Parkinson's disease (PD) is typically thought to be a disorder of the elderly. The average age of onset for Parkinson's disease (PD) is approximately 58 years in the U.S. and elsewhere. However, the first symptoms (such as tremor, slowed movement, or decreased dexterity) can arise much earlier in life; some cases of PD have clearly developed up to three decades earlier than its typical age of onset. Most estimates indicate that no more than 5-10% of PD cases begin under the age of fifty. When patients develop PD in this age range (sometimes as early as in their twenties or thirties), this is generally referred to as "young-onset PD". Though distinguished by its age of onset, this disorder appears in most respects to be identical to PD beginning at an older age. The clinical features and response to medications do not differentiate it from development of PD in the elderly. The loss of nerve cell generating dopamine in the brain is the same for both younger- and older-onset PD. There are some differentiating characteristics, however. PD beginning under the age of 50 has less of a tendency to develop concomitant cognitive impairments or dementia than when the disorder begins in older years. There may be an increased tendency for the chronic use of levodopa to result in involuntary movements (dyskinesias) in the young-onset patient.
The disabilities of young-onset PD differ from problems experienced from the same disorder beginning later in life. The impact of young-onset PD affects a patient's livelihood, family roles, friendships, and enjoyment of life in sometimes a more extreme manner than for an older person, who might be retired from work and unburdened with young children. It is obvious from discussions at support groups involving young-onset patients that their daily struggle with PD is often quite different from that experienced by older subjects. Sometimes the need for a patient to inform his or her young children, employers, and peers about this uncommon occurrence of PD is very challenging. Even for patients affected with relatively mild forms of it, PD has the "persona" of exaggerated aging and physical deterioration. As a result, sometimes work or other activities are unfairly restricted as a result. The tremors often associated with PD can be misinterpreted by others as either anxiety or physical frailty. Difficulties that PD can cause for the ease of communication by voice or handwriting can only add to the "cosmetic" stigma of PD.
Fortunately, the same drugs and other treatment options useful in older patients can be highly effective in young-onset PD. Those making use of medications needs to give consideration to the risk for long-term outcomes such as dyskinesias. For this reason, many clinicians believe that levodopa use should either be restricted (if possible) or that a dopaminergic agonist be used together with it. Young-onset PD has an increased risk to be a hereditary disorder. If other first-order family members are also affected with young-onset PD, a search for the very rare genetically mediated forms of PD may be warranted. A young onset of PD also calls for a careful investigation of possible alternative diagnoses. Since several conditions can mimic PD, a thorough examination by a neurological specialist is warranted. This evaluation sometimes uses testing such as an MRI scan of the brain to make a correct diagnosis. Fortunately, most persons even at a young age with Parkinsonism have nothing more than PD. Since many (if not most) people with PD continue to respond well to medications over long periods of time, this disorder is generally deserving of reassurance to the patient from the treating physician.
Peter A. LeWitt, M.D.
Director, Parkinson's Disease and Movement Disorders Program, Henry Ford Hospital
Professor of Neurology, Wayne State University School of Medicine
President, Board of Directors, MPF.
Member and Past Chairman, Professional Advisory Board.
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