Dual-task Costs Research Articles

Multitasking practice eliminates modality-based interference by separating task representations in sensory brain regions.

The debate on the neural basis of multitasking costs evolves around neural overlap between concurrently performed tasks. Recent evidence suggests that training-related reductions in representational overlap in fronto-parietal brain regions predict multitasking improvements. Cognitive theories assume that overlap of task representations may lead to unintended information exchange between tasks (i.e., crosstalk). Modality-based crosstalk was suggested as a source for multitasking costs in multisensory settings. Robust findings of increased costs for certain modality mappings may be explained by crosstalk between the stimulus modality in one task and sensory action consequences in the concurrently performed task. Whether modality-based crosstalk emerges from representational overlap in general fronto-parietal multitasking regions or modality-specific regions is not known yet. In this functional neuroimaging study, we investigate neural overlap during multitasking performance in humans, focusing on modality compatibility by employing multivariate pattern analysis and modality-specific practice interventions in three groups (total N = 54, 24 females). We observed significant differences between modality compatible and modality incompatible single-task representations, specifically in the auditory cortex but not in fronto-parietal regions. Notably, improved auditory decoding accuracy related to modality incompatible tasks was predictive of performance gains in the corresponding dual task along with complete elimination of modality-specific dual-task costs. This predictive relationship was evident only in the group practicing modality incompatible mappings, suggesting that specific practice on task sets with modality overlap influenced both neural representations and subsequent multitasking performance. This study contributes to the integration of cognitive theory and neuroscience and the role of task representations in dual-task interference.Significance Statement In a society dominated by multitasking, understanding its neurocognitive basis and plasticity is crucial for key aspects of everyday tasks. We investigate the neural mechanisms behind multitasking limitations, offering insights for targeted cognitive interventions. The study builds upon established theories of cognitive multitasking and imaging research, addressing the concept of modality-based crosstalk - the unintended exchange of modality-based information between tasks. Through functional brain imaging and pattern analysis, we examined how neural task representations contribute to performance costs in dual tasks with varying degrees of modality overlap. Notably, our findings demonstrate a practice-related decrease in neural overlap which is associated with substantial multitasking improvements, specifically in the auditory cortex, emphasizing the contribution of sensory regions to flexible multidimensional task representations.

Distinct Neural Mechanisms Underlying Dual-Task Priority During Gait Across Cognitive and Motor Networks.

Background: Prioritization strategy during gait significantly influences gait performance and successful gait relies on interactions between cognitive and motor functions. This study aimed to examine the within- and between-network connectivities of cognitive and motor networks associated with dual-task priority during gait. Methods: Twenty-nine healthy individuals (66.86 ± 8.53 years) underwent the timed-up-and-go (TUG) test alone, TUG with a cognitive task, and the cognitive task alone. The cognitive task involved sequentially subtracting three from a random number between 50 and 100. The resting-state functional magnetic resonance imaging was acquired on the same day. Using independent component analysis, the dorsal attention network (DAN), frontoparietal network (FPN), primary motor network (PM), and lateral motor network were assessed. The participants were divided into cognitive and motor priority groups based on the modified attention allocation index (mAAI). Group comparisons of within- and between-network connectivity were conducted using permutation tests. Additionally, correlation analysis was employed to investigate the association between-network connectivity and task priority. Results: The cognitive priority group showed cognitive dual-task facilitation. In comparison to the motor priority group, they also showed comparable motor dual-task costs and lower combined dual-task costs. They exhibited increased within-network connectivity in the left FPN and enhanced between-network connectivity between the right FPN and both the DAN and PM. These between-network connectivities were negatively correlated with mAAI scores. Conclusion: The results suggest distinct neural mechanisms across cognitive and motor networks based on individuals' dual-task strategies. This may have implications for understanding gait performance in complex contexts.

Exploring the essence of a creative dance programme for older adults: Programme overview and research insights

IntroductionDance is recognised as a safe, effective, and enjoyable means to boost physical, mental, and cognitive health in older adults. Detailed content of dance programmes for this age group is sparsely described. AimsThis study provides a comprehensive description and evaluation of a Creative Dance Programme for older adults. MethodThe dance programme, described in detail in our study, was analysed with three quantitative (i.e., gait, balance and executive function tests) and one qualitative (i.e., interviews) pilot studies to gain insights into health effects of the programme. ResultsCreative dance increased participants walking speed in both the single (t(13) = 6.65, p < 0.001) and dual-task conditions (t(13) = 5.51, p < 0.001) and reduced participants’ dual-task costs of walking (t(13) = -2.24, p = 0.043). Moreover, participants reported that they felt energised after the sessions and more confident in daily activities. ConclusionOur research highlights that creative dance programmes can have a positive effect on the dual task costs of walking and movement adaptability in daily life of older adults.

Factors Influencing Gait Performance: Comfortable Linear Gait and Complex Gait in School-Aged Children in a Dual-Task Model

The aim of this study was to determine the effect of cognitive interference by using the Dual-Task (DT) paradigm on gait parameters according to sex, and age. Additionally, we aim to explore the relationship between Dual-Task-Cost (DTC), physical fitness, cognitive functioning, and weight status in schoolchildren. One hundred schoolchildren participated in this study (age = 8.83 ± 1.82 years). They were randomly assigned to Comfortable Linear Gait (CLG: gait in a straight path) or Complex Gait (CG: gait over obstacles) with and without interference. For CLG, boys and girls showed a reduction in gait speed (p < 0.001), cadence (p < 0.01), and step length (p < 0.001). In addition, double support time (p < 0.05) and cadence coefficient of variance (boys= p < 0.01; girls= p < 0.05) increased in the DT condition. In the CG, both sexes (p < 0.001) exhibited a worse execution time. There were significant effects on speed DTC between 8-9 vs. 10-11 years in CLG and 6-7 vs. 10–11 years in CGT (p < 0.05). In conclusion, gait parameters during CLG and CG are modified in the DT condition, resulting in a slower gait with shorter steps, regardless of age and sex. DTC is associated with physical fitness and cognitive function.

ERP neural correlates of the interpreter advantage in coordination for interpreting students

Abstract The task of interpreting requires managing multiple tasks simultaneously, but how this practice of multitasking may contribute to the nonverbal domain of executive functioning has been explored in only a few studies, and little is known about the Event-related Potentials (ERP) neural correlates of this potential advantage. To fill this gap, we conducted an ERP study asking consecutive interpreting students and bilingual controls to perform a psychological refractory period (PRP) dual-task, comprising an auditory (Task 1) and a visual (Task 2) discrimination task. They were performed separately or together, the performance differences between which, i.e., dual-task costs, served as indices of coordination. Smaller costs for interpreting students in either or both tasks are considered an interpreter advantage in coordination, and those confined to Task 2 further indicate an advantage in bottleneck switching. The latter was exactly observed in stimulus-locked lateralized readiness potential (LRP) onset latency, suggesting such an advantage was probably due to efficient switching from the response selection of one task to that of the other at the bottleneck stage of dual-task processing. Smaller dual-task costs of stimulus-locked LRP onset latency thus constitute the neural correlates of the interpreter advantage in coordination.

Cognitive functions explain discrete parameters of normal walking and dual-task walking, but not postural sway in quiet stance among physically active older people.

Postural control is dependent on the central nervous system's accurate interpretation of sensory information to formulate and execute adequate motor actions. Research has shown that cognitive functions are associated with both postural control and fall risk, but specific associations are not established. The aim of this study was to explore how specific components of everyday postural control tasks are associated with both general and specific cognitive functions. Forty-six community-dwelling older adults reported their age, sex, physical activity level, falls and fall-related concerns. The following cognitive aspects were assessed: global cognition, executive functions, processing speed and intraindividual variability. Postural control was quantified by measuring postural sway in quiet stance, walking at a self-selected pace, and walking while performing a concurrent arithmetical task. Separate orthogonal projections of latent structures models were generated for each postural control outcome using descriptive and cognitive variables as explanatory variables. Longer step length and faster gait speed were related to faster processing speed and less intraindividual variability in the choice reaction test. Moreover, longer step length was also related to less fall-related concerns and less severe fall-related injuries, while faster gait speed was also related to female sex and poorer global cognition. Lower dual-task cost for gait speed was explained by the executive function inhibition and faster processing speed. Postural sway in quiet stance was not explained by cognitive functions. Cognitive functions explained gait speed and step length during normal walking, as well as the decrease of gait speed while performing a concurrent cognitive task. The results suggest that different cognitive processes are important for different postural control aspects. Postural sway in quiet stance, step time and gait variability seem to depend more on physical and automatic processes rather than higher cognitive functions among physically active older people. The relationships between cognitive functions and postural control likely vary depending on the specific tasks and the characteristics of different populations.

Obstacle negotiation while dual-tasking in children with Developmental Coordination Disorder (DCD): An augmented-reality approach

BackgroundChildren with Developmental Coordination Disorder (DCD) exhibit deficits in predictive motor control, balance, and aspects of cognitive control, which are important for safely negotiating obstacles while walking. As concurrent performance of cognitive and motor tasks (dual-tasking) may exacerbate these deficits, we examined motor and cognitive dual-tasking differences between children with DCD and their typically developing (TD) peers during obstacle negotiation. Methods34 children aged 6–12 years (16 TD, 18 DCD) walked along a 12 m path, stepping over an obstacle (30 % or 50 % of leg length) at its mid-point. On dual-task trials, participants completed a simple or complex (cognitive) visual discrimination task presented via an augmented reality headset. Proportional dual-task costs (pDTCs) were measured on cognitive and gait outcomes over three phases: pre-obstacle, obstacle step-over, and post-obstacle. ResultsDuring the obstacle step-over phase, both groups increased their leading leg clearance when dual-tasking, while the DCD group had larger pDTC than TD for the high obstacle under simple stimulus conditions (viz simple-high combination). The complex cognitive task produced larger pDTCs than the simple one on leading leg clearance and post-obstacle gait variability. ConclusionsIn general, both DCD and TD groups showed similar pDTCs under complex conditions, while the specific deficit in DCD under the simple-high combination suggests a (default) compensatory strategy during step-over when attention is diverted to a secondary task. Competing cognitive and motor demands during obstacle negotiation present a potential safety risk for children.

Effect of task difficulty on dual-task cost during dual-task walking in people with multiple sclerosis

BackgroundCognitive-motor dual-task walking results a decrease in walking performance of patients with multiple sclerosis (PwMS) and it is known as dual-task cost (DTC). However, there is a lack of evidence about the effects of dual-tasks with hierarchical difficulty on DTC in PwMS. Research questionThis study aimed to investigate the effect of task difficulty on DTC during cognitive-motor dual-task walking in people with multiple sclerosis (PwMS). Methods32 PwMS and 32 healthy controls were included. The 6-meter walking test (6-Meter WT) with comfortable speed was used as single-task walking condition. For dual-task conditions, walking tasks and cognitive tasks at two difficulty levels (simple and difficult) were combined and DTC for four cognitive-motor dual-task walking conditions as simple motor-simple cognitive (SM-SC), simple motor-difficult cognitive (SM-DC), difficult motor-simple cognitive (DM-SC) and difficult motor-difficult cognitive (DM-DC) were calculated. The 6-Meter WT was used also for simple dual-task walking task. The 6-Meter WT was applied by walking in a narrow base condition for creating a difficult dual-task walking task. For cognitive task difficulty, participants were asked to count backwards by 3 as simple cognitive task and by 7 as difficult cognitive task. ResultsDTC was higher in PwMS than control subjects. DTC in all conditions were different (SM-SC<SM-DC<DM-SC<DM-DC). DTC was higher in PwMS than control subjects in three conditions and was similar SM-SC condition. In addition, DTC in all conditions (SM-SC<SM-DC<DM-SC<DM-DC) were different in both PwMS and control subjects. ConclusionThe results suggest that task difficulty affects the magnitude of DTC during cognitive-motor dual-task walking in PwMS. Moreover, difficult walking tasks combined with simple cognitive tasks result greater DCT on walking than simple walking tasks combined with difficult cognitive tasks.

The inertial-based gait normalcy index of dual task cost during turning quantifies gait automaticity improvement in early-stage Parkinson’s rehabilitation

BackgroundThe loss of gait automaticity is a key cause of motor deficits in Parkinson’s disease (PD) patients, even at the early stage of the disease. Action observation training (AOT) shows promise in enhancing gait automaticity. However, effective assessment methods are lacking. We aimed to propose a novel gait normalcy index based on dual task cost (NIDTC) and evaluate its validity and responsiveness for early-stage PD rehabilitation.MethodsThirty early-stage PD patients were recruited and randomly assigned to the AOT or active control (CON) group. The proposed NIDTC during straight walking and turning tasks and clinical scale scores were measured before and after 12 weeks of rehabilitation. The correlations between the NIDTCs and clinical scores were analyzed with Pearson correlation coefficient analysis to evaluate the construct validity. The rehabilitative changes were assessed using repeated-measures ANOVA, while the responsiveness of NIDTC was further compared by t tests.ResultsThe turning-based NIDTC was significantly correlated with multiple clinical scales. Significant group-time interactions were observed for the turning-based NIDTC (F = 4.669, p = 0.042), BBS (F = 6.050, p = 0.022) and PDQ-39 (F = 7.772, p = 0.011) tests. The turning-based NIDTC reflected different rehabilitation effects between the AOT and CON groups, with the largest effect size (p = 0.020, Cohen’s d = 0.933).ConclusionThe turning-based NIDTC exhibited the highest responsiveness for identifying gait automaticity improvement by providing a comprehensive representation of motor ability during dual tasks. It has great potential as a valid measure for early-stage PD diagnosis and rehabilitation assessment.Trial registration Chinese Clinical Trial Registry: ChiCTR2300067657

Improving Executive Function and Dual-Task Cost in Parkinson Disease: A Randomized Controlled Trial.

Dual-task walking is challenging for people with Parkinson disease (PD). Gait performance worsens while executing dual tasks, possibly due to a decline in executive function (EF). This study aimed to investigate the effects of dual-task training on EF and dual-task cost (DTC) in people with PD and to explore whether training-induced changes in EF were associated with changes in DTC. This study was a randomized controlled trial. A total of 28 people with PD participated. Participants were randomly assigned to the experimental group (dual-task training) and the control group (treadmill training). Both groups received a total of 16 training sessions during the 8weeks. Assessments were conducted at baseline and postintervention. Primary outcomes included EF and dual-task cost. Significant time-by-group interactions were found in executive function and DTC. The experimental group showed significant improvement in frontal assessment battery (FAB), trail-making test (TMT) part A, Stroop color and word test (SCWT), and DTC on speed in cognitive dual-task walking. There was a moderate to high correlation between the change values of the FAB, TMT part A, SCWT, and the change values of DTC in cognitive dual-task walking. Compared to treadmill training, dual-task training resulted in greater improvements in EF and DTC. Training-induced changes in EF were linked to changes in DTC when walking while performing a cognitive task but not when walking while performing a motor task. For more insights from the authors Supplemental Digital Content available at http://links.lww.com/JNPT/A485.

A useful cognitive motor dual task paradigm in prodromal and manifest Huntington’s disease

IntroductionIndividuals with Huntington's disease (HD) experience increased difficulty with balance throughout disease progression. Adding a simultaneous cognitive task to a balance assessment, referred to as a dual task (DT) paradigm, may have a deleterious effect on balance, which can be expressed in terms of a Dual Task Cost (DTC), relative to a single task (ST) condition. The aim of this study is to explore whether a cognitive-motor DT paradigm uncovers balance deficits in prodromal (Pro-HD) and manifest HD, compared to healthy adults (HA). MethodsBalance under ST and DT conditions was examined using the BTracks Balance Plate and Balance software in 30 individuals with HD, 17 individuals with Pro-HD, and 20 HA. During the DT condition, participants were simultaneously administered a version of the Paced Auditory Serial Addition Test (PASAT). DTC is calculated as the relative ratio of ST to DT, controlling for ST performance: DTC= (ST − DT)/ST x100. ResultsThe HA group performed significantly better than the HD group on both the ST and DT conditions (p < 0.01), while balance scores between the HA and the Pro-HD groups were not significantly different. The DTC scores, however, were significantly better in the HA compared to both the HD (p < 0.001) and Pro-HD (p < 0.05) groups. ConclusionOur findings indicate that the addition of a cognitive task interferes with participant's balance, reflecting real-life performance, and may have additional value for estimating transition to manifest disease, appraising fall risk, or serving as a valid outcome measure in observational and interventional trials in HD.

Hemodynamics of the Frontopolar and Dorsolateral Pre-Frontal Cortex in People with Multiple Sclerosis During Walking, Cognitive Subtraction, and Cognitive-Motor Dual-Task

Introduction Higher cortical activity has been observed in people with multiple sclerosis (pwMS) during walking and dual-tasking. However, further studies in overground walking and considering pre-frontal cortex (PFC) sub-areas are necessary. Objectives To investigate PFC activity during a cognitive-motor dual-task (DT) and its single component tasks, in combination with behavioral outcomes in pwMS. Methods Fifteen pwMS (EDSS 3.5 [2-5.5], 42 ± 11 years) and 16 healthy controls (HC, 45.2 ± 13.2 years) performed 3 conditions: single motor-walking (SWT), single cognitive – subtracting sevens (SCT), and a DT. Meters walked and the number of correct answers were obtained from which, respectively, the motor (mDTC) and cognitive (cDTC) DT costs were calculated. A functional Near-Infrared Spectroscopy covering the frontopolar and dorsolateral PFC (DLPFC) areas was used to concentration of relative oxyhemoglobin (ΔHbO2) and deoxyhemoglobin (ΔHHb) in the PFC. A repeated 2-way ANOVA (group × conditions) was used to compare ΔHbO2/ΔHHb and behavioral outcomes. Results PwMS walked shorter distances (P < .002) and answered fewer correct numbers (P < .03) than HC in all conditions, while cDTC and mDTC were similar between groups. PwMS presented higher ΔHbO2 in the frontopolar area than HC in the SWT (P < .001). HC increased ΔHbO2 in frontopolar during the SCT (P < .029) and DT (P < .037) compared with the SWT. Conclusion Higher frontopolar activity in pwMS compared to HC in the SWT suggests reduced gait automaticity. Furthermore, it seems that only HC increased neural activity in the frontopolar in the SCT and DT, which might suggest a limit of cognitive resources to respond to DT in pwMS.

Effects of word presentation during treadmill walking on episodic memory and gait

Entrainment emerges when oscillatory movements synchronize with environmental stimuli processing. The purpose of this experiment was to assess how cognitive-motor entrainment during a dual-task would influence the quality of gait and affect episodic long-term memory. Twenty-one participants (22.56 y/o; 64 % F) walked at preferred paces while listening to 40-item word lists. In separate sessions, unique word lists were presented predictably on every fourth stride, unpredictably related to stepping, or predictably while standing. Memory tests administered 24-hr after encoding revealed that predictable word presentation led to better free-recall performance than unpredicted (p = .044); recognition memory was not impacted. Gait phase parameters during the predicted condition were more stable than the unpredicted condition or baseline assessments. Cognitive-motor entrainment may alleviate dual-task costs and enhance memory retention.

A Novel Method to Measure Dual Task Capacity in Young Football Players: A Preliminary Study.

When deciding to return to sport, literature usually uses evaluations based on physical abilities. But, current literature urges us to use more than physical performance evaluations. Classical dual-task testing methods do not simulate in-game loads and cannot sufficiently measure football players' dual-task capacity. The purpose of our study was to create a dual-task test that would simulate football players' in- game situations and measure their capacity. Cross-sectional study. Football Pitch. Twenty-two football players (aged 17.37±0.52 years) who played in a professional club (U19, elite league) were recruited for our study. Novel dual task test with questions containing scenarios from a football game to cognitively load players, while they are performing modified t-test. After the warm-up period, participants attended four tests in random order: juggling (foot) test, speed dribbling test, long passing test, and 'novel dual-task test'. There was no significant relationship between physical performance parameters and dual task parameters (all ps>0.05). There was a significant increase in the completion time of modified t-test when performed under dual task condition (Z=-7.568, p<0.001). The increase in completion time was found as 2.14±1.29 seconds. This duration difference was calculated as 22.79±14.58%, as dual task cost. Our test provides a new method to measure athletes' dual task capacity, which is not related to physical performance and cannot be measured with current tests. This test also showed players with lower dual task ability could not keep up their performance under dual task conditions, such as passing a ball to a team-mate when being pressed by an opponent. Players with good dual task ability could maintain 1 their performance (got affected only up to 10%); players with poor dual task ability could not maintain their performance and got affected by up to 50% (with a mean of 22.79%).

Associations between white and grey matter damage and gait impairment in cerebral amyloid angiopathy

BackgroundCerebral amyloid angiopathy (CAA) is associated with white matter damage and neurodegeneration. Gait is impaired in CAA; however, the neural basis of this impairment is unclear. Research questionAre gait impairments in patients with CAA associated with altered cerebral white matter diffusivity and/or atrophy of cortical and subcortical grey matter. MethodsParticipants with CAA (n=29), Alzheimer’s disease (AD; n=16), and normal controls (n=47) were included. Gait was assessed using a 6 m walkway with parameters categorized into rhythm, pace, postural control, and variability domains. The dual-task cost (DTC) of gait speed was calculated for counting backwards, animal fluency, and serial sevens tasks. Whole-brain white matter disruption was quantified using the peak width of skeletonized mean diffusivity (PSMD), and thickness and volume of select cortical, subcortical, and cerebellar regions were quantified using FreeSurfer. ResultsIn CAA participants, associations were found between PSMD and pace (standardized parameter estimate (β), 95 % confidence interval (CI): 0.17, 0.03–0.32), and medial orbital frontal cortical thickness and counting backwards DTC (parameter estimate (PE), 95 % CI: −5.7 %/SD, −0.24 to −11.23). Across all groups, including CAA, associations were found between PSMD and pace, variability, counting backwards DTC, and animal fluency DTC; between frontal cortical thickness and pace, counting backwards DTC, and animal fluency DTC; between cortical regions affected by AD (inferior parietal cortex, inferior and middle temporal gyrus) and counting backwards DTC; and between thalamus volume and postural control. SignificanceReduced white matter structural integrity and grey matter loss is associated with poor overall gait performance in CAA, AD, and normal controls.

Lower-Limb Exoskeletons for Gait Training in Parkinson's Disease: The State of the Art and Future Perspectives.

Gait dysfunction (GD) is a common impairment of Parkinson's disease (PD), which negatively impacts patients' quality of life. Among the most recent rehabilitation technologies, a lower-limb powered exoskeleton (LLEXO) arises as a useful instrument for gait training in several neurological conditions, including PD. However, some questions relating to methods of use, achievable results, and usefulness compared to traditional rehabilitation methodologies still require clear answers. Therefore, in this review, we aim to summarise and analyse all the studies that have applied an LLEXO to train gait in PD patients. Literature research on PubMed and Scopus retrieved five articles, comprising 46 PD participants stable on medications (age: 71.7 ± 3.7 years, 24 males, Hoehn and Yahr: 2.1 ± 0.6). Compared to traditional rehabilitation, low-profile lower-limb exoskeleton (lp-LLEXO) training brought major improvements towards walking capacity and gait speed, while there are no clear major benefits regarding the dual-task gait cost index and freezing of gait symptoms. Importantly, the results suggest that lp-LLEXO training is more beneficial for patients with an intermediate-to-severe level of disease severity (Hoehn and Yahr > 2.5). This review could provide a novel framework for implementing LLEXO in clinical practise, highlighting its benefits and limitations towards gait training.

Comparison of single-and dual-task gait parameters of children with cancer and typically developing children

Purpose: This study aimed to compare single- and dual-task gait parameters between children with cancer (CC) and typically developing children (TDC). Methods: The gait parameters (gait speed, cadence, and stride length) assessed by the 10-meter walking test under single- and dual-task conditions and dual-task cost (DTC) was calculated. The t-test, Mann-Whitney U, and Pearson chi-square tests were used for comparisons. Purpose: This study aimed to compare single- and dual-task gait parameters between children with cancer (CC) and typically developing children (TDC). Methods: The gait parameters (gait speed, cadence, and stride length) assessed by the 10-meter walking test under single- and dual-task conditions and dual-task cost (DTC) was calculated. The t-test, Mann-Whitney U, and Pearson chi-square tests were used for comparisons. Results: The comparative-descriptive study was conducted with 49 children (14 females and 35 males) with a mean age of 12.45±2.71. The study participants consisted of two groups: CC (7 girls, 13 boys) and TDC (7 girls, 22 boys). The CC group exhibited lower gait speed (p

Cognitive Load and Dual-Task Performance in Individuals with and without Forward Head Posture.

Background: Recent studies have found forward head posture (FHP) is associated with altered physiology. There is a lack of research into whether FHP is associated with altered gait parameters when cognitively challenged. Our hypothesis is that individuals with FHP and those without will demonstrate different responses when undergoing dual-task assessment. Methods: Forty-five asymptomatic participants with FHP, defined as a craniovertebral angle (CVA) < 50°, were matched to forty-five participants with normal head posture (NHP) with a CVA > 55°. Participants walked along a 10 m platform under a control condition (no cognitive load) while an optical motion-capture system assessed gait kinematics. Secondly, participants were assessed under a dual-task cognitive load condition to identify the impact on gait kinematics. Results: Under the single-task condition, there were no significant differences for any gait parameter. In the dual-task condition, 12/13 gait parameters were significantly altered for the FHP vs. NHP group (p < 0.01). A calculation of the dual-task cost (DTC) percentage showed significant increases in all gait parameters in participants with FHP (p < 0.02). Correlations between the CVA and gait parameters were not significant for the single-task condition, but all gait parameters were correlated to CVA for the dual-task condition (p < 0.01). The correlation between CVA and DTC for all gait variables was significant (p < 0.04). Conclusions: This study demonstrates that FHP significantly increases the cognitive cost during walking, highlighting the importance of proper postural alignment for maintaining cognitive function under a dual-task condition.

The Effect of Total Knee Replacement on Dual-Task Gait Performance in Older Adults.

Total knee replacement (TKR) is a common solution for patients with advanced knee osteoarthritis (OA). Still, fall rates remain relatively high after surgery. TKR may alter pain and knee function, balance control, and proprioception. However, given the role of complex (dual-task) walking in fall prediction for older adults, it is unknown how TKR alters the attentional demand of walking in older adults. The goal of this study was to examine the effect of TKR on dual-task walking among older adults. Participants were evaluated 1month before surgery and 4.5months after surgery. Participants walked along an instrumented 7-meter path for 1minute with and without a cognitive task (serial-3 subtraction). Pain and knee function, knee proprioception, dynamic balance, and balance confidence, as well as dual-task costs (DTC) were compared before and after the surgery and factors associated with change in gait DTCs were assessed. Thirty-eight participants completed the study (age 72.6years, SD = 4.9; 11 men). A significant decrease in pain was found following TKR, with no change in balance, balance confidence, or proprioception. There were no differences in gait DTCs before and after the surgery. However, change in dynamic balance, specifically reactive postural control and dynamic gait, predicted changes in gait speed and stride time DTCs. The absence of an effect of TKR on gait DTCs can potentially underlie increased fall risk after TKR. Results from this study emphasize the significance of balance as a measure and focal point for rehabilitation after TKR. This study contributes to our understanding of the attentional cost of walking in people before and after TKR, as well as to factors associated with it. Results from this work can assist formulation of rehabilitation programs for people with knee OA.

Increased Auditory Dual Task Cost During Gait Initiation in Adult Patients With Persistent Concussion Symptoms

ObjectiveTo compare dual task cost (DTC) during gait initiation (GI) between a population of patients with persistent concussion symptoms (PCS) and age-matched healthy participants. DesignCohort study. SettingUniversity research center. ParticipantsA cohort sample including 15 participants with PCS (43.9±11.7y, 73.3% female) and 23 age-matched healthy participants (42.1±10.3y, 65.2% female) as controls. InterventionsParticipants were tested on a single occasion where they performed 5 trials of single task and 5 trials of dual task GI with 12-camera motion capture and 3 force plates. Main Outcome MeasuresThe dependent variables of interest were the DTC for the center of pressure (COP) displacement and velocity during the anticipatory postural adjustment (APA) phase, the COP-center of mass (COP-COM) separation, and the response accuracy during the auditory cognitive tasks. ResultsThere were significant group differences with worse DTC for the PCS participants in anterior (A)/posterior (P) displacement (PCS, −37.5±22.1%; Control, −9.7±39.2%; P=.016, d=0.874), APA medial (M)/lateral (L) velocity (PCS, −34.8±28.8%; Control, −17.0±40.21%; P=.041, d=0.866), and the peak COP-COM separation (PCS, −7.3±6.7%; Control, 0.6±6.5%; P=.023, d=1.200). There were no significant group differences in the APA A/P velocity (PCS, −38.8±33.1%; Control, −19.8±43.9%; P=.094), APA M/L displacement (PCS, −34.8±21.8%; Control, −10.6±25.3%; P=.313), or cognitive task performance (PCS, −2.7±10.8%; Control, −0.2±4.3%; P=.321). ConclusionsPCS participants had greater (worse) DTC during both the planning and execution of the task, with large effect sizes (d>0.80). PCS participants also used a posture-second strategy whereby attentional resources were inappropriately allocated to the cognitive task. These deficits may challenge a patient's ability to complete activities of daily living and limit their functional independence.