Pacific Northwest Udall Center of excellence clinical consortium: study design and baseline cohort characteristics

Abstract

Background: The substantial proportion of individuals with Parkinson's disease (PD) who have or are expected to develop concomitant cognitive impairment emphasizes the need for large, well-characterized participant cohorts to serve as a basis for research into the causes, manifestations, and potential treatments of cognitive decline in those with PD.

Objective: To establish a multi-site clinical core that cognitively and clinically characterizes patients with PD by obtaining quality longitudinal clinical, neuropsychological, and validated biomarker data.

Methods: Six hundred nineteen participants with idiopathic PD (68.0 ± 9.1 years, 7.1 ± 6.2 years since diagnosis, 70% males) were enrolled in the Pacific Northwest Udall Center (PANUC), one of the Morris K. Udall Centers of Excellence for Parkinson's Research, Clinical Consortium and underwent comprehensive clinical and neuropsychological assessment. Participants were diagnosed with no cognitive impairment (PD-NCI), mild cognitive impairment (PD-MCI), or dementia (PDD) at a diagnostic consensus conference.

Results: A substantial proportion of the overall sample was diagnosed with cognitive impairment at baseline: 22% with PDD and 59% with PD-MCI. A higher rate of cognitive impairment was observed in men than women (87% vs. 68%, p < 0.0001), despite a higher level of education. Most patients older than 50 years at the time of diagnosis and with disease duration greater than 10 years were cognitively impaired or demented.

Conclusions: The PANUC Clinical Consortium is a clinically and cognitively well-characterized cohort of patients with PD. Baseline cohort characteristics demonstrate a high rate of cognitive impairment in the sample, as well as potential sex differences with regard to cognitive diagnosis. The PANUC Clinical Consortium, with its access to biomarker, genetic, and autopsy data, provides an excellent foundation for detailed research related to cognitive impairment in PD.

Figure 1

PANUC Clinical Consortium cognitive diagnoses by study site.

Figure 2

Panel A shows the frequency distribution of age at diagnosis of PD for PANUC consortium subjects stratified by cognitive status at time of entry into PANUC. Panel B shows the frequency distribution for duration of PD at the time of entry into PANUC. Panel C shows the plot of age at PD diagnosis vs. duration of PD for subjects stratified by cognitive status. Dashed lines establish age and duration cutoffs that define four groups. Fisher's exact test for the four groups of cognitively normal PD subjects had p < 0.0002.