Corinne Self, MD, Department of Medicine, University of Arizona College of Medicine

November 2016

Parkinson's disease (PD) is a neurodegenerative disorder that affects 1-2% of people over age 60. Onset is typically after age 55; the average age at diagnosis is 70. Disability usually occurs 3-7 years after diagnosis, but the course is quite variable and some patients have the disease for a decade or more without disability. In late stages of PD, patients may have difficulty completing activities of daily living and trouble swallowing. The risk of death is 2-5x higher in patients with PD than in age-matched peers. Ongoing goals of care discussions are a key part of management. 

PD is caused by degeneration of neurons in the basal ganglia with resulting dopamine deficiency. Why these changes occur is unknown, although there are some familial cases in which genetic mutations have been identified. Parkinsonism is a general  term describing a patient with rest tremor, rigidity, bradykinesia and postural instability. Although most often caused by idiopathic neurodegeneration, parkinsonism may be due to toxins, medications, and structural changes such as stroke or normal pressure hydrocephalus.

Although the disease is most well-known for motor impairments such as tremor, limb rigidity, and slow movement, it causes many other debilitating  symptoms. They include falls, cognitive impairment, depression, urinary incontinence, orthostatic hypotension, and others.

Diagnosis

PD is a clinical diagnosis. Early signs and symptoms may include a subtle one-sided rest tremor, decreased arm swing, loss of facial expression, hypophonia (soft voice), loss of dexterity and small handwriting. It can progress to classical stooped posture, freezing gait and festination. There are no lab or imaging tests that definitely confirm the presence of PD. When the diagnosis is uncertain, a dopamine transporter (DaT) scan can help confirm the diagnosis.

Treatment

There is no cure for PD, but  several medical, surgical, and physical therapies can improve symptoms. Unfortunately, there are ethnic/racial disparities in the diagnosis and treatment of PD, including enrollment in clinical trials.

Medical Therapy

Several medications can improve motor and non-motor symptoms. Patients with idiopathic PD have a robust response to a trial of levodopa, the first-line treatment for motor symptoms. It is typically administered in combination with carbidopa to limit peripheral activity of the drug relative to activity in the brain.

But, even with combination levodopa/carbidopa, patients may experience involuntary movements, hallucinations, compulsive behaviors, hypotension, and other symptoms. Furthermore, as PD progresses, higher doses of levodopa are needed, and with higher doses and prolonged use, patients sometimes develop "on-off" fluctuations, in which medication effects suddenly wear off.

For patients with symptoms not adequately controlled with levodopa, adjunctive medications can be used (Table 1).

For non-motor symptoms, a number of treatments are used and provide variable benefit (Table 2).

Drugs to avoid in PD include anti-emetics, metoclopramide, prochlorperazine, promethazine, and antipsychotics (except aripiprazole, quetiapine, clozapine).

Surgical Therapy

In addition to medications, a procedure called deep-brain stimulation (DBS) can be helpful in certain cases. It involves surgically implanting electrodes in parts of the brain affected by PD to reduce motor symptoms. Deep brain stimulation should be considered for patients who are initially responsive to levodopa, but whose symptoms are not adequately controlled with medical therapy and who have failed several classes of medications. Symptoms most likely to improve with DBS are tremor, on-off fluctuations, and involuntary movements.

Falls in Parkinson's Disease

Movement disorders, muscle restrictions, and reduced balance are all common in PD and can lead to falls. Physical and occupational therapists can address these limitations by teaching new movement techniques, compensatory strategies, and use of adaptive equipment. In addition to the potential to improve strength, flexibility, and balance, PD patients and families find the group support and encouragement valuable. Of note, Tai Chi has been shown to improve postural stability and reduce falls in patients with PD.

Cognition in Parkinson's Disease

Cognitive impairment is common in PD; 40-80% of patients eventually develop dementia. The risk increases with duration of illness and older age. In contrast to Alzheimer's disease, patients with PD dementia most commonly have deficits in attention, processing speed, executive  functions, and visual-spatial function while language skills are preserved. And, while patients may have difficulty with information retrieval, severe memory loss does not occur. Clinicians should monitor for cognitive decline and facilitate financial planning and early completion of advanced directives. Cholinesterase inhibitors such as donepezil and rivastigmine are effective in PD dementia, resulting in moderate improvements in cognition and hallucinations.

Depression and Parkinson's Disease

Depressive symptoms occur in up to half of PD patients, and major depression in 10-20%. However, some patients appear to be depressed because they have difficulty with initiating behaviors (i.e., "they just sit there"). Patients should be routinely screened for depression, but the aforementioned behavior should be distinguished from true depression. Although there is no clear consensus about the best treatment, sertraline may be beneficial and less apt to aggravate motor symptoms than other SSRIs. Ropinirole and pramipexole have also been shown to improve depressive symptoms. They may be used instead of or in combination with levodopa, though treatment of depression is an off-label use. These drugs are also effective for treating restless leg syndromes in patients with PD.

References and Resources

• National Institute of Neurological Disorders and Stroke   
• National Parkinson Foundation  
• Okun OS. Deep-brain Stimulation for Parkinson's Disease. N Engl J Med 2012;367:1529-38.
• Long AE, Lozano AM Parkinson's Disease. J Engl J Med 1998;339:1044-1053.
• Tarsy D. Management of comorbid problems associated with Parkinson disease. UpToDate. 2016.

Interprofessional care improves the outcomes of older adults with complex health problems

Elder Care Editors: Editor-in-Chief: Barry D Weiss, MD;  Deputy Editor: Mindy Fain, MD
 
 National Editorial Board: Theodore M Johnson II, MD, MPH, Emory University; Jenny Jordan, PT, DPT, Sacred Heart Hospital, Spokane, WA;  Jane Marks, RN, MS, FNGNA, Johns Hopkins University; Josette Rivera, MD, University of California San Francisco; Jean Yudin, CRNP, University of Pennsylvania
 
 Interprofessional Associate Editors: Carleigh High, PT, DPT; David Coon, PhD; Marilyn Gilbert, MS, CHES; Jeannie Lee, PharmD, BCPS; Marisa Menchola, PhD;  Francisco Moreno, MD; Linnea Nagel, PA-C, MPAS; Lisa O'Neill, DBH, MPH; Floribella Redondo; Laura Vitkus, MPH, CHES

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 This project was supported by the Health Resources and Services Administration (HRSA) of the U.S. Department of Health and Human Services (HHS) under grant number U1QHP28721, Arizona Geriatrics Workforce Enhancement Program.   This information or content and conclusions are those of the author and should not be construed as the official position or policy of, nor should any endorsements be inferred by HRSA, HHS or the U.S. Government.