We thank Drs. Bohnen and Muller for their interest in our study on the high incidence of parkinsonism in community-dwelling older adults without PD.1 They note, and we agree, that many factors other than PD pathology contribute to parkinsonian signs in older persons.2,3 Further, Drs. Bohnen and Muller make an excellent point regarding the implications of our findings for aging persons with PD; namely, the factors that contribute to parkinsonism in persons without PD are also likely to contribute to parkinsonism in persons with PD. This may have implications for treatment response and progression of PD. The situation is similar to that of Alzheimer disease (AD). In older persons, mixed pathologies are the most common cause of AD dementia and the coexisting non-AD pathology contributes to both the detection of AD and a more rapid rate of progression.4,5 We agree that physicians need to consider coexisting conditions that make an ever-larger contribution to many diseases with age.
Footnotes
References
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