Defining the Parkinson's disease phenotype: initial symptoms and baseline characteristics in a clinical cohort.

OBJECTIVES Examine the demographic and historical characteristics of a large Parkinson's disease (PD) clinical cohort and determine the pattern and relationship between initial symptoms of PD and physical examination ratings at the initial subspecialty clinic visit. METHODS A clinical series of 1244 consecutive individuals diagnosed with PD. Baseline characteristics were examined. RESULTS The overall sample was predominantly right-handed (92%) male (67%), with a mean age of 70 years and symptomatic disease duration of about 7 years. About 25% of the sample reported a positive family history of a neurodegenerative disorder. Tremor (47%) and bradykinesia (29%) were the two most common initial symptoms of PD and occurred primarily in the upper extremities (68%). Tremor, bradykinesia, and postural instability showed a significant correspondence between the initial self-reported symptom and clinical signs at the first exam p < 0.05. However, rigidity did not show a significant correspondence. CONCLUSION The demographic and clinical characteristics of the sample are thought to be phenotypically representative of 'typical' PD and were comparable to other clinic- and population-based cohorts. Initial symptoms reported by patients, including type and body location correlate tightly with initial examination findings for all cardinal symptoms of parkinsonism except rigidity. This corroboration may substantiate inclusion of such data in studies of longitudinal progression in PD.