Bradykinesia, upper limb dysfunction, cognitive change and postural instability are established features of Parkinson’s Disease at diagnosis. However it is unknown when during the prodromal disease course they begin. Abnormal quantitative motor testing and cognitive deficits are associated with increased Parkinson’s Disease risk although assessment methods and outcomes vary. Understanding how and when these deficits develop will improve early detection and clarify prodromal disease course.

The UK Biobank dataset includes 500,000 adults recruited at age 40-69 between 2006-2010. Ongoing follow-up includes repeat testing, death registry and diagnostic coding based on electronic health records. We analysed demographics, medical history, cognitive function and physical measures in those who were diagnosed with Parkinson’s Disease after recruitment, and age/sex matched controls. Those with a diagnosis of Parkinson’s Disease at baseline were excluded.

2212 cases of Parkinson’s Disease were identified (male= 62%, mean age 63.8±5.2 years, mean time from assessment to diagnosis 7.7±2.7 years). 357/2212 (male=70%) had died by May 2020 (mean assessment to death 9.4±2.2 years). At baseline, those who later developed Parkinson’s Disease already had more falls (p<0.0001), slower mean reaction time (p<0.0001), weaker handgrip strength (p<0.0001) and more errors in matching pairs (p<0.0001) than controls. Self-rated health assessments of “Fair” (hazard ratio 1.18, p=0.035) or “Poor” (hazard ratio 1.31, p=0.013) were predictive of a shorter time to diagnosis of Parkinson’s Disease. Men had increased risk of death (hazard ratio 1.40, p=0.04). Baseline numeric memory, fluid intelligence, prospective memory and weight did not differ between groups. 

There are changes in balance, motor control and perceived health even at an average of 7 years prior to diagnosis of Parkinson’s Disease. Recognition of prodromal Parkinson’s Disease may improve early diagnosis and the efficacy of future disease-modifying treatments.