Table 1
Demographic, neuropsychological, and physical performance data of the two training groups at T0.
| TRAINING GROUP | MODALITY COMPATIBLE (N=11) | MODALITY INCOMPATIBLE N = 10 | P-VALUE |
|---|---|---|---|
| Age (years) | 71.1 (±6.2) range = 65–83 yrs | 73.1 (±4.8) range = 66–79 yrs | .42 |
| Sex | female = 4 (36.3%) male = 7 (63.6%) | female = 6 (60%)male = 4 (40%) | .30 |
| Neuropsychology1 | |||
| Trail making test A (s) | 37.7 (8.6) | 46.1 (15.1) | .13 |
| Trail making test B (s) | 75.2 (22.5) | 109.0 (35.5) | .02 |
| CERAD immediate recall (# words) | 7.8 (1.0) | 8.0 (1.1) | .69 |
| CERAD delayed retrieval (# words) | 7.6 (2.0) | 8.00 (2.4) | .64 |
| DSST (# correct matches in 90s) | 49.3 (5.9) | 39.8 (9.0) | .01 |
| LPS subtest 3 (# correct symbols) | 20.6 (4.3) | 21.9 (5.5) | .54 |
| MWT (# correct words) | 32.7 (1.5) | 32.9 (2.1) | .83 |
| DST forward (# of digits) | 7.6 (1.7) | 8.6 (2.5) | .30 |
| DST backward (# of digits) | 6.2 (1.2) | 6.6 (2.3) | .60 |
| MMSE (points) | 28.9 (1.3) | 28.7 (1.1) | .69 |
| Physical Performance | |||
| 10 m walk test [DT(s)-ST(s)] | 12.6 (17.9) | 8.3 (10.0) | .51 |
| Timed Up and Go Test (s) | 6.6 (1.1) | 7.2 (1.3) | .31 |
| Hand grip strength test (kg) | 30.4 (9.7) | 32.2 (10.9) | .69 |
[i] 1 ANCOVAs with PCA factor scores representing neuropsychological status at baseline (see Table 4) as covariates did not reveal any significant effects for training group on the outcomes of the training intervention.
Figure 1a
Study design. After being recruited, participants were assigned to a compatible or incompatible training group. They were assessed for cognitive and postural performance and neuropsychological status at baseline (T0) and subsequently underwent a 6-week passive control period. After retesting (T1), they completed a 6- week multimodal balance training intervention and were tested a third time (T2).
Figure 1b
Task design. Variations of modality compatible and modality incompatible component one-back working memory tasks either performed as cognitive single task (C), cognitive-postural dual task (CP), cognitive-cognitive dual task (CC) or cognitive-cognitive-postural triple task (CCP) at T0, T1, and T2. Input stimuli were either visual or auditory with either manual or vocal (‘yes’) response output requirements. Visual displays consisted of 6 possible stimulus locations, 3 to the left and 3 to the right of the fixation cross presented for 500 ms, followed by a 1,500 ms inter-stimulus interval. Auditory input stimuli consisted of three different tones (200, 450, 900 Hz), presented via headphones to the left or to the right ear. Participants were asked to respond as fast and correct as possible to one-back targets via button press in the manual conditions or by saying “yes” in the vocal conditions. Depending on the part of the experiment, stimulus-response mappings were either modality compatible (i.e., visual-manual and auditory-vocal) or modality incompatible (i.e., visual-vocal and auditory-manual). One block lasted 33s and included 16 stimuli with five target stimuli.
Figure 1c
Design of test sessions (T0, T1, T2). Each test session included two parts (modality compatible, modality incompatible). Each part consisted of six runs (three in standing posture, three in sitting posture). Task blocks (33 secs) within each run were processed from left to right. Each run in standing posture included seven task blocks and each run in sitting posture three task blocks each. Each task block consisted of 16 trials (i.e. stimulus presentation). Explanations for Abbreviations are as follows: Pstable fix = postural single task with stable fixation, Pdynamic fix = postural single task with dynamic fixation; CPvm = cognitive-postural dual task with visual-manual stimulus-response pairing of cognitive task, CPav = cognitive-postural dual task with auditory-vocal stimulus-response pairing of cognitive task, CCPvm-av = cognitive-cognitive-postural triple task, CPvv = cognitive-postural dual task with visual-vocal stimulus-response pairing of cognitive task, CPam = cognitive-postural dual task with auditory-manual stimulus-response pairing, CCPvv-am = cognitive-cognitive-postural triple task. For further descriptions of tasks see Methods section.
Figure 2
Setup during a training session. Separated by visual barriers, participants (P1–P10) stood next to each other in the exercise room to perform the two main parts of the training session. Between main part 1 and main part 2, participants completed a circuit consisting of static and dynamic balance exercises in training area B using various equipment. Participants provided written consent for the publishing of the picture.
Table 2
Adaptive Training Paradigm.
| TRAINING LEVEL | COGNITIVE TASK | BALANCE TASK |
|---|---|---|
| L1 | 0-back Dual Task | bipedal parallel stance |
| L2 | 0-back Dual Task | bipedal parallel stance on balance pad |
| L3 | 1-back Dual Task | bipedal parallel stance on balance pad |
| L4 | 1-back Dual Task | semi-tandem stance |
| L5 | 1-back Dual Task | semi-tandem stance + balance pad |
| L6 | 2-back Dual Task | semi-tandem stance + balance pad |
| L7 | 2-back Dual Task | tandem stance |
| L8 | 2-back Dual Task | tandem stance + balance pad |
| L9 | 2-back Dual Task | one-legged-stance |
| L10 | 2-back Dual Task | one-legged-stance + balance pad |
Table 3
Significant main and interaction effects for cognitive and postural performance data.
| FACTOR/INTERACTION | F-VALUE | P | ηP2 |
|---|---|---|---|
| Main Analysis 3 (Time) × 2 (Training Group) ANOVA (CCP condition only) | |||
| Cognitive Performance | |||
| Time | F(1,19) = 16.70 | <.001 | .47 |
| Postural Performance | |||
| Time | F(1,19) = 3.79 | .031 | .17 |
| DTC (Costs) | |||
| Time | F(1,19) = 4.24 | .022 | .19 |
| Exploratory Follow-Up Analysis of Control Period (T0 vs. T1) (all task conditions) 2 (Time) × 2 (Modality Compatibility) × 2 (Task) × 2 (Posture) × 2 (Group) ANOVA | |||
| Cognitive Performance | |||
| Time | F(1,19) = 13.46 | .002 | .42 |
| Task (ST vs. DT) | F(1,19) = 72.05 | <.001 | .79 |
| Compatibility | F(1,19) = 7.96 | .011 | .30 |
| Posture | F(1,19) = 38.34 | <.001 | .67 |
| Time × Task | F(1,19) = 22.63 | <.001 | .54 |
| Compatibility × Task | F(1,19) = 17.28 | .001 | .476 |
| Posture x Task | F(1,19) = 32.77 | <.001 | .63 |
| DTC (Costs) | |||
| Time | F(1,19) = 22.51 | <.001 | .54 |
| Compatibility | F(1,19) = 15.33 | .001 | .45 |
| Reaction Times | |||
| Task | F(1,19) = 324.78 | <.001 | .95 |
| Task x Compatibility | F(1,19) = 12.73 | .003 | .44 |
| Postural Performance | |||
| Task | F(1,19) = 21.42 | <.001 | .53 |
| Exploratory Follow-Up Analysis of Training Period (T1 vs. T2) (all task conditions) 2 (Time) × 2 (Modality Compatibility) × 2 (Task) × 2 (Posture) × 2 (Training Group) ANOVA | |||
| Cognitive Performance | |||
| Task | F(1,19) = 65.41 | <.001 | .76 |
| Posture | F(1,19) = 17.18 | .001 | .48 |
| Posture × Task | F(1,19) = 7.35 | .014 | .28 |
| DTC (Costs) | |||
| Compatibility | F(1,19) = 17.23 | .001 | .48 |
| Reaction Times | |||
| Task | F(1,19) = 596.00 | <.001 | .97 |
| Task x Compatibility | F(1,19) = 14.53 | .001 | .46 |
| Postural Performance | |||
| Task | F(1,19) = 16.95 | <.001 | .47 |
Figure 3
Mean (±SE) postural performance data. Changes in center of pressure (CoP) displacements for the control and training period.
Figure 4
Individual trajectories of cognitive and postural performance in the cognitive-cognitive-postural triple task (CCP). Comparison of passive control period (retest effect) and training intervention (training effect).
Table 4
Summary of PCA results for the neuropsychological tests conducted at baseline.
| ITEM | ROTATED FACTOR LOADINGS | |||
|---|---|---|---|---|
| WORKING MEMORY | ATTENTIONAL CONTROL | PROCESSING SPEED | ||
| LPS (number of rows correctly identified) | .82 | –.08 | –.32 | |
| Trail Making Test A (time in s) | –.10 | .29 | .93 | |
| Trail Making Test B (time in s) | –.12 | .93 | .12 | |
| DSST (number of boxes filled in correctly in 90s) | .10 | –.89 | –.27 | |
| Digit Span A (score) | .91 | .01 | .10 | |
| Digit Span B (score) | .87 | –.24 | –.07 | |
| Eigenvalues | 2.20 | 1.43 | 1.14 | |
| % of variance | 36.98 | 23.78 | 19.06 | |
| α | .75 | .57 | .77 | |
Supplementary Figure
Mean (±SD) of cognitive performance (p(hit) – p(fa)) of both training groups for the different task types.
Supplementary Table
Correlation matrix for the PFA based on six neuropsychological items. (DTCc = dual-task costs in the postural domain; TTCp = triple-task costs in the postural domain).
| VARIABLE | WORKING MEMORY | ATTENTIONAL CONTROL | PROCESSING SPEED | |
|---|---|---|---|---|
| DTCc Gain compatible | r | .264 | –.146 | –.308 |
| p | .260 | .540 | .187 | |
| n | 20 | 20 | 20 | |
| DTCc Gain incompatible | r | .275 | .501* | .271 |
| p | .241 | .024 | .247 | |
| n | 20 | 20 | 20 | |
| TTCp Gain compatible | r | –.456* | .308 | .451* |
| p | .043 | .187 | .046 | |
| n | 20 | 20 | 20 | |
| TTCp Gain incompatible | r | –.286 | –.253 | .164 |
| p | .222 | .281 | .489 | |
| n | 20 | 20 | 20 | |
[i] * Significant at p ≤ .05.