Parkinson disease with old-age onset - A comparative study with subjects with middle-age onset

Background: To our knowledge, no prior study has focused on subjects with Parkinson disease (PD) with elderly disease onset, and there is little evidence-based knowledge of treatment outcomes in these patients. Objective: To compare the clinical presentation, co-morbidities, treatment, and evolution of PD in patients with old-age onset with those of patients with middle-age onset in one US university center. Design: In the Rush Movement Disorder Database, we retrieved 43 patients with PD with onset at 78 years or older. By using a case-control design, we assigned each patient with old-age PD onset 1 (n = 5) or 2 (n = 38) patients with middle-age PD onset, matched for disease duration but with disease onset between the ages of 43 and 66 years. We compared the groups on several clinical measures using conditional logistic regression. Results: At a comparable length of PD duration (mean, 5.1 years for patients with old-age PD onset and 5.5 years for patients with middle-age PD onset), the total Unified Parkinson's Disease Rating Scale motor score was significantly higher in those with old-age PD onset than in those with middle-age PD onset (33.3 vs 21.2; P<.001). The patients with old-age onset had higher scores for rigidity (5.2 vs 4.3; P=.03), bradykinesia (13.0 vs 9.6; P=.001), and axial impairment (12.8 vs 5.2; P<.001), but not for tremor (2.2 vs 2.0; P=.68). They were more likely to have at least one comorbid condition compared with patients with middle-age onset (24 [56%] of 43 patients vs 20 [25%] of 81 patients; P=.002), but even when adjusting for comorbidities, they still maintained higher motor scores than controls. When treating patients with old-age PD onset, clinicians used levodopa monotherapy more frequently than in patients with middle-age PD onset (34 patients [79%] vs 16 patients [20%]; P<.001), and agonists were prescribed less frequently (5 patients [12%] vs 29 patients [36%]; P=.005). Conclusions: At the same disease duration, patients with old-age PD onset have greater motor impairment than patients with middle-age PD onset. This difference may be due to more rapid disease progression, less aggressive or less potent medical treatment, the elderly age of the subjects with old-age PD onset at study end independent of disease onset, or yet-to-be elucidated influences of comorbid conditions. Focused research on old-age PD onset is important to delineate the confounding influences of aging and comorbidities and to establish the safety and efficacy of new treatments for this group of patients.