How dangerous is cannabis?

Since the Constitutional Court’s ruling last year relating to private personal consumption of cannabis, there has been increased interest in the potential health implications of using the plant.

Few healthcare professionals have, however, explored how the compounds within cannabis affect the human body, said the

Akeso Group. Akeso is a group of private in-patient psychiatric hospitals, and is part of the Netcare Group.

“Cannabis has been used by humans for centuries for various neuropsychiatric conditions including pain and seizure disorders. By the late 19th and early 20th centuries, cannabis-containing medicines were commonly used by physicians for indications similar to the effects for which the plant is being investigated today,” said Dr Louis Roos, a psychiatrist practising at Akeso Arcadia, part of the Akeso network of psychiatric hospitals offering treatment for addiction disorders and mental health concerns.

“During the 20th century, scientific study of cannabis was limited due to its illegal status in many countries, however recent decades have seen major breakthroughs in our understanding of the drug. While research into potential medicinal effects is still in its infancy, we are starting to understand how it interacts with the brain and may influence certain mental and physiological processes,” he said.

“The question may be asked, ‘on a scale of one to 10, how dangerous is cannabis?’ However, there is unfortunately no simple answer, as there are many complex factors and finer nuances to be considered.

“There is still a blind belief by many members of the public that cannabis could be a cure-all treatment for various conditions with no harmful effects, however the evidence simply does not support this. Cannabis contains more than 500 active components and, while it is possible that some may have medicinal potential, we are only in the very early stages of developing an understanding of the ratios and concentrations of these compounds that could have either positive or negative outcomes for various conditions.

“Nonetheless, I would encourage healthcare professionals to acquaint themselves with the available research in order to cultivate a better informed, more nuanced understanding of cannabis, even though doctors cannot yet prescribe cannabis as treatment for any condition.”

Dr Roos pointed out that for any cannabis-containing product to be sold or marketed as medicine in this country, it would first need to go through a lengthy process to be registered with the South African Health Products Regulatory Authority.

“While certain products have been registered with the relevant health authorities in other countries, at this stage no cannabis products are registered for use in South Africa.”

• Addiction risk

Cannabis has been labelled as a “gateway drug” with evidence that it primes the brain for a heightened response to other drugs, however Dr Roos pointed out that this also holds true for both alcohol and nicotine.

“Adolescents in particular should not use cannabis, as there is a much higher risk of addiction in younger people. Approximately nine per cent of cannabis users become dependent on the drug, however the dependency rate tends to be higher among people who start using cannabis at a younger age. To put this in context, a lifetime risk of dependence is as high as 15 per cent for alcohol and 32 per cent for nicotine users.”

• Health risks of smoking cannabis

“There are potential health risks to using cannabis that people should be aware of. People may be tempted to experiment with cannabis based on a common, though incorrect, perception that it is safe for everyone. The available scientific information suggests there are potential risks that warrant careful consideration.

“Using cannabis regularly can have detrimental effects on the stability of a multitude of psychiatric disorders, including mood disorders, such as depression and bipolar disorder, anxiety and psychotic disorders.”

Dr Roos said significant evidence suggested a link between schizophrenia and cannabis use, however a causal link has not been definitively established. It has been suggested that cannabis use may act as a trigger for schizophrenia in predisposed individuals, thereby resulting in an earlier age of onset of schizophrenia.

He added that long-term heavy use of cannabis is associated with amotivational syndrome, which is described as a sense of apathy, poor concentration and a lack of motivation for work, social and other activities.

“It should be noted that cannabis intoxication significantly impairs driving ability.”

Dr Roos warned that the risk of being involved in a vehicle accident is doubled soon after a driver has used cannabis. The risk is compounded when alcohol and cannabis are used together.

Long-term cannabis smoking has been associated with the development of lung and testicular cancer, however Dr Roos pointed out that there is weak evidence to suggest a direct causal link. It should also be noted that smoking cannabis over the long-term may predispose individuals to chronic airway conditions and may increase the risk for certain vascular conditions.

He explained that the endocannabinoid system, which is a system of cannabinoid receptors in the body and central nervous system, is involved in multiple processes of brain development.

• Potential benefits

Dr Roos said preclinical evidence suggested that Cannabidiol (CBD) – which is a component of cannabis that does not contribute to the cannabis “high” – as Tetrahydrocannabinol (THC) – the main psychoactive cannabinoid and is responsible for the “high” for which recreational users use cannabis – could potentially prove helpful for multiple anxiety disorders, including post-traumatic stress disorder (PTSD), generalised anxiety disorder, panic disorder, obsessive compulsive disorder and social anxiety disorder.

“More research is needed on the effects in individuals with existing anxiety disorders, and long-term efficacy has yet to be established.”

He said several small studies in humans with psychosis, which is defined as a mental state in which an individual loses touch with reality and may experience delusions or hallucinations, have reported CBD could potentially offer some benefit for reducing psychotic symptoms, however more extensive and rigorous studies are needed before any solid conclusions can be reached.

“The effectiveness of medical cannabis as a treatment for epilepsy remains in question, and the mechanisms involved are little understood. In some countries, however, a CBD-containing drug manufactured by a British company has been registered for Dravet syndrome, which is characterised by intractable seizures in children.

“It has been hypothesised that an interplay between anti-seizure activity and anti-inflammatory properties of cannabis could account for the effectiveness observed in some patients. Studies in animals show CBD to have anticonvulsant properties, however in certain individuals THC, which is the compound responsible for the ‘high’ feeling, can trigger seizures,” Dr Roos added.

He said certain symptoms of multiple sclerosis, a neurological disease, may be improved through cannabis use.

“Muscle spasticity, spasms, neuropathic pain and bladder dysfunction may be alleviated, while some patients also report improvement in fatigue and reduction in sleep disturbance and dysaesthesia, which is discomfort associated with nerve damage,” he explained.