The lack of scientific evidence on the benefits of cannabis in the treatment of medical conditions have added to the complexities surrounding its use therapeutically, legally and socially.

In a Clinix Health Group and Health IQ Consulting-hosted webinar talk late last week – advertised as “Cannabis: a pragmatic approach for clinicians” but changed to “Cannabis for Agnostics” on the night – Lancet Laboratories chemical pathologist, Dr Ryan Benjamin, intimated that there were really “no short answers” clinicians could give to patients when questioned about cannabis use.

Common among these clinicians should anticipate, said Benjamin, included: Does cannabis cause cancer? Is it as bad as cigarettes? Is it good for asthma?

Others could be: “Will marijuana make my son stupid? Will he go mad? All the dagga rookers are thin, so will it help me lose weight?”

“Before giving this talk, to me cannabis was cannabis, but have since found out that the plant and everything about it is very complicated,” Benjamin noted, citing the cancer question as the first preponderance. If compared with cigarette smoking, considering the epidemiological evidence of cigarette smoking causing cancer and that many of the chemicals in cigarettes could be found in marijuana, then intuitively, he suggested, the answer would be “yes, it does cause cancer”.

But, he postulated, a marijuana user would smoke less joints than a 20-cigarette-a-day smoker and the cancer risk should be less:” But this hasn’t been scientifically demonstrated…!”

Is it good for asthma? While it has been said to cause dilation of the airways, again there was no clinical evidence: “In short, the normal bronchodilator pump has greater effect than dagga for asthma.”

Will marijuana make my son stupid?  “This is where it gets even more complicated with both the short and complicated answers being: we don’t know! Certainly many people who smoke marijuana chronically have lower IQs and lower ability to perform more complex tasks.

“Question that has to be asked here,” said Benjamin, “is whether it was these problems that made these people start taking marijuana as opposed to the effects of taking it – a matter of cause and effect.

“In short term use” Benjamin added, “there can be short term memory loss and with chronic use, reversible cognitive decline. Might be reversible in some cases, but time is lost in the process so the answer, once again, is complicated.”

Not as complicated, he continued, was the question of losing weight: “Marijuana itself does not cause weight loss, despite many smokers being thin which could be put down to their socio-economic circumstances.”

First among the Q&A was effects of combining alcohol with marijuana: “Alcohol has demonstrably more negative cognitive effects than cannabis. It seems that cannabis can cause cognitive effects but probably less than those of chronic alcohol abuse.

“But together they do act synergistically and the use of both therefore will cause greater harm.”

Most challenging and probably the most complex aspect surrounding cannabis, Benjamin concluded, was how to regulate the implementation of its use: “Don’t know how we are going to get around legalising cannabis. How do you define the cannabinoids legally when there are so many different modifications?

“How are we going to arrive at a legal definition?”

Picking up on the regulation challenges during question time, psychiatrist Dr Mashadi Motlana drew attention to the global impact of cannabis legalisation: “We have seen in the international literature the impact of the legalisation of cannabis. Parents are smoking it and  children are smoking with an increased incidence of pathology in young people and unfortunately, similarly an increased incidence of psychosis,” she said, agreeing that regulating the use of cannabis was going to be extremely difficult while expressing real concern about the long-term effects on the adolescent brain.