June 2010


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By Dr. Sandra Reid

By whatever name—ganja, marijuana, weed—smoking cannabis sativa is illegal in Trinidad and Tobago. Classified as a dangerous drug, marijuana is included in the First Schedule list of narcotic drugs. Under the Dangerous Drugs Act, possession of any quantity is an offence liable upon summary conviction to a fine of $25,000 and to imprisonment for five years; and upon conviction on indictment to a fine of $50,000 and to imprisonment for between five and ten years.

Marijuana users experience the mind-altering effects of tetra hydrocannabinol (THC), the active chemical found in the cannabis sativa plant. Reports describe sedation, euphoria and heightened perceptions. The psychoactive effects of THC are not neatly classified though, and include hallucinogenic, stimulant and depressant actions.

Many consider the Act too punitive, arguing that it subjects ordinary people to criminal punishment for innocuous behaviour. Their argument is that maintaining the classification of marijuana as an illegal drug may result in unnecessary incarceration resulting in a permanent legal record, especially harsh for young people who may run afoul of the law during a period of short-lived experimentation. To them, this wastes valuable law enforcement resources, which at the extreme are expended in the unsuccessful war to eradicate the production of marijuana and dry up the supply of the drug. Dissenters suggest that the criminalization of marijuana deprives people of its ascribed medicinal benefits.

Decriminalization of marijuana use would entail the removal of prohibitions on the possession of small, specified quantities of the drug for personal use. Decriminalization may also be restricted to the use of specific amounts for medicinal purposes only. Legalization of marijuana use goes further and calls for the legal distribution of the drug, which then becomes as readily available as alcohol or cigarettes.

A recommendation for the decriminalization of marijuana begs the question – will the ills of strict prohibitions be replaced by the harm of increased use?

Rigorously conducted medical research has confirmed a number of adverse health effects as a result of regular marijuana use. Higher rates of chronic lung disease, respiratory infections and pre-cancerous changes in the lungs occur in smokers of marijuana. A June 2009 study from the University of Leicester (reported in the journal Chemical Research in Toxicology) suggested that marijuana smoke may be as harmful, or perhaps even more toxic, than tobacco smoke. Smoking three to four marijuana cigarettes a day was reported to cause as much airway damage as smoking 20 or more cigarettes a day. Another recent report from the Fred Hutchinson Cancer Research Center in Seattle linked marijuana use to testicular cancer, especially among those who began smoking before the age of 18.

“Just being a marijuana smoker seemed to carry a 70% extra risk, while those who smoked it regularly, or had smoked from an early age, had twice the risk compared to those who had never smoked it,” stated the report.

Harvard University researchers in March 2000 reported that the risk of a heart attack is five times higher than usual in the hour after smoking marijuana, (http://www.news.harvard.edu/gazette/2000/03.02/marijuana.html) while a Columbia University study (1999) found that a control group smoking a single marijuana cigarette every other day for a year had a white blood cell count that was 39% lower than normal, evidence of a damaged immune system which would make the user more susceptible to infection.

Surveys of driving under the influence of marijuana indicate a greater risk of accidents for users, as well as a greater risk of fatality. The presence of measurable levels of THC in the blood of drivers involved in motor vehicle accidents, in the absence of alcohol or other drugs has established marijuana intoxication in a causal role. This is consistent with documented short-term effects of marijuana use, which include distorted perception, loss of motor skills, trouble with thinking and problem solving, and decrease in muscle strength.

By far the biggest adverse consequences of regular marijuana use are the mental health consequences. Marijuana affects thoughts, perceptions, and information processing. Persons under its influence display diminished capacity to learn and recall new information. However, there is no definitive evidence that heavy long-term marijuana use permanently impairs memory or other cognitive functions.

The risk of addiction to marijuana is relatively low compared with other psychoactive drugs but the reality of marijuana addiction is scientifically supported by the occurrence of loss of control over use, tolerance to the psychoactive effects, associated hazardous outcomes associated with use and the occurrence of withdrawal symptoms, most commonly irritability, sleep disturbance, nausea and anxiety, on stopping or reducing use.

Studies consistently show an association between chronic marijuana use and the development of marijuana psychosis, depression, bipolar disorder and panic attacks. The link between marijuana use and schizophrenia has been documented in many scientific studies. A 2002 report in the British Medical Journal, among 50,000 members of the Swedish army, found that heavy consumers of marijuana at age 18 were over 600% more likely to be diagnosed with schizophrenia over the next 15 years than those who had not smoked. It is estimated that between 8% and 13% of all cases of schizophrenia are linked to marijuana/marijuana use during teen years. The risk is particularly great among those young people who possess a genetic high risk (positive family history) for schizophrenia.

While the adverse effects of marijuana have been scientifically established, there is less evidence to support the medicinal value of smoked marijuana. Anecdotal reports abound on its effectiveness in reducing the nausea induced by cancer chemotherapy, stimulating appetite in AIDS patients, reducing intraocular pressure in people with glaucoma, relieving pain, and reducing muscle spasticity in patients with neurological disorders. Anxiolytic, antipsychotic, antispasmodic, antiemetic, antiepileptic, antioxidant, analgesic and anti-tumor properties have all been reported but mostly relate to the use of synthetic cannabinoids or marijuana-based medicinal extracts. These studies for the most part do not assess smoked marijuana, have failed to compare marijuana with alternatives or viable treatments, and claims of therapeutic effectiveness are not based on the results of controlled scientific studies. Following a comprehensive study (Marijuana and Medicine: Assessing the Science Base, 1999), the Institute of Medicine acknowledged the potential therapeutic value of cannabinoid drugs but found little reason to recommend crude marijuana as a medicine, particularly when smoked, since smoking created risks that would not exist from other forms of delivery. They concluded that the active ingredients in marijuana could be developed into a variety of promising pharmaceuticals and recommended that research continue to look at the efficacy of THC for medicinal purposes. Such research has determined that dronabinol (Marinol) is a safe and effective treatment for nausea and vomiting associated with cancer chemotherapy, and a treatment of weight loss in patients with AIDS. Marinol is a synthetic THC drug which does not produce the harmful health effects associated with smoking marijuana. Initial enthusiasm for THC as an antiemetic or to reduce intraocular pressure has waned with the advent of new medications that provide superior medical benefits with fewer adverse effects. Do the potential benefits of legalizing or decriminalizing marijuana for medicinal use outweigh the risk of increased use in the society?

-Dr Sandra Reid lectures in Psychiatry at the School of Medical Sciences, Faculty of Medical Sciences, UWI, St Augustine Campus.