Table 3.
Results of cross‐sectional analysis
| Experimental task | Control, N = 53 | PD, N = 52 | P value | Correlation with MDS‐UPDRS item |
|---|---|---|---|---|
| Repetitive finger tapping (RFT) | ||||
| Velocity (v) | ||||
| v mean, cm.s−1 | 24.9 ± 6.2 | 16.1 ± 8.0 | <0.001a | −0.37** |
| Δv, cm.s−2 | −0.22 (−0.43, 0.11)c | −0.29 (−0.51, −0.08)c | 0.14b | 0.03 |
| Frequency (f) | ||||
| f mean, cycles.s−1 | 2.5 ± 0.9 | 2.2 ± 0.8 | 0.027a | −0.24 * |
| Δf, cycles.s−2 | −0.003 (−0.01, 0.02) | −0.01 (−0.03, 0.01) | 0.032b | 0.05 |
| Amplitude (A) | ||||
| A mean, cm | 5.6 ± 1.6 | 4.1 ± 2.0 | < 0.001a | −0.16 |
| ΔA, cm.s−1 | −0.05 (−0.12, 0.01)c | −0.06 (−0.13, −0.01)c | 0.791b | 0.04 |
| Interruptions of rhythm | ||||
| Hesitations, no.cycle−1 | 0.4 (0.2–0.8) | 0.8 (0.3–1.6) | 0.007b | 0.31* |
| Halts, % of time | 0 (0–0) | 0 (0–21.6) | <0.001b | 0.27* |
| Clinical assessment | ||||
| Total MDS‐UPDRS‐III | — | 36.2 ± 16.1 | — | — |
| RFT item 3.4 | — | 2 (1–3) | — | — |
| Alternating hand movements (AHM) | ||||
| Velocity (v) | ||||
| v mean, cm.s−1 | 110.8 ± 37.3 | 84.6 ± 31.3 | <0.001a | −0.41** |
| Δv, cm.s−2 | −0.2 ± 2.0 | −0.7 ± 2.5c | 0.24a | 0.11 |
| Frequency (f) | ||||
| f mean, cycles.s−1 | 1.8 ± 0.6 | 1.5 ± 0.4 | 0.005a | −0.39** |
| Δf, cycles.s−2 | 0.0004 ± 0.03 | −0.005 ± 0.03 | 0.42a | 0.05 |
| Amplitude (A) | ||||
| A mean, cm | 34.2 ± 12.2 | 29.5 ± 9.4 | 0.03a | −0.17 |
| ΔA, cm.s−1 | −0.21 ± 0.62c | −0.35 ± 0.58c | 0.23a | 0.11 |
| Interruptions of rhythm | ||||
| Hesitations, no.cycle−1 | 3.4 (2.9–4.4) | 3.7 (3.2–4.5) | 0.33b | 0.35* |
| Halts, % of time | 0 (0–0) | 0 (0–0) | 0.04b | 0.10 |
| Clinical assessment | ||||
| Total MDS‐UPDRS‐III | – | 36.5 ± 16.6 | – | – |
| AHM item 3.5 | – | 1 (1–2) | – | – |
Δ, change; PD, Parkinson's disease; MDS‐UPDRS‐III, International Parkinson and Movement Disorders Society‐sponsored revision of the Unified Parkinson's Disease Rating Scale.
a
These P values were determined using an independent‐sample t test and parameter values are presented as the mean ± standard deviation.
b
These P values were determined using the Mann‐Whitney U test and parameter values are presented as the median (interquartile range).
c
These values are significantly different from 0 (using the Wilcoxon signed‐rank test; P < 0.05). Asterisks indicate significant correlations between kinematic parameters and the score on the corresponding MDS‐UPDRS item: *P < 0.05; **P < 0.01.