The full research data are provided in Additional file 1.
Group matching, compliance, and success of participant blinding
The groups had comparable baseline patient characteristics (Table 2; individual patient characteristics provided in Supplementary Tables 1 and 2 in Additional file 2). There were no baseline differences on the New Freezing of Gait questionnaire; Falls Efficacy Scale; Activities-specific Balance Confidence Scale; mobility, Activities of Daily Living, or total scores on the Parkinson’s Disease Questionnaire 39; or the Patient Centered Outcomes Questionnaire for Parkinson’s Disease (ps > .094). The groups did not differ in the number of training sessions completed; or self-rated attention, fatigue, and effort during treatment (ps ≥ .217). There was no difference in the percentage of people in each group who chose “sham”, “real” or “no idea” when asked to guess the treatment that they had been assigned to in the post-treatment session [Sham group: 54% / 31% / 15%; Real group: 37.5% / 37.5% / 25%; Χ2 (2) = 3.8, p = .149]. For those patients who guessed sham or real, the confidence (%) of their guesses were not different between the groups (guessed Sham: M = 68.8, SEM = 4.5; guessed Real: M = 78.5, SEM = 6.3; t(19) = 1.3 p = .216). No participants reported any harms or unintended effects.
Table 2
Baseline demographic and clinical characteristics at baseline, split by group.
| Real† | Sham† | Comparison |
N | 16 | 13 | |
Sex (% females) | 31.3 | 53.8 | #p = .19 |
Age (years) | 70.8 (7.9) | 68.3 (8.2) | t(27) = 0.83, p = .41 |
Handedness (% left) | 0.0 | 23.1 | Χ2(29) = 4.1, p = .042* |
Time since diagnosis (years) | 7.5 (5.8) | 7.7 (5.3) | t(27) = 0.14, p = .89 |
Weight (pounds) | 171.0 (58.5) | 159.9 (38.2) | t(27) = 0.59, p = .56 |
Height (inches) | 66.6 (4.4) | 66.5 (5.1) | t(27) = 0.01, p = .99 |
MOCA (/30) | 24.7 (0.5) | 26.5 (3.0) | t(27) = 1.5, p = .15 |
MDS-UPDRS-III | | | |
Gait (/4) | 1 (1) | 1 (2) | U(29) = 84.5, p = .31 |
Freezing (/4) | 0 (1) | 1 (0.5) | U(29) = 87.5, p = .48 |
Postural stability (/4) | 1 (.75) | 1.0 (1.0) | U(29) = 83, p = .37 |
Total (/132) | 34.3 (9.9) | 33.5 (14.7) | t(27) = 0.12, p = .87 |
Hoehn and Yahn | 2.25 (1) | 2.5 (1) | U(29) = 89.5, p = .53 |
TUAG (s) | 11.6 (5.0) | 9.9 (3.0) | t(27) = 0.93, p = .26 |
Abbreviations: MDS-UPDRS-III, Movement Disorder Society Unified Parkinson’s Disease Rating Scale section three; MOCA, Montreal Cognitive Assessment; TUAG, Timed Up and Go. †Summary statistics indicate percentage, mean (standard deviation), or median (interquartile range). #Fisher’s exact test. *significant. |
Questionnaire return rate was higher than 87% across all five testing points, and higher than 97% for the pre and 1d post test. Of the questionnaires that were returned, missing data due to incomplete items were negligible (9 data points across five questionnaires). Missing data were replaced with the group mean for that item. One patient (VA32) arrived late for the 1d post test, leaving insufficient time to run assessments for the Berg Balance Scale, Sensory Organisation Test, and Motor Control Test. Since partial post-treatment data were available for this patient, their missing values were replaced with the group mean. Additional missing data constituted less than 5% of the data, and were replaced with group means.
Overview of treatment outcomes
Figure 2. Results of mechanized measures for the real and sham treatment groups. A) Mean reaction time (RT), maximum velocity, and maximum extension on the Limit of Stability (LOS) test for forward and backward stepping, B) Mean composite scores and forward-backward Centre of Gravity (COG) alignment on the Sensory Organization Test (SOT), C) Mean composite latency scores on the Motor Control Test (MCT), D) Mean step length and step speed on the Walk Across (WA) test. Error bars represent ± 1SEM
Primary outcome measures: Change in postural control
Berg Balance Scale (Fig. 3). A Group (real, sham) x Time (pre, 1d post) ANOVA revealed no main effects or interactions (Fs ≤ 1.4, ps ≥ 0.25).
Mechanized Measures. We performed three Group (real, sham) x Time (pre, 1d post) x Stepping Direction (forward, backward) ANOVAs of reaction time, maximum velocity, and maximum extension on the Limits of Stability test (Fig. 2A). There was a main effect of Direction for maximum velocity (F(1, 27) = 17.7, p < .001, ηp2 = .367; Forward: M = 2.4, SEM = 0.16; Backward: M = 1.8, SEM = 0.12) and for maximum extension (F(1, 27) = 15.8, p < .001, ηp2 = .369; Forward: M = 68.2, SEM = 3.6; Backward: M = 56.9, SEM = 4.1), reflecting faster, and further, forward than backward stepping. There was also a Group x Time x Direction interaction for maximum velocity (F(1, 27) = 5.22, p = .03, ηp2 = 1.62). Follow-up t-tests revealed that the real treatment group showed increased maximum velocity for forward stepping following treatment (Pre: M = 2.33, SEM = 0.24; 1d post: M = 2.88, SEM = 0.26; t(15) = 3.2, p = .005, d = .819). There were no significant changes in forward stepping for the sham treatment group (Pre: M = 2.13, SEM = 0.22; 1d post: M = 2.24, SEM = 0.22; t(13) = .636, p = .537, d = .176), nor in backward stepping for either treatment group (ts < 1.68, ps > .118). There were no further main effects or interactions in the analyses for the Limits of Stability test (Fs ≤ 4.0, ps ≥ .056).
Group (real, sham) x Time (pre, 1d post) ANOVAs revealed no main effects or interaction in the analyses of the composite score (Fs ≤ 3.5, ps ≥ .074) and forward-backward displacement of COG (Fs ≤ 0.72, ps ≥ .40) from the Sensory Organization Test (Fig. 2B); nor for composite latency in the Motor Control Test (Fs ≤ .61, ps ≥ .441; Fig. 2C).
Secondary outcome measures: Change in gait
Group (real, sham) x Time (pre, 1d post) ANOVAs revealed no main effects or interactions (Fs ≤ 2.72, ps ≥ .11) for the Timed Up and Go test, the Functional Gait Assessment (Fig. 3), and mean step length and mean step speed in the Walk Across test (Fs ≤ .92, ps ≥ .35; Fig. 2D).
Self-Report Questionnaires
Group (real, sham) x Time (pre, 1d post, 1w post, 1 m post, 2 m post) ANOVAs were performed on the total scores of the New Freezing of Gait Questionnaire; Falls Efficacy Scale; Activities-specific Balance Confidence scale; and the mobility, activities of daily living, and total scores on the Parkinson’s Disease Questionnaire 39 (Fig. 4). There were no main effects or interactions for any analysis (Fs ≤ 2.27, ps ≥ .14)
Patient’s Global Impressions of Change ratings for overall function, walking, freezing, and balance were lower than 3 (“a little better”) across all time points and both groups, indicating little perceived change. A Group (real, sham) x Time (1d post, 1w post, 1 m post, 2 m post) x Measure (overall, freezing, walking, and balance) ANOVA was performed. There was a main effect of Group (F(1, 27) = 5.4, p = .028, ηp2 = .17): the real treatment group (M = 1.6, SEM = 0.19) perceived less change than the sham treatment group (M = 2.3, SEM = .22). None of the other main effects or interactions were significant (Fs ≤ 2.5, ps > .064).