The Multiple Object Test as a performance-based tool to assess the decline of ADL function in Parkinson’s disease

<div><p>Introduction</p><p>As cognitive-driven worsening of activities of the daily living (ADL) in Parkinson’s disease (PD) is the core feature of PD dementia (PDD), there is great need for sensitive quantitative assessment. Aim of our study was the evaluation of cognitive-driven worsening of ADL by the performance-based Multiple Object Test (MOT), offering an essential clinical advantage as it is quick and easy to apply in a clinical context even on severely impaired patients.</p><p>Methods</p><p>73 PD patients were assessed longitudinally over a period of 37 (6–49) months. According to their neuropsychological profile the sample was divided into two groups: PD patients with (n = 34, PD-CI) and without cognitive impairment (n = 39, PD-noCI). The MOT comprises five routine tasks (e.g. to make coffee) quick and easy to apply. Quantitative (total error number, processing time) and qualitative parameters (error type) were analyzed using non-parametric test statistic (e.g.Wilcoxon signed-rank test, binary logistic regression).</p><p>Results</p><p>Median number of total errors (p = 0.001), processing time (p<0.001), perplexity (p = 0.035), and omission errors (p<0.001) increased significantly from baseline to follow-up in the total sample. Worsening of MOT performance was correlated to cognitive decline in the attention/ executive function and visuo-constructive domain. PD-CI showed an increase in omission errors (p = 0.027) compared to PD-noCI over time. This increase in omission errors between visits was further identified as a risk marker for PDD conversion.</p><p>Conclusion</p><p>The MOT, especially frequency of omission errors, is a promising tool to rate PD patients objectively and might help to identify patients with a high risk for having mild cognitive impairment or dementia.</p></div

Q-Motor digitomotography device and position of the hand for the index finger tapping assessment.

<p>The hand with palm down is placed on a fixed support surface on a table, with the index finger located above the force transducer surface before the tapping experiments are started.</p

Demographics and clinical characteristics.

<p>Data are presented with median (range) and frequency. Statistical comparisons were performed with the Kruskal-Wallis / Wilcoxon rank sum test, and the Pearson / Fisher’s Exact test, with analyses between single cohorts using Bonferroni correction (controls versus early PD, controls versus mid-stage PD, early PD versus mid-stage PD, <i>p</i> < 0.05/3 = 0.017).</p><p>° Compared to controls</p><p>* Compared to early Parkinson’s disease (PD).</p><p>BDI, Becks Depression Inventory; MMSE, Mini-Mental State Examination; UPDRS III, Motor part of the Unified Parkinson’s Disease Rating Scale.</p><p>Demographics and clinical characteristics.</p

Progression of qualitative MOT parameters.

<p>Comparison of change values (follow-up–baseline) in each Multiple Object Test (MOT) error category between PD patients with (PD-CI) and without (PD-noCI) cognitive impairment.</p

Baseline characteristics of the follow-up cohort, and between-group comparison of Parkinson’s disease patients with (PD-CI) and without (PD-noCI) cognitive impairment.

<p>Baseline characteristics of the follow-up cohort, and between-group comparison of Parkinson’s disease patients with (PD-CI) and without (PD-noCI) cognitive impairment.</p

Correlation of digitomotography measures with clinical data.

<p>Data are calculated with simple regression, and presented with the coefficient of determination (r²).</p><p>* <i>p</i> < 0.05.</p><p>BDI, Becks Depression Inventory; CoV, coefficient of variation; DEV mean, mean tap deviation from the predefined 1.55 Hertz cueing tone; Delta TMT, Trail Making Test part B minus part A, a measure of cognitive flexibility and working memory [<a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0123914#pone.0123914.ref018" target="_blank">18</a>]; DEV SD, variability of tap deviation from the predefined 1.55 Hertz cueing tone; IPI, interpeak interval; MMSE, Mini-Mental State Examination; SD, standard deviation; TF, tap force; UPDRS III, Motor part of the Unified Parkinson’s Disease Rating Scale.</p><p>Correlation of digitomotography measures with clinical data.</p

Comparison of MOT parameters of PD patients with (PD-CI) and without (PD-noCI) cognitive impairment at baseline and follow-up visit.

<p>Comparison of MOT parameters of PD patients with (PD-CI) and without (PD-noCI) cognitive impairment at baseline and follow-up visit.</p

Cognitive diagnosis of patients at baseline and follow-up.

<p>Cognitive diagnosis of patients at baseline and follow-up.</p

Parameters of the Multiple Object Test of follow-up cohort.

<p>Parameters of the Multiple Object Test of follow-up cohort.</p

Inter-assay variability of optical densities (ODs) of α-Syn-nAbs standards measured on plates coated with α-Syn on the same day (assays #1, #2) and coated on different days (assays #3, #4).

<p>Inter-assay variability of optical densities (ODs) of α-Syn-nAbs standards measured on plates coated with α-Syn on the same day (assays #1, #2) and coated on different days (assays #3, #4).</p