Medical marijuana and Parkinson's disease
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Parkinson’s disease is a complex brain disorder that affects over 10 million people across the globe. While treatment has come a long way over the years, the drugs used to manage the symptoms of this disease often cause severe adverse effects.
Today, as medical marijuana attracts the attention of more and more medical professionals and researchers, some patients are tempted to turn to cannabis for relief from some of these symptoms.
Parkinson’s is a neurodegenerative brain disorder. It affects both the central nervous and motor systems. The disease progresses slowly, generally creating a variety of physical and behavioural symptoms over time.
Parkinson’s disease causes a death of brain cells in the substantia nigra, a region of the midbrain, which essentially stops dopamine production. Dopamine is a neurotransmitter that plays a vital role in managing movement and emotional responses, as well as regulating the brain's reward and pleasure centers. It can help us see rewards as well as take action to ultimately get them.
As dopamine levels drop in the brain, Parkinson’s patients slowly lose the ability to control their body, movements, and emotions. This eventually leads to obvious physical symptoms like tremors, rigidity, difficulty walking, and more, as well as behavioural symptoms such as dementia and depression.
Parkinson’s disease is a long-term condition that generally progresses slowly. Most patients take years to develop symptoms and live with the disease for years to come. Parkinson’s itself isn’t actually a fatal disease; instead, it can lead to a series of other health complications.
SYMPTOMS OF PARKINSON’S
Parkinson’s essentially stops dopamine production in the brain. This affects a person’s ability to complete smooth, coordinated muscle movements, and goes on to produce 4 main types of motor symptoms. These are:
- Slow movement (also known as bradykinesia): This symptom makes it harder for patients to initiate and perform physical movements. This can affect a person’s ability to get out of bed, button a shirt, or even speak.
- Tremors: The tremors caused by Parkinson’s usually take place in the hands but can also affect other parts of the body, including the lower lip, jaw, or legs. Tremors generally are at their worst at rest and tend to improve once a patient begins using the affected limb or body part in some way.
- Stiffness: Parkinson’s patients may find that certain parts of their body (especially the arms, legs or trunk) are particularly stiff, tight, or achy.
- Postural instability: Many Parkinson’s patients may develop problems balancing and are therefore at an increased risk of falls. Tasks such as walking, balancing, or turning around may become increasingly difficult. This symptom usually develops in the later stages of the disease and isn’t generally present during diagnosis.
These symptoms start to take place when roughly 60-80% of the brain’s dopamine-producing cells are damaged. Other secondary motor symptoms of Parkinson’s include:
- Micrographia (small, cramped handwriting).
- Foot dragging, usually on one side of the body, resulting in a shuffled walk.
- Freezing, or seeming physically stuck in place while walking.
- Rigid facial muscles and a consequential loss of facial expression.
- Speaking in a low, muffled voice, also known as hypophonia.
- A tendency to fall backwards.
- A decreased ability to perform automatic reflexes such as blinking and swallowing.
Parkinson’s disease also produces a variety of non-motor symptoms. These symptoms, while less obvious, can actually be more troublesome than traditional motor symptoms, having a large impact on a patient’s quality of life.
Non-motor symptoms caused by Parkinson’s disease include:
- Mood disorders such as anxiety, depression, or irritability.
- Cognitive problems, such as difficulties concentrating, slow thoughts, difficulties with memory and language, dementia, and personality changes.
- Hallucinations and delusions.
- A drop in blood pressure when standing, causing light-headedness.
- Sleep disorders including insomnia, excessive daytime sleepiness, vivid dreams, restless leg syndrome, and more.
- Eating disorders, such as early satiety (feeling full after small amounts of food).
- Pain and fatigue.
- Excessive sweating.
- Vision problems.
- Decreased sense of smell.
- Weight loss or gain.
- Impulsive control disorders such as binge eating, excessive shopping or gambling. This is usually a side effect of medications.
There is no cure for Parkinson’s. Instead, the focus of treating the disease is placed on minimizing the effect and severity of symptoms and increasing a patient’s overall quality of life as much as possible.
Treatment usually involves medications that aim to either replenish dopamine levels temporarily or mimic the function of dopamine. These types of drugs are called dopaminergic medications and help reduce muscle rigidity, improve speed and coordination of movement and lessen tremors.
The most common used drugs in Parkinson’s treatment are levodopa (used to temporarily boost dopamine levels in the brain), several dopamine agonists (used generally to offset motor symptoms in their early stages), and MAO-B inhibitors (used to increase dopamine levels by temporarily stopping its metabolism).
These medications can produce a wide variety of side effects. Only about 5-10% of levodopa passes through the blood-brain barrier, for example. The rest is often absorbed elsewhere, which creates a wide variety of adverse effects such as nausea, joint stiffness, and dyskinesia (involuntary, erratic writhing movements of the face, arms, legs, and trunk). Apomorphine is sometimes used to minimize dyskinesias, but produces other side effects such as hallucinations and confusion.
Dopamine agonists also produce a variety of mild, yet significant adverse effects, including drowsiness, hallucinations, insomnia, nausea, and constipation. Some of these side-effects can be caused even in minimum doses, forcing doctors to look for other alternatives.
Parkinson’s medications may have interactions with certain foods, other medications, vitamins, herbal supplements, over-the-counter cold pills and other remedies.
Prior to the discovery of levodopa, surgery was also a common practice for dealing with motor symptoms. However, it is still being used for patients with very advanced Parkinson’s whom no longer benefit from drug treatment. Surgery usually involves deep brain stimulation of areas such as the thalamus, the globus pallidus or the subthalamic nucleus. Other, less common, surgical therapies involve intentional formation of lesions to suppress overactivity of specific brain areas.
Rehabilitation is also a common practice in Parkinson’s treatment, as evidence suggests that physical activity may help speech and mobility problems. Rehabilitation programs usually involve a physiotherapist or other professionals who specialize in working with patients with Parkinson’s.
CANNABIS AND PARKINSON’S: THE TREATMENT OF THE FUTURE?
Cannabis is beginning to play an important role in treating both physical conditions as well as complex neurological conditions like Parkinson’s. Since the discovery of cannabis’ unique medical potential and the legalization of the drug across many parts of the world, research is beginning to focus on how this age-old medicine may help manage Parkinson’s symptoms and provide patients with an improved quality of life.
The cannabinoids in cannabis interact with our body’s endocannabinoid system, which is made up of a variety of receptors (mainly CB1 and CB2, although there are others). Parkinson’s patients are known to have less CB1 receptors, and research suggests that CB1 agonists can improve tremors and may alleviate dyskinesia.
In 2001, researchers from the Department of Neurology at the Manchester Royal Infirmary conducted a randomized, double-blind, placebo-controlled, crossover trial that examined how cannabinoid receptor agonists may help alleviate dyskinesias caused by levodopa.
In 2014, researchers from the Department of Neurology at the Rabin Medical Center in Israel performed a small scale, open-label observational study on 22 patients suffering from Parkinson’s.
The patients smoked cannabis and were evaluated at baseline and 30 minutes after consuming marijuana using a variety of scales, such as the Unified Parkinson Disease Rating Scale, visual analog scale, present pain intensity scale, Short-Form McGill Pain Questionnaire, and more.
The researchers observed an overall improvement in motor symptoms within 30 minutes of consuming cannabis. The researchers cited especially noticeable improvements in tremor, rigidity, and bradykinesia. Patients also experienced a reduction in pain severity and improved sleep.
However, not all the research into cannabis is positive. For example, an evaluation of the effects of cannabinoid receptor agonists on the severity of motor symptoms and levodopa-induced dyskinesias showed that, while the tested drugs were safe, they did not improve Parkinsonian motor disability.
Other research is also looking at the unique neuroprotective properties of cannabis, which may help slow the effect of Parkinson’s on dopamine producing cells in the brain. Furthermore, research into cannabis suggests the drug is effective in treating nausea and vomiting, a wide variety of pain, and insomnia which, while not directly treating Parkinson’s, may help alleviate its symptoms or adverse effects of treatment.
As is often the case with cannabis research, more insight into the relationship between cannabinoids, the endocannabinoid system, and Parkinson’s disease is needed in order to fully understand whether cannabis can provide any benefits to patients.
Despite some promising results, the existing studies on cannabis are limited. They either focus on small samples of patients, or simply don't meet the “gold standard” for medical trials, which should be random, double blind, placebo controlled, and multidirectional.
A lot of evidence for cannabis’ medicinal properties relies on anecdotal reports from patients or observational studies which may be awe-inspiring but are not enough to warrant a conclusive statement about whether cannabis is beneficial for treating this disease.
However, legalization is already helping to change opinions about cannabis and its use (both medicinally and recreationally). Hopefully this will lead to further research into the drug so patients suffering from complex conditions like Parkinson’s may soon find a new, effective, reliable, and safe way to manage their conditions or symptoms.
Note: We have taken the utmost care and precaution whilst writing this article. That being said, please take note of the fact that we are not medical professionals of any kind. Cannabis.info is strictly a news and information website. This content is not intended to be a substitute for professional medical advice, diagnosis, or treatment.