Table 3.
Comparing the K-means Clusters’ Descriptive, Clinical, and Cognitive Characteristics.
| Characteristic Measure |
Cluster 1 Cognitively Average |
Cluster 2 Low EF |
Cluster 3 Prominently Impaired EF/Memory |
Omnibus Kruskal– Wallis H-Test |
Effect Size | Post hoc Differences (Bonferroni Corrected) |
|---|---|---|---|---|---|---|
| N = 154 | N = 227 | N = 113 | ||||
| Mean (SD)/ | Mean (SD)/ | Mean (SD)/ | p-value | Eta squared /Cramer’s V # | ||
| % | % | % | ||||
| Age (years) | 64.51 (8.75) | 65.31 (9.12) | 63.85 (9.15) | 0.38 | 0.004 | -- |
| Education (years) | 15.35 (2.55) | 14.91 (2.91) | 14.73 (2.83) | 0.13 | 0.01 | -- |
| Sex (% Male) | 68% | 73% | 75% | 0.33 ^ | 0.07 # | -- |
| % Caucasian, Non | 99% | 93% | 91% | 0.01 ^ | 0.15 # | 1 < [2 = 3] * |
| Hispanic | ||||||
| % H-Y Stages 2–3 | 95% | 93% | 95% | 0.57 ^ | 0.06 # | - |
| % Tremor Subtype | 73% | 76% | 82% | 0.16 ^ | 0.08 # | -- |
| Years Since Symptom | 9.45 (5.14) | 9.51 (5.20) | 10.03 (5.57) | 0.58 | 0.002 | -- |
| Onset | ||||||
| Years Since Diagnosis | 7.70 (5.06) | 7.58 (4.73) | 8.56 (5.15) | 0.23 | 0.01 | -- |
| UPDRS Part III | 22.78 (8.85) | 25.18 (9.38) | 28.91 (10.81) | <0.001 | 0.05 | [1 = 2] < 3 ** |
| BDI-II | 9.15 (7.04) | 9.81 (6.06) | 12.09 (7.79) | 0.001 | 0.03 | 1 < 3 ** |
| Apathy Scale | 10.47 (6.33) | 10.89 (6.25) | 13.01 (6.14) | 0.01 | 0.02 | [1 = 2] < 3 ** |
| STAI: State Pct. | 53.20 (31.34) | 63.26 (28.51) | 68.73 (28.09) | <0.001 | 0.04 | 1 < [2 = 3] ** |
| STAI: Trait Pct. | 50.11 (31.29) | 59.21 (30.30) | 68.33 (27.73) | <0.001 | 0.04 | 1 < 2 < 3 ** |
| DRS-2 | 139.54 (3.10) | 136.92 (4.22) | 133.65 (4.42) | <0.001 | 0.23 | 1 > 2 > 3 * |
| Cognitive Domain | ||||||
| Z-Score Composites | ||||||
| Executive Function | 0.20 (0.59) | −0.58 (0.58) | −1.63 (0.65) | <0.001 | 0.56 | 1 > 2 > 3 * |
| Memory | 0.51 (0.70) | −0.44 (0.75) | −1.40 (0.75) | <0.001 | 0.47 | 1 > 2 > 3 * |
| Language | 0.79 (0.68) | −0.08 (0.70) | −1.02 (0.72) | <0.001 | 0.48 | 1 > 2 > 3 * |
| Visuospatial Skills | 0.44 (0.56) | 0.01 (0.70) | −0.59 (0.82) | <0.001 | 0.21 | 1 > 2 > 3 * |
| Attention/WM | 0.67 (0.70) | 0.03 (0.72) | −0.20 (0.63) | <0.001 | 0.20 | 1 > 2 > 3 ** |
Note. * Significant difference at p < 0.001 across all group comparisons; ** Significant difference at p < 0.05 across all group comparisons; ^ Chi-square test of independence used; # Cramer’s V values; EF = Executive Function; WM = Working Memory; H-Y = Hoehn and Yahr; UPDRS = Unified Parkinson’s Disease Rating Scale; BDI-II = Beck Depression Inventory-II, STAI = State-Trait Anxiety Inventory; DRS-2 = Dementia Rating Scale-2.