Parkinson’s disease (PD) is a chronic, progressive disease that affects the nerve cells in the brain and the body. It is not known exactly what causes the disease, although it is believed to be a combination of genetic and external factors. Current treatments alleviate the motor symptoms of PD. However, there is no known cure for PD, and currently, there are no treatments that can slow the progression of the disease.
Treatment for PD is focused on managing the symptoms to improve the individual’s quality of life. Although PD has some common features and symptoms, the disease can show up differently across different patients. Treatment is highly individualized to meet the needs of the unique patient and may include medications, surgery (deep brain stimulation), physical rehabilitation, exercise, and complementary and alternative medicines.
Treating the motor symptoms of Parkinson’s disease
Motor symptoms are those that affect a person’s ability to move. PD is characterized by four primary motor symptoms:
- Tremor – a shaking of the hands, arms, foot or legs, when the limb is at rest
- Rigidity – an abnormal stiffness in a limb or part of the body
- Postural instability – impaired balance or difficulty standing or walking
- Bradykinesia – gradual loss and slowing down of spontaneous movement1,2
In addition to the primary motor symptoms, PD may cause a number of secondary motor symptoms, including:
- Freezing of gait or shuffling gait
- Micrographia (abnormally small or cramped handwriting)
- Unwanted accelerations in movement or in speech
- Speech difficulty or changes in speech
- Stooped posture
- Dystonia (prolonged muscle contractions that can cause twisting of body parts or repetitive movements)
- Impaired fine motor dexterity
- Poverty of movement
- Akathisia (restless movement)
- Difficulty swallowing
Initial therapy for motor symptoms of PD is usually levodopa (administered in combination with carbidopa), dopamine agonists, and/or monoamine oxidase-B (MAO-B) inhibitors. The combination of levodopa and carbidopa is the most effective treatment available for the management of motor symptoms of PD. However, it can cause a side effect known as dyskinesia, which is abnormal involuntary movements. In addition, there are motor fluctuations with “on” periods when the patient receives positive effects of the drug and “off” periods when the motor symptoms return. Some of these symptoms are caused by the levodopa wearing off during the day.
Dopamine agonists are less effective on the motor symptoms of PD but have a lower rate of causing dyskinesia, although they have other side effects. MAO-B inhibitors are less effective than levodopa or dopamine agonists, however they have fewer side effects. Choice of therapy should be customized to the individual patient with an understanding of the risks and benefits of each class of medication and stage of disease progression.4
In addition to medication, physical therapy can help with muscle cramps, and regular exercise and stretching are beneficial to strengthen muscles and maintain flexibility. Assistive devices such as walkers or canes may be helpful.
For some patients whose symptoms are not adequately controlled with medication, surgery to implant a device that provides deep brain stimulation (through electrical impulses) may be an option. As with medication, this surgery does not cure or change the course of the disease progression, but it may help with the symptoms of PD.2
Treating the non-motor symptoms of Parkinson’s disease
Besides the motor symptoms, PD can cause a number of non-motor symptoms that affect other brain and body functions, such as:
- Gastrointestinal issues, such as constipation
- Urinary issues
- Sleep problems
- Orthostatic hypotension (a drop in blood pressure that occurs upon standing)
- Reduced sense of smell
- Mood changes, like depression or anxiety
- Cognitive changes, like, slowed thinking, confusion, or difficulty orienting oneself in familiar locations, or dementia
- Hallucinations, delusions, or paranoia
- Sexual dysfunction
- Weight loss or weight gain
- Vision problems
- Dental problems
- Skin problems
- Impulsive behaviors1,3
Treatments of the non-motor symptoms are specific to the symptoms experienced. Some of the non-motor symptoms, such as constipation, some sleep problems, psychotic symptoms, or impulsive behaviors, may be caused as a side effect of medications used to treat the motor symptoms of PD.
Other non-motor symptoms have both pharmacological and other therapy strategies that can help. For example, among the non-motor symptoms, there are medications that can work to reduce over-activity of the bladder in people who experience urinary problems, and pain may be relieved through a combination of medication, physical therapy, and exercise. Complementary therapies, such as acupuncture or massage, may also help relieve non-motor symptoms of PD.3
Because treatments for some of the non-motor functions can interact with PD treatments and cause unwanted or dangerous side effects, it is critical that the patient see a neurologist, particularly a movement disorders specialist who is specially trained in understanding how these drugs can affect a PD patient.