Understanding CBD

People with PD are eager to find alternative methods to help their symptoms, leading many of these patients to look into whether other therapies, such as medical marijuana, also known as medical cannabis, can be useful. Previously, I wrote a blog on medical marijuana and PD which you may find interesting.

More recently, I have received many inquiries specifically about the use of cannabidiol or CBD, for symptoms of PD.  So today I’ll take a more in-depth look at CBD to help you better understand what it is and its possible use for symptoms of PD.

(Of note, the acronym for CBD is confusing in the context of PD, since the acronym is also used to refer to cortico-basal degeneration, a neurodegenerative disease that shares some clinical properties with PD. In this article, CBD refers to cannabidiol).

What is CBD?

Cannabidiol, or CBD, is one of the two main components of medical marijuana. (The other one is tetrahydrocannabinol or THC.) Pure CBD does not cause a “high” and does not pose a risk of abuse or dependence. THC on the other hand, can cause these effects.

Pre-clinical evidence that CBD has anti-inflammatory and antioxidant properties

CBD has been studied extensively in the laboratory and has been shown to have anti-inflammatory and antioxidant properties. Inflammation in the nervous system has been linked to neurodegeneration and therefore it has been hypothesized that CBD might even be beneficial as a neuroprotective agent. Although this is interesting and potentially exciting information, there are numerous other chemicals that have been studied in the laboratory with these properties that did not result in clinical benefit when tried in humans. Therefore, clinical trials become essential to support any claims that CBD should be used for medical purposes. Bottom line, don’t get too excited until there is scientific data to back it up.

Is CBD legal?

There is a lot of confusion around this question, related to the fact that the law distinguishes between CBD extracted from hemp and CBD extracted from marijuana. In reality, hemp and marijuana are two different names for the cannabis plant, with hemp defined as cannabis containing less than 0.3% THC.  CBD products derived from hemp are federally legal. On the other hand, CBD derived from a cannabis plant containing more than 0.3% THC is federally illegal – even if the CBD is purified and the product itself contains less than 0.3% THC.  To add to the confusion, is the fact that each state has its own laws that govern the use of CBD products which often contradict federal law.

The increased interest in CBD products as supplemental treatment

There is also a very confusing array of CBD products that are available for purchase. These vary in:

• What the manufacturers state is in the product. That is, some formulations of CBD will state on their label that they also contain a small amount of THC or that they contain other cannabis-derived compounds, but not THC. Others state that they are pure CBD.
• The formulation. CBD is available in oils, creams, pills, inhalants and more.

It is not just the Parkinson’s disease community that has taken an interest in CBD.  There are countless health claims that CBD is helpful for a whole host of conditions. Clinical trial evidence to support the use of CBD however, is minimal. The only FDA-approved indication for CBD is to reduce seizure frequency in certain rare and severe forms of childhood epilepsy. A purified form of CBD, sold under the brand name Epidiolex® was tested in a well-designed clinical trial in order to gain this approval. (Three other cannabis related drug products that are not CBD, but rather synthetic THC, also have FDA approval and are used to treat loss of appetite and weight loss in patients with HIV, and severe nausea and vomiting due to chemotherapy).

For all the other health claims, there is not enough clinical trial data to allow the FDA to state whether or not CBD is effective. And there definitely is not enough data to support the use of one type or formulation of CBD over another.

This has not dimmed the enthusiasm of millions of CBD users for a wide range of medical conditions.

The challenge of regulating CBD products

Practically, CBD products can be obtained relatively easily at health food stores and online. They are not considered drugs (except for Epidiolex®), and therefore are not regulated by the Food and Drug Administration (FDA). This can be very problematic because without FDA oversight:

• There is no assurance that what is stated on the package is what is being sold. For example, even if the bottle says it is pure CBD, the product may contain other chemicals from the cannabis plant, or a higher amount of THC than advertised
• The manufacturing process, which is also not regulated, may introduce contaminants
• There is no assurance that the dosage written on the bottle is correct
• Medication interactions between CBD products and other drugs are not clear to consumers

The FDA is aware of the health claims that are made by manufacturers about various products and issues warnings to companies who market CBD products with unsubstantiated health claims.

CBD and Parkinson’s Disease

What evidence is available for the use of CBD for PD?

The FDA is aware that patients are frustrated that our understanding of how best to use CBD remains minimal because of the lack of clinical trials. In 2015, the FDA changed some of their regulations to make it easier to study CBD in clinical trials.

There have been a few studies of CBD for various symptoms of PD which have generally involved a small number of patients.  Many have been open-label trials, in which the doctor and patient are both aware that the patient is receiving treatment and there is no control group that received a placebo.

• In one, an open label study of CBD was conducted on six patients with psychosis. Psychotic symptoms decreased.
• In a second trial, an open-label study of CBD was conducted on four patients with REM behavior sleep disorder. Symptoms decreased.
• A third trial was conducted on 21 patients with PD and was double blinded, meaning neither patient nor doctor knew who received treatment and who received a placebo. Motor scores did not improve, but quality of life scores did.

Additionally, three more recent trials of CBD for PD were conducted.

• One open-label trial of 13 patients studied the tolerability and efficacy of CBD on tremor in PD. The trial is completed but results have not yet been published.
• Epidiolex®, the CBD formulation approved by the FDA for certain intractable childhood epilepsies, was trialed in 10 people with PD in an open-label study. Results were published and showed improvements in motor scores, nighttime sleep and emotional dysregulation scores.
• Finally, a double blinded study for motor symptoms of PD is currently underway. This trial aims to enroll 60 people with 30 patients receiving CBD and 30 receiving placebo.

Using CBD for treating Parkinson’s disease symptoms

People with PD are already using CBD in various forms for all sorts of symptoms of PD including insomnia, anxiety, tremor, dystonia and pain.

Without clinical trial data however, we do not know whether CBD is safe and effective for a particular symptom, and if it is, what CBD formulation and dosage is best to be used for a particular symptom.

We also don’t know the side effect profile of CBD in people with PD.  At baseline, people with PD may have various non-motor symptoms that may make them more prone to side effects from CBD, including fatigue and nausea.

If you would like to try CBD for one of your PD symptoms, have a conversation with your movement disorders specialist about it. Your doctor may be willing to oversee your trying it, or may feel that it is too risky for you without evidence that it will help. At the very least, he/she can make sure that there are no drug interactions between CBD and anything else that you take and discuss with you any potential side effects that you need to be aware of.

Tips and takeaways

• CBD is a component of medical marijuana that does not have abuse or addiction potential
• CBD products can be easily obtained in health food stores and online, but they are not regulated by the FDA
• There is minimal clinical trial data that support CBD-related health claims
• Despite this, various CBD products are used by people with PD (and by people with a multitude of other conditions) for symptoms such as pain, insomnia, and anxiety
• More clinical trials are necessary to understand whether and how to safely and effectively use CBD for the treatment of PD symptoms
• As with all medical decisions, if you would like to use a CBD product, first talk with your neurologist and other members of your health care team