Background There are currently no treatments that stop or slow the progression of Parkinson's disease (PD). Case–control genome‐wide association studies have identified variants associated with disease risk, but not progression. The objective of the current study was to identify genetic variants associated with PD progression. Methods We analyzed 3 large longitudinal cohorts: Tracking Parkinson's, Oxford Discovery, and the Parkinson's Progression Markers Initiative. We included clinical data for 3364 patients with 12,144 observations (mean follow‐up 4.2 years). We used a new method in PD, following a similar approach in Huntington's disease, in which we combined multiple assessments using a principal components analysis to derive scores for composite, motor, and cognitive progression. These scores were analyzed in linear regression in genome‐wide association studies. We also performed a targeted analysis of the 90 PD risk loci from the latest case–control meta‐analysis. Results There was no overlap between variants associated with PD risk, from case–control studies, and PD age at onset versus PD progression. The APOE ε4 tagging variant, rs429358, was significantly associated with composite and cognitive progression in PD. Conditional analysis revealed several independent signals in the APOE locus for cognitive progression. No single variants were associated with motor progression. However, in gene‐based analysis, ATP8B2, a phospholipid transporter related to vesicle formation, was nominally associated with motor progression (P = 5.3 × 10−6). Conclusions We provide early evidence that this new method in PD improves measurement of symptom progression. We show that the APOE ε4 allele drives progressive cognitive impairment in PD. Replication of this method and results in independent cohorts are needed. © 2020 The Authors. Movement Disorders published by Wiley Periodicals LLC on behalf of International Parkinson and Movement Disorder Society

Background: There are currently no treatments that stop or slow the progression of Parkinson's disease (PD). Case-control genome-wide association studies (GWASs) have identified variants associated with disease risk, but not progression. Objective: To identify genetic variants associated with PD progression in GWASs. Methods: We analysed three large, longitudinal cohorts: Tracking Parkinson's, Oxford Discovery, and the Parkinson's Progression Markers Initiative. We included clinical data for 3,364 patients with 12,144 observations (mean follow-up 4.2 years). We used a new method in PD, following a similar approach in Huntington's disease, where we combined multiple assessments using a principal components analysis to derive scores for composite, motor, and cognitive progression. These scores were analysed in linear regressions in GWASs. We also performed a targeted analysis of the 90 PD risk loci from the latest case-control meta-analysis. Results: There was no overlap between variants associated with PD risk, from case-control studies, and PD age at onset versus PD progression. The APOE ϵ4 tagging variant, rs429358, was significantly associated with the rate of composite and cognitive progression in PD. No single variants were associated with motor progression. However in gene-based analysis, variation across ATP8B2, a phospholipid transporter related to vesicle formation, was nominally associated with motor progression (p=5.3 x 10^-6). Conclusions: This new method in PD improves measurement of symptom progression. We provide strong evidence that the APOE ϵ4 allele drives progressive cognitive impairment in PD. We have also reported loci of interest which need to be tested in further studies.

Background: L-dopa responsiveness in Parkinson's disease (PD) varies, but the clinical correlates and significance of this are ill-defined. Methods: Patients were assessed before and after their usual morning L-dopa dose, using the MDS Unified PD Rating Scale Part 3 (MDS UPDRS 3), and rated as definite responders (≥24.5% improvement) or limited responders (<24.5%). Results: 1007 cases, mean age 66.1 years (SD 9.1) at diagnosis, were assessed 3.4 (SD 0.9) years after diagnosis. The L-dopa response was definite in 614 cases (61.0%), median reduction in MDS UPDRS 3 scores was 42.0%, (IQR 33.3, 53.1), and was limited in 393 cases (39.0%), median reduction in MDS UPDRS 3 scores 11.5% (IQR 4.3, 18.2). Definite responders were younger (66.3 years at study entry, SD 9.3) than limited responders (69.2 years, SD 8.4, p<0.001). The MDS UPDRS 3 score at study entry in definite responders (21.0, SD 10.5) was significantly lower than in limited responders (24.7, SD 13.4, p<0.001). The MDS UPDRS 3 increase over 18 months was less in definite responders at 3.0 (SD 10.4), compared to limited responders (6.4, SD 11.0, p<0.001). The levodopa equivalent daily dose (LEDD) was not significantly different at study entry (definite responders 317mg, SD 199, vs limited responders 305mg, SD 191, p=0.53). However, LEDD was significantly higher at the time of the L-dopa challenge test in definite responders (541mg, SD 293) compared to limited responders (485mg, SD 215, p=0.01). Responsiveness to L-dopa was unaffected by the challenge test dose (p=0.54). Conclusions: The main determinants of variation in the L-dopa response in early PD are age and motor severity. A limited L-dopa response is associated with faster motor progression.

A BS TRACT: Background: Clinical diagnosis and monitoring of Parkinson's disease (PD) remain challenging because of the lack of an established biomarker. Neuromelanin-magnetic resonance imaging (NM-MRI) is an emerging biomarker of nigral depigmentation indexing the loss of melanized neurons but has unknown prospective diagnostic and tracking performance in multicenter settings. Objectives: The aim was to investigate the diagnostic accuracy of NM-MRI in early PD in a multiprotocol setting and to determine and compare serial NM-MRI changes in PD and controls.

Background Hyposmia is an early feature in neurodegenerative diseases, most notably Parkinson's disease (PD). Using abbreviated smell tests could provide a cost‐effective means for large‐scale hyposmia screening. It is unclear whether short smell tests can effectively detect hyposmia in patient populations. Objectives To test the ability of short smell combinations to “prescreen” for probable hyposmia in people with PD and target administration of more extensive tests, such as the University of Pennsylvania Smell Identification Test. Methods We assessed the screening performance of a short 4‐smell combination previously derived from use of the 40‐item University of Pennsylvania Smell Identification Test in healthy older people and its ability to detect hyposmia in a large cohort of PD patients. Results The novel 4‐smell combination included menthol, clove, onion, and orange and had a sensitivity of 87.1% (95% confidence interval, 84.9%–89.2%) and specificity of 69.7% (63.3%–75.5%) for detecting hyposmia in patients with PD. A different (also novel) 4‐item combination developed using a data‐driven approach in PD patients only achieved 81.3% (78.2%–84.4%) sensitivity for equivalent specificity. Conclusions A short 4‐smell combination derived from a healthy population demonstrated high sensitivity to detect those with hyposmia and PD.