Parkinson’s disease is the second most common neurodegenerative disorder that affects the body’s motor function. The disorder causes the neurons in the brain to gradually break down or die off. This loss of neurons causes dopamine levels to also decrease, which causes abnormal brain activity. This then leads to the manifestation of the signs and symptoms of the disease.
The progression of the symptoms of the disease might vary from person to person. The signs and symptoms of Parkinson’s disease include tremors, slowed movement, rigid muscles, impaired posture and balance, loss of automatic movements, speech changes, and writing changes. Other patients may also experience anxiety, depression, and dementia.
Depending on the organization that treats and researches the neurodegenerative disease, it is said that patients go through several stages of disease progression. According to the Parkinson’s Foundations, there are five stages of the disease:
Stage 1 – The symptoms are mild and don’t interfere with the person’s quality of life
Stage 2 – The symptoms worsen and daily activities become more difficult, taking more time to complete.
Stage 3 – This stage is considered as the mid stage of the disease. The patient loses balance, moves more slowly, and falls are common. The symptoms impair daily activities such as dressing, eating, and brushing of teeth.
Stage 4 – The symptoms become severe and the patient often needs assistance in walking and performing daily activities.
Stage 5 – The most advanced stage of the disease. In this stage, the patient is unable to walk and will require full time assistance with living.
The cause of Parkinson’s disease is still unknown, but it is believed that factors such as genetics and environmental factors may play a role in increasing the risk of developing the disorder. According to statistics, about 1 million Americans are living with Parkinson’s disease and there are about 600,000 new cases are diagnosed annually.
There is currently no cure for Parkinson’s disease. However, treatment options are available to help minimize and manage the symptoms. To help with the symptoms, doctors will often prescribe pharmaceutical drugs and for later cases, surgery might be advised. Aside from these, doctors might also recommend lifestyle changes such as exercise, physical therapy, and speech therapy.
Medications for Parkinson’s disease work by either increasing dopamine or serve as substitutes for the neurotransmitter. Below are the various medications usually prescribed for the management of the disease’s symptoms:
Carbidopa-levodopa is a drug used to increase brain dopamine concentrations, believed to improve nerve conduction and assist the movement disorders associated with Parkinson’s disease. Carbidopa is combined with levodopa to protect the latter from premature conversion to dopamine. However, patients might experience side effects such as nausea, dry mouth, loss of appetite, heartburn, diarrhea, constipation, headache, dizziness, drowsiness, blurred vision, sneezing, stuffy nose, cough, other cold symptoms, muscle pain, numbness, trouble sleeping, and itching.
Unlike levodopa, the need for metabolic conversion into dopamine is obviated. Instead, the dopamine agonists mimic the dopamine effects in the brain. While these drugs do not work as well as levodopa in managing the symptoms of Parkinson’s, they do last longer. Usage of these drugs might cause similar side effects of using carbidopa-levodopa. Aside from that, it might also include hallucinations, sleepiness, and compulsive behaviors (eg. hypersexuality, gambling, eating).
Monoamine oxidase B (MAO-B) inhibitors
MAO-B inhibitors work by helping prevent the breakdown of dopamine by inhibiting the MAO-B enzyme, which is responsible for metabolizing dopamine. Usage might cause side effects such as heartburn, nausea, dry mouth, insomnia, and dizziness. In some cases, it might also cause confusion, nightmares, hallucinations, and headaches.
Catechol-O-methyltransferase (COMT) inhibitors
Similar to carbidopa, COMT inhibitors also prolongs the effect of levodopa therapy by blocking the enzyme responsible for the metabolism of dopamine. However, patients might experience side effects such as urine discoloration, diarrhea, vivid dreams, visual hallucinations, drowsiness, and impairment of voluntary movement (dyskinesias).
Anticholinergics are still used to help control the tremors associated with Parkinson’s disease. However, they cannot help with other symptoms such as slowness of movement (bradykinesia), rigidity, gait disturbance, and other features of advanced Parkinson’s disease. This is why anticholinergics are often used to treat tremors that are not adequately controlled by dopaminergic medications. Usage of the drug might cause side effects such as impaired memory, confusion, hallucinations, constipation, dry mouth, and impaired urination.
The exact mechanism of amantadine is not yet fully understood. However, usage of the drug is known to cause an indirect increase in dopamine release and the direct stimulation of dopamine receptors. Patients might experience side effects such as purple mottling of the skin, ankle swelling, hallucinations, gastrointestinal discomfort, nausea, sleep disturbance, and nervousness.
Parkinson’s Disease and Medical Marijuana
Because of the cannabinoids naturally found in medical marijuana, it provides benefits for various diseases and disorders by stimulating the cannabinoid receptors found in the body. Some doctors and researchers have started looking at medical marijuana as an alternative to managing the symptoms of Parkinson’s disease and to help with the side effects caused by medications.
According to several studies and anecdotes, usage of medical marijuana improved the symptoms of patients such as bradykinesia, tremors and rigidity. Other studies have also looked into the ability of medical marijuana to reduce anxiety and stress levels of Parkinson’s patients. Meanwhile, another study found that medical marijuana might help in minimizing the dyskinesia caused by levodopa usage.