Walking-Related Dual-Task Interference in Early-to-Middle-Stage Huntington's Disease: An Auditory Event Related Potential Study

Abstract

Objective: To compare interference between walking and a simple P3 auditory odd-ball paradigm in patients with Huntington's disease (HD) and age- and sex-matched controls. Methods: Twenty-four early-to-middle-stage HD patients and 14 age- and sex-matched healthy volunteers were examined. EEG-EMG recordings were obtained from 21 scalp electrodes and eight bipolar derivations from the legs. Principal component analysis was used to obtain artifact-free recordings. The stimulation paradigm consisted of 50 rare and 150 frequent stimuli and was performed in two conditions: standing and walking along a 10 by 5 m path. P3 wave amplitude and latency and EEG and EMG spectral values were compared by group and experimental condition and correlated with clinical features of HD. Results: P3 amplitude increased during walking in both HD patients and controls. This effect was inversely correlated with motor impairment in HD patients, who showed a beta-band power increase over the parieto-occipital regions in the walking condition during the P3 task. Walking speed and counting of rare stimuli were not compromised by concurrence of motor and cognitive demands. Conclusion: Our results showed that walking increased P3 amplitude in an auditory task, in both HD patients and controls. Concurrent cognitive and motor stimulation could be used for rehabilitative purposes as a means of enhancing activation of cortical compensatory reserves, counteracting potential negative interference and promoting the integration of neuronal circuits serving different functions.

Keywords: Huntington's disease; P3; acoustic paradigm; dual task; walking.

Figure 1

Grand average of the P3 wave by target (black line) and non-target (red line) stimuli in patients and controls, during standing and walking conditions.

Figure 2

Scalp maps of the P3 wave by rare and frequent stimuli are reported. The amplitude maps at the bottom of the figure represent the results of separate Student's t-tests for each group, where the color scale indicates the p-values. Significant results are shown in white and blue.

Figure 3

Means and 95% confidence intervals for P3 amplitude (on the right) and latency (on the left) to target stimuli, recorded over the Pz channels in HD patients and controls, during standing and walking conditions.

Figure 4

Means and 95% confidence intervals (CI) for the total spectral power of EMG activity, normalized by standing condition values and log-transformed, in the walking and walking+P3 conditions in HD patients and controls. Values from right anterior tibial (TIB-R-N-log) and left anterior tibial (TIB-L-N-log) muscles are reported. Results of separate paired-samples Student's t-tests for each group: ^**p < 0.01.

Figure 5

Means and 95% confidence intervals (CI) for total spectral power of EMG activity, normalized by standing condition values and log-transformed, in the walking and walking+P3 conditions in HD patients and controls. Values from right gastrocnemius (GSTR-R-N-log) and left gastrocnemius (GASTR-L-N-log) muscles are reported. Separate paired-samples Student's t-tests for the two groups were not significant.

Figure 6

Mean values and standard errors for alpha activity (top) and beta activity (bottom) in controls and HD patients. The results of separate Bonferroni tests for each group are reported, standing vs. walking and standing+P3 vs. walking+P3: ^*p < 0.05, ^**p < 0.01; standing vs. walking+P3 and standing+P3 vs. walking+P3: ⁺p < 0.05.

Figure 7

Linear dispersion graph for UHDRSM scores (Unified Huntington's Disease Rating Scale-Motor) and P3 amplitude over the Pz electrode in walking and standing conditions. A negative correlation was present in the walking condition (detailed statistical results are reported in Table 4).

Figure 8

Linear dispersion graph for bradykinesia and tandem walking (Unified Huntington's Disease Rating Scale-Motor items) and right gastrocnemius muscle recruitment (total spectral power of EMG activity, normalized by standing condition values and log-transformed) during walking and walking+P3. A negative correlation was present only in the walking condition (detailed statistical results are reported in Table S5).