Cannabis as medicine has come a long way in New Zealand since the scheme began in April 2020. There are now more products than ever available to be prescribed and many more people taking them. Uses include alleviating chronic pain, supporting palliative care, treating mental health issues and managing epilepsy or multiple sclerosis.
The two main cannabinoids used in treatments currently are CBD (cannabidiol) and THC (tetrahydrocannabinol). Since the cannabis plant produces at least 100 similar substances, there is scope for further benefits to be discovered.
Pharmacologist Jonathon Arnold at the University of Sydney is engaged in science to unlock the plant’s medicinal potential. He works at the Lambert Initiative for Cannabinoid Therapeutics, which was established in 2015 following a A$33.7 million (NZ$38m) donation from multimillionaire financial advisor Barry Lambert and his wife Joy, whose granddaughter Katelyn suffers from a debilitating form of childhood epilepsy.
“Our remit has been to look at all these different cannabinoids to see if any of them can be developed into safe and effective therapeutics for a broad range ofchronic illnesses,” says Arnold.
Insomnia is one area of interest. Over the years, Arnold has come across lots of anecdotal evidence that people who use very well-aged cannabis become sleepy. “But no one had ever put it to the test in a scientific way.”
Aged cannabis has high levels of cannabinol (CBN) which is converted over time from the plant’s main intoxicating ingredient, THC, as it breaks down. Arnold and his team ran a trial where they gave rats purified CBN and monitored the different stages of their sleep using polysomnography to measure brainwaves.
Taking CBN increased both non-rapid eye movement ‒ the deep sleep that promotes repair and recovery ‒ and rapid eye movement (REM), the stage of sleep where most dreams happen. The rats also had an increase in total sleep time.
One theory is that the chemical is working on the body’s endocannabinoid system, which regulates many bodily functions, including sleep. However, the researchers found that it wasn’t the CBN itself that had a significant effect on the cannabinoid receptor but a molecule the body makes when it is metabolised.
None of the rats in the study showed signs of the treatment being significantly psychoactive. “THC causes a reliable drop in body temperature; it makes the rats hypothermic,” says Arnold. “But with this, there was only a very subtle reduction in temperature. Also, when rats are under the influence of cannabis, it’s pretty obvious. They sort of lie down flat and don’t move.”
For a further, yet to be published, study, CBN was given to people with insomnia.
“At the doses we tested, there weren’t any clear signs of intoxication and the results were quite promising. It seemed to make them go to sleep more quickly and increase some of the non-REM sleep.”
In the US, CBN products are already being marketed for sleep, in forms such as tinctures, capsules and gummies. They sometimes also include melatonin, a hormone that plays a role in sleep.
While sleep continues to be an interest, much of Arnold’s research at the Lambert Initiative is focused on epilepsy and identifying cannabinoids with anti-convulsant effects.
He has been working with a molecule called CBGA (cannabigerolic acid), which has been shown to reduce seizures in mice that have a severe form of epilepsy called Dravet syndrome.
He is also investigating CBD as a treatment for the eating disorder anorexia nervosa and for addiction, PTSD, neuropathic pain and cancer. Plus, he is interested in the anti-inflammatory effects of cannabinoids and their potential as a longevity medicine.
“We’re really only at the very beginning with that but we’re seeing some interesting things.”
Already, he believes there is strong evidence for CBD as a treatment for epilepsy and multiple sclerosis, and fairly good evidence for cannabis having a role in pain relief. And CBN seems to have the best effects for sleep.
“But overall, there’s a lot more work that needs to be done to have the level of evidence required for a conventional medicine, particularly as there is such a variety of products that are administered in different ways.”
