The treatment of PD may be challenging, but unlike other neurodegenerative diseases, there is effective symptomatic treatment. The treatment should be orchestrated by a neurologist with movement disorders training and tailored to the individual patient. While medical and surgical therapy can provide long-lasting benefits, the ultimate goal of therapeutics in PD is neuroprotection (the development of drugs that can halt or slow down the progression). To date, no medication has demonstrated definite neuroprotection. However, monoamino oxidase inhibitors (MAOB-I) like rasagiline (Azilect®) may have disease modifying effects. There are also several other agents that have shown sufficient promise to warrant larger trials (creatine). In addition, DaTSCAN was approved by the FDA and it can be used as a tool to monitor the dopamine system in Parkinson's disease.
There are a large number of drugs available to treat motor and non-motor aspects of PD. Symptoms can be controlled in numerous patients for many years.
Adjuvant therapy is paramount in PD. Regular daily exercise is a vital component to maintaining mobility, flexibility and balance. Research studies have shown that certain PD symptoms can be improved by aerobic exercises such as walking on a treadmill, dancing or biking, and by specific exercise modalities such as yoga, tai-chi or qi-gong. Improvement of mobility through exercise and physical therapy improves quality of life in PD. More so, studies in animal models of PD have shown that exercise may be neuroprotective, slowing the progression of disease, although more research is needed in this area.
For most people living with PD, maintaining a healthy lifestyle, proper diet and regular daily exercise are recommended for an improved quality of life. Support groups for both patients and carepartners are beneficial for psychological support, educational information and practical advice.
Drugs Used to Treat Parkinson's Disease
- Levodopa: also called L-dopa, is currently the single most effective drug for the treatment of PD. It is converted into dopamine in the brain, the neurotransmitter produced by cells in the substantia nigra. Levodopa helps control the main motor symptoms of PD. It is generally taken with another drug, carbidopa, to avoid its most common side effect, nausea. In the United States, this combination is commercialized under the name carbidopa-levodopa, Sinemet®, Sinemet® CR, or StaLevo®, a single pill containing carbidopa, levodopa and entacapone. There is controversy about how early in the disease levodopa therapy should be initiated.
- Dopamine agonists: are drugs that stimulate dopamine receptors directly in the brain, mimicking the effect of levodopa. These medications are used to treat the motor symptoms of PD, particularly early in the disease and in younger patients. They are not as potent as levodopa, but they delay the onset of motor complications associated with chronic levodopa use. Agonists currently available in the United States are pramipexole (Mirapex®), ropinirole (Requip®), and apomorphine (Apokyn®). The rotigotine patch (Neupro®) was withdrawn from the U.S. market in April 2008, but it is still available in other countries.
- COMT inhibitors: prevent the breakdown of dopamine in the brain. When taken with levodopa, the effect of a single dose is prolonged. The two COMT inhibitors available in United States are entacapone (Comtan®) and tolcapone (Tasmar®). A combination of levodopa, carbidopa and entacapone in a single tablet is available as StaLevo®.
- Monoaminooxidase inhibitors (MAOB-I): Selegiline (Eldepryl®, Zelapar®) and rasagiline (Azilect®), the two MAOB-I commercially available for the treatment of PD, also inhibit the breakdown of dopamine in the brain, prolonging its effect. Recent trials suggest that rasagiline may have disease-modifying effects (neuroprotection). An older study on selegiline indicated that the medication also slowed down the disease. The results were however inconclusive, as the benefit could have also been explained by its symptomatic effects.
- Anticholinergic medications: are drugs that block the effect of the chemical acetylcholine in the brain. Acetylcholine opposes the effect of dopamine. They are useful against tremor and stiffness. Their use is limited by their high rate of side effects. The most commonly used anticholinergic medications are trihexyphenidyl (Artane®) and benztropine (Cogentin®). Ethopropazine (Parsitan®) is available in Canada.
- Amantadine: also known as Symmetrel® can relieve the motor symptoms of PD, particularly tremor. It has a more significant effect in reducing the abnormal movements (dyskinesias) caused by chronic dopaminergic treatment.
- Other agents: medications to treat depression and anxiety, constipation, urinary and erectile dysfunction, and sleep disturbances may be necessary to optimize quality of life for people living with PD.
Complications of Drug Treatment
Most people living with PD have many years of uncomplicated treatment after the diagnosis. However, as the disease progresses over time, a significant proportion can develop treatment complications. Medication adjustments may be required to minimize them.
Motor Complications of Treatment
Motor fluctuations: refers to as “wearing-off”, “on-off” and “dose failure”. “Wearing-off” is the shortening of the benefit period of a single medication dose. An “on-off” period is a sudden and unpredictable loss of the effect of a drug and “dose failure” is the lack of any benefit from one particular medication dose.
- Dyskinesias: are uncontrollable, abnormal dance-like movements that may occur in people living with PD after years of treatment with Levodopa. These movements usually occur at the peak effect of a dose of Levodopa. Amantadine may ameliorate this complication, as well as deep brain stimulation.
- “Off” Dystonia: is manifested by abnormal twisting movements, particularly of the fingers and toes. It typically occurs in the mornings before the first dose of medication.
- Freezing: occurs when there is a sudden inability or hesitation to move (motor block). It may appear at the beginning of a movement, when going through doorways or narrow passages or when turning. It may lead to falls. Freezing does not always respond to medications.
Non-motor complications of treatment:
- Psychosis: may result from side effects of antiparkinsonian medications. It includes hallucinations, delusions and disorientation. It may also be a feature of disease progression. Reducing and eliminating some medications can be helpful. The use of atypical antipsychotic medications, such as quetiapine (Seroquel®) or clozapine (Clozaril®), may be necessary in some cases.
- Orthostatic hypotension: occurs when there is a drop in blood pressure upon standing. It may cause dizziness, lightheadedness and even fainting in some cases.
When symptoms are inadequately treated with medications, brain surgery is an option. Not every person living with PD is a good candidate for surgery. An ideal candidate is an otherwise healthy person with PD who responds well to the medication but has developed severe motor complications.
There are two surgical procedures for PD: lesioning and deep brain stimulation (DBS). Lesion procedures (also known as pallidotomy or thalamotomy) deliver energy to heat and destroy a small part of the brain. These procedures are gradually being replaced by DBS, as the latter is a reversible and programmable therapy. DBS therapy uses a medical device, similar to a pacemaker, implanted in the chest wall, and a thin, flexible wire, called a lead. The lead is located deep in the brain, in three possible areas that control movement. The device sends mild electrical signals to the lead that block some of the brain messages that cause the motor symptoms. When used in an adequate candidate, DBS can lead to improvement of all motor features of PD, and many patients are able to decrease their medications. Risks of DBS include surgical risks (hemorrhage or infection) as well as hardware complications (leads breaking, electrode malfunction or battery failure). Side effects may include language impairment and walking difficulties. Please visit our FAQs page to learn more about surgical treatments like DBS for Parkinson’s disease.