CAN THE COURSE OF PARKINSON’S DISEASE BE PREDICTED?
We are making progress. Standard teaching is that patients with mainly tremor, so-called tremor-dominant Parkinson’s, and younger age of onset do better. Patients with older age of onset and initial symptoms of stiffness and slowness of movement and walking do worse. Newer studies show that this distinction is too simplistic.
In fact, there are 3 symptoms that when present at the initial visit are the defining features leading to a “malignant” subgroup. These are:
1. Orthostatic hypotension (OH), meaning a fall of systolic blood pressure of 10 points from sitting to standing which may or may not cause lightheadedness.
2. Mild cognitive impairment (MCI).
3. Rapid dreams movement sleep behavior disorder (RBD). These patients “act out” dream and often yell, kick, punch during sleep and may in fact fall out of bed and have serious injuries.
The patients in the “malignant” group usually have OH, MCI, RBD but also have severe motor symptoms, including impaired gait and frequent falls.
The group with the best prognosis may have prominent tremor, but they do not have OH, less frequently have RBD, and moderately have MCI. The intermediate group does not have cognitive impairment but may have OH and RBD. It is also possible that each of the 3 subtypes may only represent a stage in the evolution of the disease.
Being able to offer prognosis with some degree of confidence is obviously important in counseling patients and families. It is also important in that when patients enter clinical trials, they may be “stratified,” and this increases the validity of the results.
Jack Florin, MD
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