Medical Cannabis as a treatment option
What is Parkinson’s Disease?
Parkinson’s disease is a nervous system condition that affects movement. Normally, the brain makes a chemical called dopamine to help control the body’s muscles. In Parkinson’s disease, the parts of the brain that make dopamine get damaged.
Parkinson’s disease worsens over time and can affect other brain functions like memory and learning.
The cause of Parkinson’s disease is not yet known. Doctors believe that genetics and environmental factors play a role.
Sometimes Parkinson’s disease is passed down from family members. People younger than 50 with the disease may have a variation in their genes. Age is also a factor - Parkinson’s is more common in people over 50.
Parkinson’s disease usually starts with mild symptoms on one side of the body. Over time, symptoms get worse and spread to the other side. In most cases, the disease progresses slowly over several years.
The most obvious signs of Parkinson’s disease are motor symptoms which affect movement, such as:
- Shaking (tremor)
- Slower movement (bradykinesia)
- Poor balance
- Problems with speech
People with Parkinson’s disease also have non-motor symptoms which are not related to movement, such as:
- Mood changes (depression, anxiety, loss of interest)
- Problems sleeping
- Loss of sense of smell
- Difficulty swallowing
- Problems with urination
- Dizziness or fainting upon standing up (postural hypotension)
Daily activities become increasingly difficult as the symptoms of Parkinson’s disease worsen. People with advanced Parkinson’s may need assistance with daily activities such as getting dressed and preparing food. They can have trouble walking and could need a wheelchair to help them get around.
Risk of falling increases because of the effect of Parkinson’s on balance and postural hypotension. Doctors recommend that people with the disease make their homes safer by adding grab bars to showers and bathtubs, removing trip hazards like loose rugs and clutter and keeping rooms well lit.
Most people with Parkinson’s can keep driving while their symptoms are mild, but as symptoms get worse they have to stop and use taxis or public transport to get around.
There is no test for Parkinson’s disease, but tests may be used to rule out other health problems. Doctors diagnose the disease by looking at a person’s symptoms and doing examinations to check reflexes, muscles and balance.
A present, no treatment can cure Parkinson’s disease or stop it getting worse. The goal of treatment is to control or improve symptoms.
Medicines for Parkinson’s
Levodopa and dopamine agonists (pramipexole, ropinirole, rotigotine) are the most commonly used medicines for Parkinson’s. They act like dopamine in the body.
Doctors may also use:
- MAO B inhibitors (selegiline, rasagiline, safinamide)
- Anticholinergics (trihexyphenidyl, benztropine, orphenadrine)
- COMT inhibitors (tolcapone, entacapone)
Medicines for Parkinson’s disease have unpleasant side effects so many people only start taking them when symptoms become severe.
Physical therapy and exercise can help to relieve pain from stiffness and posture changes caused by Parkinson’s. Some research found that exercise can improve balance, flexibility and strength, but further evidence is needed to confirm this.
A speech therapist can help people with Parkinson’s to overcome difficulty with swallowing and speech problems due to weakened muscles in the mouth.
In some cases, people with advanced Parkinson’s that doesn’t improve with other treatments have surgical procedures such as “deep brain stimulation” (DBS). Surgeons put an electronic device into the body which sends signals to the brain to reduce abnormal movement.
Your doctor can provide more information about treatment of Parkinson’s disease.
Treatment with Medicinal Cannabis
Medical Cannabis and Treatment of Parkinson’s
The cannabis plant contains many compounds which affect the human body in different ways. Cannabinoids THC (Δ9-tetrahydrocannabinol) and CBD (cannabidiol) are the most abundant active compounds. THC is responsible for the intoxicating effects of cannabis.
The effect of cannabis-based medicines on the brain in Parkinson’s disease is not well understood. Some research suggests that cannabis compounds can change dopamine signalling by interacting with the endocannabinoid system in the brain, particularly CB1 receptors. This could possibly relieve motor symptoms of the disease.
A number of preclinical trials suggest that cannabis may protect brain cells through various mechanisms, although this has not been proven in humans.
Most currently published studies on cannabis in Parkinson’s disease do not meet the clinical trial gold standard of a double-blind, placebo controlled design. Findings are limited by short duration and small sample size.
Doctors are concerned that cannabis may cause confusion or psychosis in people with Parkinson's disease. Long term effects and interactions of cannabis with other medicines are not yet fully understood. Further large scale trials of longer duration are needed before any conclusions can be drawn on the use of cannabis-based medicines in Parkinson’s disease.
- Effects of cannabidiol in the treatment of patients with Parkinson’s disease: An exploratory double-blind trial
This study compared the effect of CBD with a placebo on people with Parkinson’s disease. This trial was double-blind which means neither the patients nor the staff knew which treatment was administered.
21 patients with Parkinson’s disease were divided into three groups and given either 75 mg/day of CBD, 300 mg/day of CBD or a placebo for six weeks. Measurements of motor and general symptoms, well-being and quality of life and possible neuroprotective effects were recorded.
Results found no statistically significant difference in symptoms and neuroprotective effects, however there was an improvement in measures related to quality of life in the group receiving 300 mg/day of CBD. No significant side effects were reported in any of the groups.
- Cannabinoids reduce levodopa-induced dyskinesia in Parkinson's disease: a pilot study
This double-blind study compared the effect of nabilone - a man-made compound similar to THC - with a placebo on treatment of dyskinesia from levodopa in Parkinson’s disease. All antiparkinsonian medication was stopped for the duration of the study.
Seven patients with Parkinson’s disease and dyskinesia from levodopa were given either nabilone or a placebo in two split doses 12 hours and one hour before levodopa. Dyskinesia was measured.
Results found that nabilone significantly reduced dyskinesia in comparison to the placebo. Total dyskinesia score after nabilone was 17, compared to 22 in the placebo group.
Two patients that received nabilone withdrew from the study, one because of vertigo and the other because of postural hypotension. Other side effects of nabilone were mild sedation, “floating sensation,” dizziness, increased sensitivity to sound, disorientation, formed visual hallucinations.
- Cannabis for dyskinesia in Parkinson disease: a randomized double-blind crossover study
This double-blind study compared the effect of cannabis with a placebo for dyskinesia (abnormal movement) in Parkinson’s disease.
19 patients with Parkinson’s disease and dyskinesia from levodopa were given either a placebo or oral cannabis extract for four weeks. This was followed by a two-week washout period and then treatments were interchanged for another four weeks. Symptoms of dyskinesia were measured during this period.
Results found no improvement in symptoms from the cannabis extract.
References available at end of page.
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Cannabidiol for the treatment of psychosis in Parkinson’s disease
Journal of Psychopharmacology,
Open label case series n = 6
CBD only. Oral capsuleLink to publication
Cannabis (medical marijuana) treatment for motor and non-motor symptoms of Parkinson disease: an open-label observational study.
Uncontrolled. Open label n = 22
0.5 g cannabisLink to publication
Effects of cannabidiol in the treatment of patients with Parkinson's disease: An exploratory double-blind trial.
Journal of Psychopharmacology,
Exploratory randomized, double-blind, placebo-controlled trial n = 22.
CBD 75 or 300 mg/dayLink to publication
Survey on Cannabis Use in Parkinson’s Disease: Subjective Improvement of Motor Symptoms
VariousLink to publication
Neurokinin B, neurotensin, and cannabinoid receptor antagonists and Parkinson disease.
Randomized, double-blind, placebo-controlled trial. N = 8
Selective central (CB1) cannabinoid receptor antagonistLink to publication
Cannabis for dyskinesia in Parkinson disease: a randomized double-blind crossover study.
Randomized, double-blind, placebo-controlled crossover trial. N = 19
Whole plant extract
1.25 mg CBD and 2.5 mg THC
Cannabinoids reduce levodopa induced dyskinesia in Parkinson’s disease: a pilot study
Randomized, double-blind, placebo-controlled, crossover trial. n = 7
Not statedLink to publication
Cannabidiol can improve complex sleep-related behaviours associated with rapid eye movement sleep behaviour disorder in Parkinson's disease patients: A case series.
Journal of Clinical Pharmacy and Therapeutics,
Case series n = 4
CBD only. Oral capsuleLink to publication
Related Advocacy Groups
There are several organizations in Australia which provide information and support to people with Parkinson’s disease and their families. Below are links to their websites: