1. Progression markers of motor deficits in Parkinson's disease: A biannual 4-year prospective study.  Heinzel S, Bernhard FP, Roeben B, Nussbaum S, Heger T, Martus P, Hobert MA, Maetzler W, Berg D. Mov Disord. 2017 Aug;32(8):1254-1256. doi: 10.1002/mds.27062. Epub 2017 Jul 6.

The performance speed of inserting pegs into a pegboard is a robust progression marker of motor deficits in early-stage, but not mid/advanced-stage Parkinson’s disease. Markers that may quantify the progression of symptoms and disease severity are important for determining the efficacy of therapeutic interventions and for the investigation of individual differences in the disease course.

2. Motor dual-tasking deficits predict falls in Parkinson's disease: A prospective study.  Heinzel S, Maechtel M, Hasmann SE, Hobert MA, Heger T, Berg D, Maetzler W. Parkinsonism Relat Disord. 2016 May;26:73-7. doi: 10.1016/j.parkreldis.2016.03.007. Epub 2016 Mar 14.

Simultaneously performing two motor tasks (walking and checking boxes) predict future falls in Parkinson’s disease. These findings may help to inform strategies of fall prevention and may indicate that performance of two motor, but not a cognitive and a motor task, involve a processing bottleneck that is indicative of future falls in Parkinson’s disease.

3. Application of the movement disorder society prodromal Parkinson's disease research criteria in 2 independent prospective cohorts. Pilotto A*, Heinzel S*, Suenkel U*, Lerche S, Brockmann K, Roeben B, Schaeffer E, Wurster I, Yilmaz R, Liepelt-Scarfone I, von Thaler AK, Metzger FG, Eschweiler GW, Postuma RB, Maetzler W, Berg D (2017). Mov Disord. 2017 May 16. doi: 10.1002/mds.27035.

Calculation of individual probabilities of prodromal Parkinson’s disease based on non-motor markers and mild motor signs in participants of two large prospective cohort studies. Only 2 out of 17 incident Parkinson cases fulfilled the criteria of the Movement Disorder Society (MDS) for probable (>80%) prodromal Parkinson’s disease before the PD diagnosis. Yet, while the MDS criteria showed low sensitivity high specificity (>98%) was observed. This manuscript shows that objective and specific markers are needed for a more accurate early detection of Parkinson’s disease.

4. Naturally occurring alpha-synuclein autoantibodies in Parkinson's disease: sources of (error) variance in biomarker assays. Heinzel S, Gold M, Deuschle C, Bernhard F, Maetzler W, Berg D, Dodel R. PLoS One. 2014 Dec 3;9(12):e114566. doi: 10.1371/journal.pone.0114566. eCollection 2014.

Non-replication of previous findings showing lower alpha-synuclein auto-antibody levels in serum of Parkinson’s disease patients compared with healthy controls. In a sample of 69 healthy individuals and 66 Parkinson’s disease patients no significant differences of this marker was found in serum, nor in cerebrospinal fluid. However, various potential sources of (error) variance were identified that may alter the results of the ELISA quantifying the marker levels.

5. Prodromal Markers in Parkinson's Disease: Limitations in Longitudinal Studies and Lessons Learned.  Heinzel S, Roeben B, Ben-Shlomo Y, Lerche S, Alves G, Barone P, Behnke S, Berendse HW, Bloem BR, Burn D, Dodel R, Grosset DG, Hu M, Kasten M, Krüger R, Moccia M, Mollenhauer B, Oertel W, Suenkel U, Walter U, Wirdefeldt K, Liepelt-Scarfone I, Maetzler W, Berg D (2016). Front Aging Neurosci. 2016 Jun 22; 8:147, Review.

A systematic review of 35 longitudinal studies on prodromal Parkinson’s disease and assessment of their evidence-level criteria and limitations. Differences in study design and diagnostic criteria are discussed and limitations, e.g. in marker assessment, sample size and consideration of confounders, such as age, are systematically assessed. Conclusions are drawn for data analyses and cooperation/comparability of cohorts while designs of future studies are suggested.