Dr Jellinger's results complement our findings of rapid motor decline in patients with PD who have old-age onset and extend our findings by reporting shortened survival rates as well. Most of his comments focus on the high frequency of coexistent dementia and neuropathologic findings of AD in this group. We did not systematically evaluate cognitive function in our series, although major dementia was probably not a prevalent feature among our patients. They were able to return to our tertiary care center specifically for the treatment of PD, and their medical records contained no mention of dementia even though the treating physicians were all movement disorder specialists aware of the potential for cognitive decline in PD. When we statistically removed the confounding influences of comorbidities from our analysis, the subjects with old-age onset still showed a more rapid progression in motor impairment than the patients with younger-onset PD. These data convince us that old age per se influences the progression of parkinsonism. Our findings are largely confirmed by Papapetropoulos and colleagues. Interestingly, these authors confirmed physicians' reluctance to prescribe a dopamine agonist as monotherapy to patients with PD and old-age onset in another medicocultural environment. Their data confirm our own impression that dementia is neither a statistically significant comorbidity nor an outcome confounder in patients with PD who have old-age onset.
Diederich NJ, Moore CG, Leurgans SE, Chmura TA, Goetz CG. Clinical Characteristics of Late-Onset Parkinson Disease—Reply. Arch Neurol. 2003;60(12):1816. doi:10.1001/archneur.60.12.1815