By Ross Walker

In Australia over the past few years, there has been increasing debate about the potential health benefits of medical cannabis. This was highlighted by three very important examples demonstrating significant benefits.

The first was the case of Dan Haslam, the young man who died of bowel cancer in his 20s. His mother, Lucy, has become a very active campaigner for the widespread use of medical cannabis for a variety of conditions, because cannabis was the only treatment that relieved his suffering, from not just his condition, but also the treatment. The second example was the 60 Minutes program Charlotte’s Web, which highlighted the case of a young girl with severe refractory epilepsy caused by a rare condition, Dravet’s syndrome. Medical cannabis stopped her severe recurrent fitting. The third high profile case was that of Barry and Joy Lambert’s granddaughter who also suffers Dravet’s syndrome. Since commencing medical cannabis 18 months ago, she has had no further seizures.

Although there are no large, long-term randomised controlled trials of medical cannabis for a variety of conditions, there is growing scientific evidence for the benefits of medical cannabis for many cases of refractory epilepsy, especially in children.

There is also increasing work for a variety of aspects of cancer management, such as nausea and vomiting induced by chemotherapy, cancer pain and, potentially, reduction in cancer growth and spread.

There’s also some good work for medical cannabis relieving the spasticity of multiple sclerosis, with some early potential studies suggesting benefits for Alzheimer’s disease, Parkinson’s disease, a number of autoimmune diseases including lupus, rheumatoid arthritis and psoriasis, osteoporosis and a number of mental health issues.

But, this does not give a clean bill of health to the smoking of illegal, so-called recreational marijuana which is a completely different form of cannabis – which in my view should stay illegal.

Over the years, a large body of evidence has accrued suggesting the smoking of illegal marijuana may lead to mental health issues, predisposition to dementia, and possibly even cardiac rhythm disorders. There’s also evidence to suggest hormonal abnormalities, affecting a variety of endocrine glands such as the pituitary, adrenals and sex glands.

Although there are 100s of cannabinoid compounds that occur in a cannabis plant, there are two well known cannabinoid receptors in the body. The first is CB1 and the second, logically CB2. CB1 is basically found in the brain and nerves, whereas CB 2 is more a regulator of the immune system and gastrointestinal tract.

Recent research has demonstrated that CB1 is located in the mitochondria of nerve cells. The mitochondria are the fuel packs of the cells as they convert nutrients and oxygen into the energy or fuel that the cell needs to function. The activation of CB1 receptors within the mitochondria leads to damage to the nerves, with memory loss through reduced production of energy within nerves.

Another recent study also demonstrated that individuals who smoked illegal marijuana had a marked reduction in blood flow to nearly all areas of the brain, especially the hippocampus (which had the largest reduction in flow).

The hippocampus is the brain region associated with learning and memory and is also the first region affected in patients with Alzheimer’s disease. The researchers use the technique known as SPECT to accurately measure the blood flow within the brain. They examined just under 1000 individuals who had been diagnosed with marijuana use disorder and compared this with 92 controls who did not smoke marijuana. The SPECT study, which is a specific form of CT scanning, measures blood flow and activity during a mental concentration task. Clearly, the combination of a direct effect on the CB1 receptors in the mitochondria of nerve cells, coupled with reduction in blood flow, is a very cogent explanation as to why high concentration THC may lead to Alzheimer’s disease in regular users of marijuana.

In another blow for people who believe recreational marijuana use is of no concern, it has also been shown that high concentration THC (as found in the modern marijuana joint) can have a direct effect on dopamine levels which is the key chemical in the brain’s pleasure-reward system. Dopamine plays a key role in many aspects of brain function, including learning, movement, motivation, emotion and reward. It appears that the chronic ingestion of marijuana can significantly lower the levels of dopamine within the brain which has been associated with changes in mood, depression, lack of motivation, fatigue and associated with a number of other disorders such as Parkinson’s disease and ADHD.

Long-term marijuana use is associated with the number of mental health conditions such as depression, anxiety and even schizophrenia, and again, this may be related to low dopamine levels, not to mention the previously stated reductions in blood flow and effects on the fuel packs in the cells (the mitochondria).

Although I am a great supporter of the introduction of medical cannabis for specific health conditions, the overwhelming evidence for the detrimental effects of recreational, illegal marijuana places this drug in an entirely different category.

It is vital that the public understands the incredible difference between smoked, illegal marijuana and what may well be one of the next big things in medicine, medical cannabis.