Prediagnostic markers of idiopathic Parkinson's disease: Gait, visuospatial ability and executive function

Background: Idiopathic Parkinson's disease (IPD) has a long preclinical phase. Research question: This study assesses data on prediagnostic markers of IPD from a longitudinal, natural history study of aging. Methods: Participants were selected from the database of the Baltimore Longitudinal Study of Aging, and included 10 prediagnosed IPD cases (eight men and two women) and 30 age and sex matched healthy controls. Patients with prediagnosed IPD had already had an assessment for IPD 2.6 +/- 1.3 years (range 1.0-5.3 years) before the actual diagnosis, including: gait speed (six-meter corridor walk), spatio-temporal gait parameters using Vicon motion capture, balance, upper-limb motor skills, neuropsychological profile, and non-motor symptoms. Results: Prediagnosed IPD cases compared to controls had slower gait speed (Delta=-0.13 m.s(-1), p = 0.03) due to shorter step length (Delta= -5 cm, p = 0.004), worse visuospatial ability (card rotation test, Delta=-42, p = 0.0001) and worse executive function (category fluency test, Delta=-2.6, p = 0.04). Significance: Our findings identify dimensions that merit further study as prediagnostic markers of Idiopathic Parkinson's disease to identify patients who might benefit from future neuroprotective therapy in order to delay, or prevent, clinical manifestations.