Can cannabis alleviate the symptoms of Parkinson’s disease?

Parkinson's disease is a nervous system disorder that affects movement. Early in the disease, the first symptom is frequently an involuntary shaking of the hands. Symptoms worsen with time, hindering movement control. The disease is named after the doctor James Parkinson, who in 1817 published An Essay on the Shaking Palsy. The reason for the lack of movement control derives from a disturbance in the nervous system driven by the lack of dopamine in the nervous cells or neurones. The lack of mobility control leads mainly to tremors, muscle and joint rigidity, and lack of balance. Parkinson's is a degenerative disorder with no cure at present. According to the Spanish Parkinson's Disease Federation, once it emerges, it is persistent and worsens with time.

Scientists are now investigating how phytocannabinoids have an effect on the symptoms of Parkinson's patients. But so far there are only a few clinical studies proving the short to medium-term effectiveness of cannabis. To be able to reach significant conclusions, it is necessary to carry out trials involving a large number of patients, and this is proving difficult due to cannabis' illegal nature. Let's review some of these studies and look at what Javier Fernández Ruiz has to say regarding this. Mr Fernández Ruiz is a Professor at the Universidad Complutense de Madrid (UCM), where he leads a research team that studies the neuroprotective potential of cannabinoids in several chronic neurodegenerative diseases, in order to evaluate if cannabis can improve the quality of life of Parkinson's sufferers.

Neuroprotective properties of some phytocannabinoids

Several scientific studies have validated the neuroprotective capabilities of certain cannabinoids. First evidence of this was obtained in the 1990s, in a study involving HU-211, known as Dexanabinol. This is explained in the scientific article The biomedical challenge of neurodegenerative disorders: an opportunity for cannabinoid-based therapies to improve on the poor current therapeutic outcomes.

The research team led by Javier Fernández Ruiz has produced some of the evidence proving the influence of cannabinoids on Parkinson's disease. Mr Fernández Ruiz is Doctor of Biological Science, specialised in Biochemistry, and Professor of the Department of Biochemistry and Biology of the Faculty of Medical Studies at UCM. This research group has been investigating the properties of cannabinoids since 1987, and their neuroprotective properties since the year 2000.

"We were the first to verify the neuroprotective potential of the phytocannabinoids CBD, THC and THCV, in Parkinson's disease experimental models; and we also published the first evidence with THC, CBD, and some synthetic cannabinoids, in Huntington disease models," states Mr Fernández Ruiz. We must remember that "these studies have always been preclinical", but this team has proved that cannabinoids can help relieve the symptoms of Parkinson's disease in animal models. "We have achieved this using CB1 receptor antagonists like Rimonabant, as well as phytocannabinoids that can also block this receptor, such as THCV." In addition to animal testing, post-mortem samples of deceased Parkinson's patients have also been used on occasion to analyse some of the proteins found in the endocannabinoid system.

Neuroprotective properties of THC

In 2017 a team at the Maimonides Biomedical Research Institute of Cordoba (IMIBIC) published a scientific article on the British Journal of Pharmacology based on their work, which confirmed THC's neuroprotective properties. The study concluded that the phytocannabinoid DELTA 9-THCA can potentially protect brain cells from degenerative diseases. THCA is the naturally occurring acid form of the renowned THC, the fresh version that has not undergone decarboxylation and that we find naturally in the cannabis plant. This team of scientists discovered how it improved motor deficit and prevented neurone degeneration in mice; hence the belief that THCA could also decrease the symptoms associated to Parkinson's in humans.

Neuroprotective properties of CBD

CBD is also believed to hold neuroprotective qualities. Another clinical study involving 119 patients in São Paulo, Brazil, on the scientific basis that cannabidiol had already been proved to be neuroprotective in two previous animal trials, concluded that CBD could improve the quality of life of Parkinson's sufferers without a psychiatric history.

How to consume cannabis to alleviate the symptoms of Parkinson's disease

From the very start the aim of this post was to find out whether cannabis consumption can improve the quality of life of Parkinson's patients, and, if that is the case, what is the best way to consume it. Even though we suspected that we were not going to find a clear answer, the scientific papers contrasted for the writing of this article, and the information gathered from professionals that we have talked to, have proved that we were right. Even though the properties of some cannabinoids have already been proven to protect the nervous system or counteract muscle spasticity, this does not mean that all Parkinson's patients can benefit from cannabis consumption; and we still do not know what would be the right dosage, usage, or frequency of consumption.

The benefits that cannabis can bring to Parkinson's sufferers have been certified by the scientific research on cannabinoids, and from patients that have consumed cannabis voluntarily and have shared their experience with others. There has been an upturn of online videos by patients who claim that their quality of life has improved substantially after consuming cannabis. Some talk about their experience with CBD vaping, others ingest the oil, while others simply smoke cannabis. The most popular YouTube video is Ride with Larry, where a Parkinson's sufferer with severe spasms relaxes completely after using marijuana. But it must be remembered that these are only testimonies and not quantitative or qualitative clinical trials.

The studies carried out until now are only pre-clinical. They have studied the properties of cannabinoids but these have not been used as a treatment on Parkinson's patients. Cannabinoids have not been tested on humans to a sufficiently large extent so as to reach reliable conclusions. However, the fact that cannabinoids have improved Parkinson's symptoms in mice makes us believe that they will act on humans in the same way. CBD's muscle-relaxing properties indicate that they could be beneficial to Parkinson's patients who suffer from muscle spasticity. Nevertheless, these are only conclusions taken from the scientific studies on cannabinoids and their testing on mice, and not results from clinical trials on humans.

As a matter of fact, there are currently no cannabis-based drugs that can be prescribed to Parkinson's sufferers, although, according to Mr Fernández Ruiz, "some drugs such as Nabilone or Sativex could be used, as they are prescribed for other diseases similar to Parkinson's." Taking all this information into account, here at Dinafem we would like to advise you to talk to a qualified doctor before anything else, as cannabis could have adverse effects when combined with drugs already prescribed for the treatment of Parkinson's disease.

For the writing of this article the following studies have been researched:

Tetrahydrocannabinolic acid is a potent PPARγ agonist with neuroprotective activity, 2017, The British Pharmacological Society.

Effects of cannabidiol in the treatment of patients with Parkinson's disease: An exploratory double-blind trial, 2014, Facultad de Medicina de Ribeirão Preto, Universidad de Sao Paulo. 

The biomedical challenge of neurodegenerative disorders: an opportunity for cannabinoid-based therapies to improve on the poor current therapeutic outcomes, 2018, British Journal of Pharmacology.