other drugs are: Marijuana is 10%, Nicotine 32%, Opiates 26%, 23% for alcohol, and 21% for cocaine.”120 5.34. Amotivational Syndrome - This is a syndrome described in users of marijuana, this syndrome has been refuted by several researchers some of whom posit that what is observed are depressive symptoms Abel and Mona - http://www.looptt.com/content/uwi-mona-psychiatrist-no-increase-cannabis-cases, ‘UWI Mona psychiatrist: No increase in cannabis cases’ – Caribbean News, May 14, 2018. 119 Robert Muller, ‘Medical Marijuana for PTSD? Combined with other therapies, medical marijuana may help those with PTSD.’ Psychology Today, Dec 14, 2017, https://www.psychologytoday.com/intl/blog/talking-about-trauma/201712/medical-marijuana-ptsd 120 Lopez-Quintero et al., 2011. Some report nicotine at 68%. This is a distinctive condition but it is mild, short lived and characterized by irritability, agitation, sleep disturbances and nausea. short lived disorder due to recent onset of Marijuana use. It is characterised by euphoria, impaired judgement, motor skills, red eyes, dry mouth, increased appetite and tachycardia. (American Psychiatric Association 2013). 118
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