Cognitive Dual Task Research Articles

Multiarea Brain Activation and Gait Deterioration During a Cognitive and Motor Dual Task in Individuals With Parkinson Disease.

In people with Parkinson disease (PD), gait performance deteriorating during dual-task walking has been noted in previous studies. However, the effects of different types of dual tasks on gait performance and brain activation are still unknown. The purpose of this study was to investigate cognitive and motor dual-task walking performance on multiarea brain activity in individuals with PD. Twenty-eight participants with PD were recruited and performed single walking (SW), walking while performing a cognitive task (WCT), and walking while performing a motor task (WMT) at their self-selected speed. Gait performance including walking speed, stride length, stride time, swing cycle, temporal and spatial variability, and dual-task cost (DTC) was recorded. Brain activation of the prefrontal cortex (PFC), premotor cortex (PMC), and supplementary motor areas (SMA) were measured using functional near-infrared spectroscopy during walking. Walking performance deteriorated upon performing a secondary task, especially the cognitive task. Also, a higher and more sustained activation in the PMC and SMA during WCT, as compared with the WMT and SW, in the late phase of walking was found. During WMT, however, the SMA and PMC did not show increased activation compared with during SW. Moreover, gait performance was negatively correlated with PMC and SMA activity during different walking tasks. Individuals with mild to moderate PD demonstrated gait deterioration during dual-task walking, especially during WCT. The SMA and PMC were further activated in individuals with PD when performing cognitive dual-task walking.Supplemental Digital Content is Available in the Text.Video Abstract available for more insights from the authors (see the Video, Supplemental Digital Content 1, available at: http://links.lww.com/JNPT/A383 ).

Cognitive dual-task alters Local Dynamic Stability of lower extremity during common movements

A dual-task paradigm is most commonly used in the field of biomechanics to understand the effect of multi-tasking or cognitive load on motor performance. The Local Dynamic Stability (LDS) is most commonly used to quantify motor performance, but there are still several unknown effects of this metric with varied task conditions and cognitive demands. Therefore, this study used motion capture to collect biomechanical data from 28 healthy collegiate participants during a walk and jog task both with and without a semantic fluency task to investigate the effects of task speed, limb dominance, and semantic fluency on LDS. This study showed that the change in ankle plantarflexion LDS during a jog was dependent on self-selected speed. Participants with slower jogging speeds increased ankle plantarflexion LDS during a dual-task, while individuals with faster jogging speeds decreased ankle plantarflexion LDS during a dual-task. This study also found that subjects compensate during gait by both increasing and decreasing LDS in different degrees of freedom of the lower extremity. This study did not find evidence of limb dominance effecting the change in LDS during a dual-task while walking or jogging. These findings reveal where healthy adults compensate for simple movement patterns while multitasking. Future work should further explore the role and relationship between trunk movement and lower extremity compensation, and could help give further context to how the LDS can be interpreted by researchers and clinicians alike.

A Novel Way of Measuring Dual-Task Interference: The Reliability and Construct Validity of the Dual-Task Effect Battery in Neurodegenerative Disease

Background. Decreased automaticity is common among individuals with neurodegenerative disease and is often assessed using dual-task (DT) paradigms. However, the best methods for assessing performance changes related to DT demands remain inconclusive. Objective. To investigate the reliability and validity of a novel battery of DT measures (DT Effect—Battery (DTE-B)) encompassing three domains: task-specific interference, task prioritization, and automaticity. Methods. Data for this retrospective cross-sectional study included 125 participants with Parkinson’s disease (PD), 127 participants with Alzheimer’s disease (AD), and 84 healthy older adults. Reliability analyses were conducted using a subset of each population. DTE-B measures were calculated from single and DT performance on the Timed Up and Go test and a serial subtraction task. Construct validity was evaluated via associations within the DTE-B and with theoretically supported measures as well as known-groups validity analyses. Results. Good to excellent reliability was found for DTE-B measures of task interference (motor and cognitive DT effects) (ICCs≥.658) and automaticity (combined DT effect (cDTE)) (ICCs≥.938). Evidence for convergent validity was found with associations within the hypothesized constructs. Known-groups validity analyses revealed differences in the DTE-B among the healthy group and PD and AD groups (ps≤.001), excepting task prioritization (ps≥.061). Conclusions. This study provides evidence to support the DTE-B as a reliable measure of multiple constructs pertinent to DT performance. The cDTE demonstrated evidence to support its validity as a measure of automaticity. Further investigation of the utility of the DTE-B in both PD and AD, as well as other populations, is warranted.

Comparing different montages of transcranial direct current stimulation on dual-task walking and cortical activity in chronic stroke: double-blinded randomized controlled trial

BackgroundTranscranial direct current stimulation (tDCS) is a noninvasive brain stimulation to modulate cortical activity for improving motor function. However, the different tDCS applications for modulating cortical activity and dual task gait performance in chronic stroke have not yet been investigated. This study investigated the effects of different tDCS applications on dual task gait performance and contralesional M1 activation in chronic stroke.MethodsForty-eight participants were randomized to anodal, bilateral, cathodal, and sham tDCS groups. Each group received 20 min of tDCS stimulation, except the sham group. Gait performance was measured by GaitRite system during cognitive dual task (CDT) walking, motor dual task (MDT) walking, and single walking (SW). Contralesional M1 activity of unaffected tibialis anterior (TA) was measured using transcranial magnetic stimulation (TMS). Intragroup difference was analyzed by Wilconxon sign ranks test with Bonferroni correction, and Kruskal–Wallis one-way analysis of variance by ranks was used for intergroup comparisons, followed by post-hoc Mann–Whitney U tests with Bonferroni correction.ResultsThe bilateral tDCS (p = 0.017) and cathodal tDCS (p = 0.010) improved the CDT walking speed more than sham group. The bilateral tDCS (p = 0.048) and cathodal tDCS (p = 0.048) also improved the MDT walking speed more than sham group. Furthermore, bilateral tDCS (p = 0.012) and cathodal tDCS (p = 0.040) increased the silent period (SP) more than the anodal and sham group. Thus, one-session of bilateral and cathodal tDCS improved dual task walking performance paralleled with increasing contralesional corticomotor inhibition in chronic stroke.ConclusionsOur results indicate that one-session of bilateral and cathodal tDCS increased contralesional corticomotor inhibition and improved dual task gait performance in chronic stroke.Trial registrationThai Clinical Trials Registry (TCTR20180116001). Registered prospectively on 16th Jan, 2018 at http://www.thaiclinicaltrials.org.

"Prefrontal Cortex Neuromodulation Improves Motor-Cognitive Components in Latinx Hispanic People Living with HIV"

Background: HIV is an immunodeficiency virus that currently has no cure but is managed with antiretroviral medication (ART). ART has increased the life expectancy of those living with HIV. Evidence shows a correlation between the increase in life expectancy and increases in neurological motor-cognitive impairments, thus leading to a decline in functional mobility and overall quality of life. The current study aimed to address neurological motor cognitive impairments in Latinx HIV+ individuals using transcranial direct current stimulation (tDCS).Methods: Female and male participants, ages 18-65, with an HIV diagnosis by a medical doctor and a CD4 count of >300 were obtained from an HIV clinic in La Perla de Gran Precio in Puerto Rico. Spatiotemporal data were collected; each subject participated in a dual cognitive ambulation task and completed the HIV dementia scale.Results: Dual cognitive tasks were calculated for cadence, gait cycle, gait speed, single limb, double limb, stance, stride, swing, and sway were analyzed. After the application of tDCS, the only statistically significant difference found among the subjects was an improvement in gait speed (p≤.05). In addition, the cognitive component showed an improvement in the HIV dementia scale total (p≤.05), including an increase in motor speed and memory recall (p≤.05).Conclusion: tDCS may be a feasible and effective treatment option for this population to alleviate motor-cognitive alterations in those living with HIV. Future research should consider the benefits of tDCS combined with diverse training, such as gait or balance activities.

Cognitive Dual Tasking Impacts Lower Limbs Inter-Segmental Coordination During Walking in Patients with Multiple Sclerosis

Background: Gait disturbance is one of the most common and disabling signs in patients with multiple sclerosis (MS). Coordinative ability between segments of lower extremities, as a higher order property of the human movement system, is affected by MS disease. Since intersegmental coordination could be affected by cognitive loading, this study was aimed to investigate the interaction between cognition and lower extremities inter-segmental coordination during walking in patients with MS.

Does dual task merged in a mixed physical exercise protocol impact the mobility under dual task conditions in mild impaired stroke survivors? A feasibility, safety, randomized, and controlled pilot trial

Purpose To investigate the feasibility, safety, and effects of dual task (DT) in a mixed physical exercise protocol on mobility under DT in stroke survivors. Materials and methods Twenty-six chronic mild-impaired stroke survivors (age 51.57 ± 12.55; men= 13, women= 13) were randomly assigned into Experimental Group participating in a 15-week mixed (aerobic and resistance exercises performing a cognitive DT condition simultaneously) physical exercise protocol (30 sessions, 2x/week, duration of 60–90 min), and Control Group engaged in the same protocol without DT. Feasibility and outcome measures were assessed before and after the intervention and in a 5-week follow-up. Results DT physical exercise protocol was viable and safe. This protocol also improved mobility and gait when performed under DT, which was not found in the control group. DT does not influence aerobic resistance, strength, and balance responsiveness. It does not present any improvement in cognition, self-efficacy for falls, and quality of life. Conclusion The results indicate that mixed physical exercise under DT is feasible and safe for mild-impaired stroke survivors. Stroke survivors demonstrate more significant improvement in the mobility performance under DT when submitted to a DT mixed physical exercise protocol than the standard physical exercise intervention. Trial registration Brazilian clinical trials registry (RBR-4mvzz6); WHO trial record (U1111-1198-7173) IMPLICATIONS FOR REHABILITATION DT training can be prescribed by using clear and precise parameters for stroke survivors. Physical Exercise without DT requirements did not improve mobility performing and cognitive tasks simultaneously in stroke survivors. Clinicians are encouraged to incorporate DT requirements into the exercise routines to enhance mobility under DT to mild-moderate stroke survivors.

The Impact of Visual and Cognitive Dual-Task Demands on Traffic Perception During Road Crossing of Older and Younger Pedestrians.

With the help of the current experiment, we wanted to learn more about the impact of visually demanding vs. cognitively demanding secondary tasks on the attention allocation of older pedestrians during the phase of traffic perception within the process of road crossing. For this purpose, we used two different road crossing tasks as well as two different secondary tasks. The road crossing “stop task” was a signal detection task, where an approaching car had to be detected. The road crossing “go task” was a dynamic visual search task, where the resolution of a busy road situation had to be identified. The visual secondary task was a static visual search task and the cognitive secondary task was a 1-back (memory) task. One younger group (≤ 30 years) and one older group (≥ 65 years) of participants completed the tasks as single vs. dual-tasks in all possible combinations. Performance was measured through errors and response time; in addition, the subjective workload was assessed via NASA-TLX. Analyses show that the visual secondary task reduces performance in the road crossing more strongly than the cognitive task, while the visual task itself is less impaired by the road crossing tasks than is the cognitive task. Overall, performance diminishes from single to dual-task completion. Results further indicate age effects in terms of increased errors and response time for older compared to younger participants. In addition to these age effects, age-specific dual-task effects emerge for response time in the go task along with the visual task as well as for response time in the cognitive task along with the go task. Subjective workload is higher in the dual-task conditions than in the single tasks. Findings are discussed with regard to theoretical and practical implications.

Patients Surviving Critical COVID-19 have Impairments in Dual-task Performance Related to Post-intensive Care Syndrome.

ObjectiveThe purpose was to examine Dual Task (DT) performance in patients surviving severe and critical COVID-19 compared to patients with chronic lung disease (CLD). Secondarily, we aimed to determine the psychometric properties of the Timed Up and Go (TUG) test in patients surviving COVID-19.DesignProspective, cross-sectional, observational study.SettingAcademic medical center within United States.PatientsNinety-two patients including 36 survivors of critical COVID-19 that required mechanical ventilation (critical-COVID), 20 patients recovering from COVID-19 that required supplemental oxygen with hospitalization (severe-COVID), and 36 patients with CLD serving as a control group.Measurements and Main ResultsPatients completed the TUG, DT-TUG, Short Physical Performance Battery (SPPB), and Six Minute Walk Test (6MWT) 1-month after hospital discharge. A subset of patients returned at 3-months and repeated testing to determine the minimal detectable change (MDC). Critical-COVID group (16.8 ± 7.3) performed the DT-TUG in significantly slower than CLD group (13.9 ± 4.8 s; P = .024) and Severe-COVID group (13.1 ± 5.1 s; P = .025). Within-subject difference between TUG and DT-TUG was also significantly worse in critical-COVID group (−21%) compared to CLD (−10%; P = .012), even despite CLD patients having a higher comorbid burden (P < .003) and older age (P < .001). TUG and DT-TUG demonstrated strong to excellent construct validity to the chair rise test, gait speed, and 6MWT for both COVID-19 groups (r = −0.84to 0.73, P < .05). One- and 3-months after hospital discharge there was a floor effect of 14% (n = 5/36) and 5.2% (n = 1/19), respectively for patients in the critical-COVID group. Ceiling effects were noted in four (11%) critical-COVID, six (30%) severe-COVID patients for the TUG and DT-TUG at 1-month.ConclusionThe ability to maintain mobility performance in the presence of a cognitive DT is grossly impaired in patients surviving critical COVID-19. DT performance may subserve the understanding of impairments related to Post-intensive care syndrome (PICS) for survivors of critical illness.

Effect of cognitive task complexity on dual task postural stability: a systematic review and meta-analysis.

The dual task experimental paradigm is used to probe the attentional requirements of postural control. However, findings of dual task postural studies have been inconsistent with many studies even reporting improvement in postural stability during dual tasking and thus raising questions about cognitive involvement in postural control. A U-shaped non-linear relationship has been hypothesized between cognitive task complexity and dual task postural stability suggesting that the inconsistent results might have arisen from the use of cognitive tasks of varying complexities. To systematically review experimental studies that compared the effect of simple and complex cognitive tasks on postural stability during dual tasking, we searched seven electronic databases for relevant studies published between 1980 to September 2020. 33 studies involving a total of 1068 participants met the review's inclusion criteria, 17 of which were included in meta-analysis (healthy young adults: 15 studies, 281 participants; Stroke patients: 2 studies, 52 participants). Narrative synthesis of the findings in studies involving healthy old adults was carried out. Our result suggests that in healthy population, cognitive task complexity may not determine whether postural stability increases or decreases during dual tasking (effect of cognitive task complexity was not statistically significant; P > 0.1), and thus the U-shaped non-linear hypothesis is not supported. Rather, differential effect of dual tasking on postural stability was observed mainly based on the age of the participants and postural task challenge, implying that the involvement of cognitive resources or higher cortical functions in the control of postural stability may largely depends on these two factors.

Moderate Intensity Cycling Combined with Cognitive Dual-task Improves Selective Attention.

Physical and cognitive exercises have positive long-term effects on cognitive capacities. However, acute effects still are controversial. Here we determine the acute effects of physical exercise combined with concurrent cognitive exercise on cognitive performance in young adults. Simple reaction time, selective attention, and memory were evaluated in 23 young men before and after 30 min of stationary cycling exercise, 30 min of stationary cycling exercise combined with cognitive exercise, and 30 min of rest. Exercise intensity was continuously controlled to ensure exercise at moderate intensity. We found that physical exercise combined with cognitive dual-task improves selective attention. Both exercise conditions showed similar effects on simple reaction time, and memory was not affected by the different exercise conditions. We conclude that the combination of cycling exercise at moderate intensity with a cognitive exercise acutely improves selective attention in young adults. These results can be of particular interest for interventions aiming at improving selective attention in sports and for older adults and individuals with difficulty to suppress and filter out task-irrelevant information, like when receiving instruction or learning a new task or concept.

Motor-Cognitive Treadmill Training With Virtual Reality in Parkinson's Disease: The Effect of Training Duration.

Treadmill training with virtual reality (TT + VR) has been shown to improve gait performance and to reduce fall risk in Parkinson’s disease (PD). However, there is no consensus on the optimal training duration. This study is a sub-study of the V-TIME randomized clinical trial (NCT01732653). In this study, we explored the effect of the duration of training based on the motor–cognitive interaction on motor and cognitive performance and on fall risk in subjects with PD. Patients in Hoehn and Yahr stages II–III, aged between 40 and 70 years, were included. In total, 96 patients with PD were assigned to 6 or 12 weeks of TT + VR intervention, and 77 patients completed the full protocol. Outcome measures for gait and cognitive performance were assessed at baseline, immediately after training, and at 1- and 6-month follow-up. The incident rate of falls in the 6-month pre-intervention was compared with that in the 6-month post-intervention. Dual-task gait performance (gait speed, gait speed variability and stride length under cognitive dual task and obstacle negotiation, and the leading foot clearance in obstacle negotiation) improved similarly in both groups with gains sustained at 6-month follow-up. A higher decrease in fall rate and fear of falling were observed in participants assigned to the 12-week intervention than the 6-week intervention. Improvements in cognitive functions (i.e., executive functions, visuospatial ability, and attention) were seen only in participants enrolled in 12-week training up to 1-month follow-up but vanished at the 6-month evaluation. Our results suggest that a longer TT + VR training leads to greater improvements in cognitive functions especially those directly addressed by the virtual environment.

The Effects of Neuromuscular Training with Dual Cognitive Tasks on Some Kinematic Indicators of Landing in Futsal Players with Knee Ligament Dominance Defect: A Clinical Trial Study

The Effects of Neuromuscular Training with Dual Cognitive Tasks on Some Kinematic Indicators of Landing in Futsal Players with Knee Ligament Dominance Defect: A Clinical Trial Study

Motor Control Alterations and the Perception of Postural Instability in non-Fallers Latinx-Hispanic Adults Living with HIV

People who have advanced HIV can display inadequate postural control because of the virus affecting the brain. Antiretroviral therapy (ART) mitigates some repercussions of the disease, maintaining a healthy immune system. The issue is that prolonged usage of ART may affect balance at a slower pace. Purpose: Assess postural control and balance perception in Latinx-Hispanic people living with HIV with a stable immune system. Methods: 42 (30 men and 12women) subjects took part in the investigation (57.2± 8.7 years old). Participants had to be diagnosed with HIV to enroll in the study with a CD4 count of &gt; 500 cells/µL. The eight balance tasks (15 s each) were accomplished on a thick balance foam mat and further partitioned into two parts, four single and four dual cognitive tasks (subjects counting backward three numbers at a time). Results: We measured balance using body-worn accelerometers (ACC) and the ABC scale. There was a considerable increase in sway movements within the different tasks, χ2 (8) = 194.314, p = 0.00. This increment in postural movements was observed when single and dual tasks were contrasted for EO (Z=-2.169, p=005) and EOHUD (Z=-2.344, p 0.05). Related to the ABC scale, subjects scored lower, notably in tasks involving more balance demands. Conclusion: HIV-diagnosed individuals with a stable immune system exhibit increased postural alteration and perceive balance difficulties with activities requiring higher motor control demands. Clinicians should assess the balance in people living with HIV in all stages of the disease as a prevention tool.

Dual Task Performance Is Associated with Amyloidosis in Cognitively Healthy Adults.

Preclinical Alzheimer's disease (AD) provides an opportunity for the study and implementation of interventions and strategies aimed at delaying, mitigating, and preventing AD. While this preclinical state is an ideal target, it is difficult to identify efficiently and cost-effectively. Recent findings have suggested that cognitive-motor dual task paradigms may provide additional inference. Investigate the relationship between dual task performance and amyloidosis, suggestive of preclinical Alzheimer's disease and whether dual task performance provides additional information beyond a cognitive composite, to help in the identification of amyloidosis. Cross-sectional. Outpatient specialty brain health clinical research institution in the United States. 52 cognitively healthy adults. The data included demographics, amyloid standardized uptake value ratio obtained via florbetapir-PET, neuropsychological testing, apolipoprotien E genotype, and dual task performance measures. Data were analyzed via hierarchal multiple linear regression or logistic regression, controlling for age, education, and apolipoprotien E genotype. Receiver operating characteristic curves were plotted, and sensitivity and specificity calculated via 2x2 contingency tables. There was a moderate relationship (rs>.30) between motor and cognitive dual task effects and amyloid standardized uptake value ratio (ps<.042). A strong relationship (r=.58) was found between combined dual task effect, a measure of automaticity derived from dual task performance, and amyloid standardized uptake value ratio (p<.001). Additionally, combined dual task effect showed promise in its unique contributions to amyloid standardized uptake value ratio, accounting for 7.8% of amyloid standardized uptake value ratio variance beyond cognitive composite scores (p=.018). Additionally, when incorporated into the cognitive composite, combined dual task effect resulted in improved diagnostic accuracy for determining elevated amyloid standardized uptake value ratio, and increased the sensitivity and specificity of the cognitive composite. Dual task performance using the combined dual task effect, a measure of automaticity, was a moderate predictor of cerebral amyloidosis, which suggests that it has utility in the screening and diagnosis of individuals for preclinical AD. Additionally, when combined with the cognitive composite, the combined dual task effect improves diagnostic accuracy. Further research is warranted.

Cognitive and physical benefits of a game-like dual-task exercise among the oldest nursing home residents in Japan.

IntroductionDual‐task (DT) exercise can act as a substitute, which can help improve both physical and cognitive functions. Thus, this study investigated the effects of a game‐like cognitive DT exercise called “Synapsology” (SYNAP) among the oldest residents of a nursing home.MethodsParticipants (aged 85–97 years) were assigned to the intervention group (n = 12) and the control group (n = 12). The intervention group underwent 60‐minute sessions, twice a week for 24 weeks.ResultsA comparison of the Mini‐Mental State Examination scores and six physical function tests, before and after the intervention, shows that the SYNAP had a positive impact on the cognitive and physical functions among the intervention group.DiscussionThese findings suggest that SYNAP may help maintain or improve cognitive and physical functions among older adults compared to no interventions. Therefore, SYNAP would act as a beneficial tool amidst a “superaging” society like Japan.

The Effect of Cognitive Task on Postural Control Dynamic Regularity of Athletes With Chronic Ankle Instability When Standing on an Unstable Surface

Background and Objectives: Postural control disorder is a common complication in patients with Chronic Ankle Instability (CAI). The present study aimed to investigate the effect of dual cognitive task on postural control behavior with regard to the Center of Pressure (CoP) signal regularity while standing on an unstable surface in athletes with CAI. Methods: In the present study, 58 men participated in two groups of healthy and patients with CAI. The CoP signal was examined in 4 different unstable states on the wobble board located at the center of the force plate. The regularity of the signals recorded from the force plate was investigated using sample entropy in two directions: anterior-posterior and medial-lateral. Results: In both groups, there was a significant difference in CoP’s sample entropy signal when performing a cognitive task with a postural task (P&lt;0.001). There was a significant difference between the two groups in the cognitive task and the single task in the anteroposterior direction while standing on two legs. Conclusion: During dual tasks, the patients with CAI have a more dynamic regularity in the CoP signal than their normal counterparts. In the dual-task condition, more irregularities are observed in the CoP signal of healthy individuals. In unstable conditions, patients with CAI decrease the adaptability of postural control behavior with increasing CoP signal regularity.

Effects of Task Demands on Postural Control in Children of Different Ages: A Cross-Sectional Study

This study evaluates the effect of dual tasks on balance during manipulation of visual information, the base of support, and cognitive tasks in 7–12-year-old children and adults. An equal number of girls (210) and boys (210) were selected from the schools by the cluster random sampling method (within the 7–12 age groups). Twenty young adults were also selected. Postural sway (PS) was measured in the anterior–posterior (AP) and mediolateral (ML) directions using a force plate in eight standing positions, including standing with closed eyes versus standing with open eyes and standing with feet together versus on a single limb, under the interference of cognitive dual tasks (DT) or a single task (ST). PS was found to decrease with advancing age. PS was also greater in men than women in both AP and ML directions (p &lt; 0.05). PS was greater in the 7–12-year-old participants compared to adults under the manipulation of the base of support (p &lt; 0.05). However, PS increased in all participants regardless of their age while manipulating both the base of support and visual information (p &lt; 0.05). Children (within the 9–12 years age range) and adults could keep their balance while performing basic tasks; however, children had difficulty in maintaining their balance with higher task demands.

The Effect of a Verbal Cognitive Task on Postural Sway Does Not Persist When the Task Is Over.

Dual-task balance studies explore interference between balance and cognitive tasks. This study is a descriptive analysis of accelerometry balance metrics to determine if a verbal cognitive task influences postural control after the task ends. Fifty-two healthy older adults (75 ± 6 years old, 30 female) performed standing balance and cognitive dual-tasks. An accelerometer recorded movement from before, during, and after the task (reciting every other letter of the alphabet). Thirty-six balance metrics were calculated for each task condition. The effect of the cognitive task on postural control was determined by a generalized linear model. Twelve variables, including anterior–posterior centroid frequency, peak frequency and entropy rate, medial-later entropy rate and wavelet entropy, and bandwidth in all directions, exhibited significant differences between baseline and cognitive task periods, but not between baseline and post-task periods. These results indicate that the verbal cognitive task did alter balance, but did not bring about persistent effects after the task had ended. Traditional balance measurements, i.e., root mean square and normalized path length, notably lacked significance, highlighting the potential to use other accelerometer metrics for the early detection of balance problems. These novel insights into the temporal dynamics of dual-task balance support current dual-task paradigms to reduce fall risk in older adults.

Combining Transcranial Direct Current Stimulation With Tai Chi to Improve Dual-Task Gait Performance in Older Adults With Mild Cognitive Impairment: A Randomized Controlled Trial.

Introduction: Engaging in a secondary task while walking increases motor-cognitive interference and exacerbates fall risk in older adults with mild cognitive impairment (MCI). Previous studies have demonstrated that Tai Chi (TC) may improve cognitive function and dual-task gait performance. Intriguingly, with emerging studies also indicating the potential of transcranial direct current stimulation (tDCS) in enhancing such motor-cognitive performance, whether combining tDCS with TC might be superior to TC alone is still unclear. The purpose of this study was to investigate the effects of combining tDCS with TC on dual-task gait in patients with MCI.Materials and Methods: Twenty patients with MCI were randomly assigned to receive either anodal or sham tDCS, both combined with TC, for 36 sessions over 12 weeks. Subjects received 40 min of TC training in each session. During the first 20 min, they simultaneously received either anodal or sham tDCS over the left dorsolateral prefrontal cortex. Outcome measures included dual-task gait performance and other cognitive functions.Results: There were significant interaction effects between groups on the cognitive dual task walking. Compared to sham, the anodal tDCS group demonstrated a greater improvement on cadence and dual task cost of speed.Conclusion: Combining tDCS with TC may offer additional benefits over TC alone in enhancing dual-task gait performance in patients with MCI.Clinical Trial Registration: [www.ClinicalTrials.gov], identifier [TCTR20201201007].