The Progression of Parkinson`s Disease

In 1817, British surgeon-apothecary, James Parkinson, wrote a treatise on a condition he had observed in several patients and neighbors which he termed paralysis agitans, or shaking palsy. Now known as Parkinson’s disease, this complex neurological disorder is estimated to affect at least 1 million Americans. This chronic and progressive disorder, marked by increasing worsening of symptoms, is second only to Alzheimer’s as the most prevalent neurodegenerative disease Parkinson’s disease occurs when neurons in the brain die or become impaired, commonly from an area near the base of the brain, the substantia nigra. The death of the neurons result in abnormal nerve firing patterns in the brain, which cause impaired movement. 

The disease causes both motor and non-motor symptoms. The four primary symptoms of Parkinson’s are tremor, rigidity, bradykinesia, and postural instability. However, the disease affects everyone differently, and the particular symptoms and rate of progression differs among patients. Typically, symptoms begin on one side of the body but will eventually affect both sides. Common symptoms that may accompany the disease include: depression and emotional changes, difficulty chewing and swallowing, speech changes, bladder or bowel problems, sexual dysfunction, sleep problems, orthostatic hypotension, muscle cramps and dystonia, pain, fatigue, and dementia or cognitive problems (more severe in late-stage Parkinson’s).

The cause of Parkinson’s disease is unknown, although genetic mutations, environmental factors, and mitochondrial dysfunction may play a role. The disease affects about 50% more men than women, although the reasons for this are unclear. The average age of onset of Parkinson’s disease is 60, but about 5%-10% of people with the disease have early-onset, beginning before age 50. The incidence of the disease rises significantly with advancing age. 

Diagnosis and Treatment

Parkinson’s disease can be challenging to diagnose as there are currently no blood or laboratory tests to aid in identification of the disease. Thus, diagnosis must be based on medical history and neurological examination. To further complicate diagnosis, early signs of the disease are sometimes dismissed as symptoms of normal aging. Brain scans, such as magnetic resonance imaging (MRI) or computed tomography (CT) are sometimes used to rule out other diseases. 

Neurologists commonly use rating scales, such as the Hoehn and Yahn Staging of Parkinson’s Disease or the Unified Parkinson’s Disease Rating Scale, to stage progression of the disease. While there is currently no cure for Parkinson’s, medications, and sometimes surgery, may improve motor and other symptoms. 

In general, there are three categories of medications used to treat Parkinson’s: those which increase dopamine levels in the brain, such as dopamine precursors; those which affect other neurotransmitters in the body in order to lessen symptoms, such as anticholinergic medications; and, medications to help with non-motor symptoms, such as antidepressants.

In more severe cases, deep brain stimulation using a surgically implanted electrode in the brain can help block signals that cause many of the motor symptoms of Parkinson’s disease.  

Challenges in Managed Care

It is estimated that approximately 60,000 Americans are diagnosed with Parkinson’s disease each year. Because age is the greatest risk factor for Parkinson’s, it is likely that the disease will increase in prevalence as the population ages.

The economic burden of Parkinson’s disease is substantial. In 2013, researchers combined information from national surveys to create a burden of Parkinson’s disease model. The study, published in the journal Movement Disorders, revealed that the economic burden of the disease is at least $14.4 billion a year in this country, and that the prevalence of Parkinson’s is projected to double by 2040. Patients with Parkinson’s disease incurred disease-related medical expenses of $22,800 per patient—$12,800 higher than someone without the disease. Approximately 57% of the cost is associated with higher use of nursing home services. Hospital stays also accounted for significant expenditures. According to researchers, Parkinson’s patients incurred approximately 1.9 million hospital inpatient days in 2010, which is 73% more than would be expected for a similar population. Other excess health care usage (as measured for the year 2010) included 1.26 million physician office visits, 57,000 outpatient visits, 31,000 emergency visits, 24,000 home health days, and 26,000 hospice days. Indirect costs, such as loss of employment, were estimated to be $6.3 billion. The authors of the study stress the need for innovative new treatments to prevent, delay onset, or alleviate symptoms.

A related study, published in the same issue of Movement Disorders, examined the economic consequences of slowing the progression of the disease. The study looked at direct and indirect excess costs, and found that the average excess direct costs are $303,754. In a scenario where the progression of disease could be slowed by 20%, researchers found that there would be a $60,657 savings per patient ($75,891 if lost income is included). If the Parkinson’s disease progression were slowed by 50%, there would be a 35% reduction in excess costs. While the cost savings are strongly dependent on the degree to which the progression of the disease can be slowed, it is clear that reducing progression rates could have a significant economic effect. —Ann W. Latner, JD