Medical Marijuana and Parkinson’s Disease

Parkinson’s Disease is a neurodegenerative disease of the brain. Because Parkinson’s is a progressive disease, Parkinson’s tends to slowly worsen over time. In a healthy brain, brain cells produce a chemical called dopamine. Dopamine is responsible for relaying messages within the brain that control movement in the human body. When these cells are damaged, the signs of Parkinson’s Disease begin to show.

Marijuana may be an excellent alternative to, or addition to, the medication regime of someone suffering from Parkinson’s Disease. Unfortunately, many of the conventional medications prescribed for a Parkinson’s patient also come with significant, negative side effects that are not present in medical marijuana. Medical marijuana offers a combination of anti-anxiety, anti-oxidant and pain relief all in one medication.Researchers issue caution for people with PD who use cannabis because of its effect on thinking.

Many people with Parkinson’s experience impairment of the executive function — the ability to make plans and limit risky behavior. People with a medical condition that impairs executive function should be cautious about using any medication that can compound this effect.

The Pharmacology of Cannabis

Marijuana contains more than 100 neuroactive chemicals that work with two types of cannabinoid receptors, type 1 (CB1) located in the brain and type 2 (CB2) located in the peripheral immune system. Cannaboids have powerful, indirect effects on these receptors, but researchers are unsure how. People with PD have less CB1 receptors than people who do not have PD. A boost to the CB1 receptor through an agonist, like marijuana, can improve tremors and may alleviate dyskinesia. Similarly, the other receptor, CB2, is also being studied to determine if it can modify the disease or provide neuroprotective benefits. However, a unified hypothesis does not currently exist for either receptor because there is too much conflicting data on the effectiveness of cannaboids and these receptors.

Cannabis can contain two different types of molecules that interact with cannabinoid receptors: agonists and antagonists. An agonist is a drug that attaches to the same receptor as a natural chemical and causes the same effect. A dopamine agonist is a drug that is not dopamine, but attaches to the dopamine receptor. An antagonist is different as it attaches to the receptor, but blocks the action of the natural chemical. Some drugs are dopamine antagonists, which block dopamine and are dangerous for people with PD. Medical marijuana can contain both cannabinoid agonists and antagonists. Recreational marijuana use is derived from its effects on agonists.

The varying amounts of cannabinoid agonists and antagonists in different marijuana plants makes cannabis studies difficult to conduct. When researchers study the effects of a drug, dosages are controlled and often set to a specific number of milligrams. When testing medical marijuana, the dosage administered can vary dramatically depending on the plant and method of administration.

Delta-9-tetrahydrocannibinol (THC)

THC is a type of cannabinoid and the primary component of marijuana. It has a long latency of onset and cannot be easily measured for a therapeutic or medicinal dose. Medical marijuana studies primarily provide participants with THC in the form of a capsule, nasal spray or liquid.