INTRODUCTION TO PARKINSON'S DISEASE
Often times, the diagnosis of Parkinson's disease is accompanied with little or no information about its cause, prognosis or management. Here you will find some helpful information that will help you better understand PD. For additional information on the disease, health care referrals and community resources contact the Parkinson Foundation Western Pennsylvania at 412-837-2542.
Parkinson's disease (PD) is a progressive neurodegenerative disorder first described by Dr. James Parkinson in "An Essay on the Shaking Palsy" in 1817.
Some physicians use the term "parkinsonism" in the initial evaluation and diagnosis. Parkinsonism is an umbrella term applied to the clinical syndromes that share the cardinal movement disorders of resting tremor, bradykinesia, rigidity and postural instability.
Idiopathic Parkinson's disease or what is commonly referred to as Parkinson's disease (PD) makes up about 85% of all the parkinsonism syndromes. Idiopathic means unknown cause or origin.
Young Onset Parkinson's disease (YOPD) is a subgroup of idiopathic PD made up of those diagnosed before the age of 50. Although the disease is essentially the same as it is when diagnosed later in life, the issues surrounding the disease are different.
A clinical diagnosis of PD is made by assessing motor function or movement.
The diagnosis is made by the presence of at least two of the four cardinal motor or movement symptoms associated with PD. When the symptoms are present, medications which are known to reduce the symptoms are then often used to increase the likelihood of making a correct clinical diagnosis.
No one is sure, but many risk factors have been discovered which likely contribute to developing Parkinson's disease. The extent to which each risk factor is involved though is still not understood from person to person.
Aging is considered one of the primary risk factors because it is very uncommon before the age of 30, and incidence rates increases with age. It has been established that there is a decline in dopamine concentrations of 5-8% per decade after the age of 30.
Family link or genetic predisposition
Research studies show a genetic link or predisposition associated with developing Parkinson's disease. White males are more likely to be diagnosed with Parkinson's disease than African American males and Asian males are at lower risk than both white and African American males. There are currently as many as 20 genetic mutations being investigated in association with PD.
In discussing the possible causes of PD, there is a saying that if age and genetics load the gun, the environmental factors pull the trigger”. In most cases of Parkinson’s, the environmental factors alone are not sufficient enough to cause the disease but likewise in most cases they do play a role. Environmental triggers identified so far include:
- Traumatic head injuries
- Heavy metals
- Welding exhaust
- Viral infections
- Increased oxidative stress
- Mitochondrial dysfunction
Parkinson's disease affects about 1 in 300 people in the general population. The prevalence increases with age to about 1.6% (1,560 per 100,000) in people over the age of 65. There are currently between one million and 1.5 million in the United States with Parkinson's disease. Most people are diagnosed with the disease between the ages of 55 and 65 and about 85 percent of people with Parkinson's are over the age of 65. There are an estimated 60,000 - 70,000 new cases of PD diagnosed each year and this number is increasing yearly as the population of the United States shifts. Men are almost 1.55 times more likely to be diagnosed than women.
There are four cardinal symptoms. At least two of these symptoms must be present in order for a physician to suspect a diagnosis of Parkinson's disease.
- Most recognized symptom
- Seen initially in about 75% of persons with PD
- Typically begins on one side
- More noticeable at rest
- Often presents as "pill rolling"
- Increases with stress
- Tremor can involve hands, arms, foot, leg, chin, jaw, or tongue
- Involuntary increase in muscle tone resulting in continuous resistance
- Tremor superimposed on the rigidity presents as a ratchet-like sensation known as "cog wheeling"
- Rigidity underlies the stooped posture, forward flexed head, flexed knees and elbows
- (Slowness of movement ) is the central, most significant movement disorder in PD
- Inhibits all aspects of activities of daily living (ADL)
- Secondary effects include decreased arm swing while walking & eye blink, facial masking, slowed chewing & swallowing
- Typically the last of the "cardinal" symptoms to appear
- Not usually responsive to dopaminergic treatment
- Appears to be a problem with the "righting reflex"
There are a number of secondary motor symptoms and non-motor features that are associated with Parkinson's disease also.
Some of the secondary motor symptoms include:
- Small, cramped handwriting (micrographia)
- Stiff facial expression
- Shuffling walk
- Stooped posture
- Muffled speech
- Decreased eye blinking and arm swinging while walking.
Some of the non-motor features include
- Olfactory Dysfunction
- Visual Dysfunction
- Behavioral Dysfunction
- Sleep Disturbances
- Respiratory Dysfunction
- Autonomic Dysfunction
Parkinson’s is a chronic progressive disease. Over time, symptoms will get worse. Although it typically progresses slowly, the rate or speed of progression varies considerably from person to person. There are several different rating scales that doctors and other professionals can use to measure the progression of the disease in an individual. Very simply, progression of the disease can be broken down into five stages. Remember that these stages are somewhat subjective as is the perceived rate of progression.
During this initial stage, the person has mild symptoms that generally do not interfere with daily activities. Tremor and other movement symptoms occur on one side of the body only. Friends and family may notice changes in posture, walking and facial expressions.
In stage two of Parkinson’s, the symptoms start getting worse. Tremor, rigidity and other movement symptoms affect both sides of the body. Walking problems and poor posture may become apparent. In this stage, the person is still able to live alone, but completing day-to-day tasks becomes more difficult and may take longer.
Stage three is considered mid-stage in the progression of the disease. Loss of balance and slowness of movements are hallmarks of this phase. Falls are more common. Though the person is still fully independent, symptoms significantly impair activities of daily living such as dressing and eating.
During this stage of Parkinson’s, symptoms are severe and very limiting. It’s possible to stand without assistance, but movement may require a walker. The person needs help with activities of daily living and is unable to live alone.
This is the most advanced and debilitating stage of Parkinson’s disease. Stiffness in the legs may make it impossible to stand or walk. The person requires a wheelchair or is bedridden. Around-the-clock nursing care is required for all activities. The person may experience hallucinations and delusions. While stage five focuses on motor symptoms, the Parkinson’s community acknowledges that there are many important non-motor symptoms as well.
Physicians can use different combinations of management strategies based on the needs of each patient and treatment philosophy.
Common treatments for PD include:
- Dopamine Replacement Therapy Carbidopa/Levodopa products increase the amount of dopamine in the affect area of the brain
- Dopamine Supplementation Therapy Dopamine agonists make the existing dopamine more effective by binding to receptor sites on the neurons
- Inhibition Therapy
Inhibitors that block the breakdown of levodopa and/or dopamine include:
- MAO-B inhibitors
- COMT Inhibitors
Deep Brain Stimulation (DBS)
In certain patients, DBS can treat the same symptoms as levodopa, but can minimize dyskinesia, wearing off and tremor. This procedure makes use of electrodes placed in the midbrain and hooked up to pacemaker type devices to improve or manage symptoms. DBS may also decrease the need for medication.
Although appropriate medical management lays the foundation for controlling the motor symptoms self-care or self-management practices are essential for optimal disease management and should include:
- Sound nutrition and dietary considerations
- Stress management
- Social Engagement
There is much research being done that scientists hope will lead to identifying the cause and, eventually, discovering a cure. Cell transplantation, gene therapy and the injection or stimulation of nerve growth factors may offer a potential cure in the future.
To date there is no cure for Parkinson's disease. In addition, because there is no definitive cause for the disease, it is not preventable. The management of Parkinson's disease is based on relieving the symptoms as much as possible.