Table 1. Participant demographic and neuropsychological data by group.
| Variable | Mean (SD), 95% Confidence Interval [Lower, Upper] Range | ||
|---|---|---|---|
| PD | Control | t-tests | |
| Demographic Data | |||
| Age (yrs.) | 68.02 (8.86) [64.28, 71.76] 52–89 | 66.54 (10.85) [61.96, 71.13] 53–87 | t(46) = -0.52, p = 0.608 |
| Education (yrs.) | 17.38 (2.73) [16.66, 18.96] 12–26 | 17.81 (2.72) [16.66, 18.96] 12–23 | t(46) = 0.56, p = 0.581 |
| PTA (better ear) | 21.01 (9.15) [17.15, 24.88] 8.3–35 | 17.89 (6.17) [15.28, 20.49] 5–40 | t(46) = -1.39, p = 0.172 |
| MoCA (/30) | 27.29 (1.63) [26.60, 27.98] 24–30 | 27.08 (1.67) [26.38, 27.79] 24–30 | t(46) = -0.44, p = 0.663 |
| GDS (/15) | 1.79 (2.50) [0.74, 2.85] 0–10 | 0.75 (0.90) [0.37, 1.13] 0–3 | t(28.82)d = -1.92, p = 0.065 |
| Handedness (self-report) | 91.7% Right, 8.3% Left | 87.5% Right, 12.5% Left | - |
| MDS-UPDRS-III (/132)a | 23.7 (11.4) [18.90, 28.56] 6–44 | - | - |
| Hoehn & Yahr (/5)b | 1.77 (0.75) [1.45, 2.09] 1–4 | - | - |
| Years since PD diagnosis | 5.99 (5.49) [3.67, 8.31] .9–25 | - | - |
| Neuropsychological Assessment Data | |||
| D-KEFS Trail Making Test (Switching vs. Number/Letter scaled score) | 9.58 (2.98) [8.33, 10.84] 3–17 | 9.04 (2.10) [8.16, 9.93] 6–13 | t(46) = -0.73, p = 0.470 |
| D-KEFS Color Word Interference Test (Switching vs. Color + Word scaled score) | 10.92 (2.00) [10.07, 11.76] 6–14 | 11.58 (2.41) [10.56, 12.60] 7–16 | t(46) = 1.04, p = 0.303 |
| Digit Span Backwards (scaled score) | 8.78 (2.89) [7.56, 10.00] 3–16 | 8.79 (3.37) [7.37, 10.22] 3–15 | t(46) = 0.01, p = 0.992 |
| Semantic Fluency (Animals, scaled score) | 11.75 (3.14) [10.42, 13.08] 6–19 | 11.00 (2.27) [10.04, 11.96] 7–16 | t(46) = -0.95, p = 0.347 |
| CLOX I (Free-draw scaled score) | 10.96 (1.81) [10.20, 11.72] 6–13 | 11.42 (1.18) [10.92, 11.91] 9–13 | t(39.55)d = 1.04, p = 0.304 |
| CLOX II (Copy trial scaled score) | 9.17 (2.87) [7.96, 10.38] 1–12 | 9.38 (3.46) [7.91, 10.84] 3–12 | t(46) = 0.23, p = 0.821 |
| Boston Naming Test (/30) | 27.67 (2.24) [26.72, 28.61] 22–30 | 28.13 (2.33) [27.14, 29.11] 22–30 | t(46) = 0.70, p = 0.491 |
| Northwestern Naming Battery (/31) | 30.74 (0.53) [30.52, 30.97] 29–31 | 30.75 (0.68) [30.46, 31.03] 28–31 | t(46) = 0.02, p = 0.984 |
| NAVS sentence comprehension (/30) | 29.88 (0.34) [29.73, 30.02] 29–30 | 29.75 (0.53) [29.53, 29.97] 28–30 | t(38.97)d = -0.97, p = 0.337 |
| Pyramids and Palm Trees (/14) | 13.92 (0.28) [13.80, 14.04] 13–14 | 13.96 (0.20) [13.87, 14.04] 13–14 | t(46) = 0.59, p = 0.561 |
| HVLT-R total recall (t-score) | 47.38 (9.16) [43.51, 51.24] 30–66 | 49.67 (7.19) [46.63, 52.70] 32–64 | t(46) = 0.96, p = 0.340 |
| BVMT-R total recall (t-score)e | 52.83 (9.06) [49.01, 56.66] 34–68 | 53.96 (14.85) [47.69, 60.23] 20–73 | t(38.1)d = 0.32, p = 0.753 |
Note. PTA = Pure Tone Average (of 500, 1000, and 2000 Hz). MoCA = Montreal Cognitive Assessment. GDS = Geriatric Depression Scale. D-KEFS = Delis-Kaplan Executive Function System. NAVS = Northwestern Assessment of Verbs and Sentences. HVLT-R = Hopkins Verbal Learning Test- Revised. BVMT-R = Brief Visuospatial Memory Test-Revised.
aAll PD participants were assessed using the Unified Parkinson’s Disease Rating Scale motor section (MDS-UPDRS-III; [109]) and the modified Hoehn and Yahr Scale [110] by a certified examiner. The UPDRS-III is a standardized measure of motor impairment in PD and assesses tremor, slowness (bradykinesia), stiffness (rigidity), and balance.
bThe Hoehn and Yahr Scale is a standardized measure of disease severity, with scores ranging from 0 (asymptomatic) to 5 (wheelchair-bound).
c Calculated by averaging participants’ scaled scores from: digit span backwards, D-KEFS trail-making test switching versus composite number and letter sequencing, D-KEFS color-word inhibition test switching versus composite color and word reading, semantic fluency, and CLOX I [112]. Scaled scores for the semantic fluency and CLOX I tests were converted from t-scores and z-scores, respectively.
dlower d.f. due to Welch’s test for unequal variances
eBVMT-R normative values for participants aged 80–89 were drawn from Gale, Baxter, Connor, Herring, and Comer (2007)