Single-task Conditions Research Articles

Effects of noninvasive brain stimulation on dual-task performance in different populations: A systematic review.

Increasing research has investigated the use of noninvasive brain stimulation (NIBS) on augmenting dual-task (DT) performance. To investigate the effects of NIBS on DT performance in different populations. Extensive electronic database search (from inception to November 20, 2022) was conducted in PubMed, Medline, Cochrane Library, Web of Science and CINAHL to identify randomized controlled trials (RCTs) that investigated the effects of NIBS on DT performance. Main outcomes were balance/mobility and cognitive function under both single-task (ST) and DT conditions. Fifteen RCTs were included, involving two types of intervention techniques: transcranial direct current stimulation (tDCS) (twelve RCTs) and repetitive transcranial magnetic stimulation (rTMS) (three RCTs); and four different population groups: healthy young adults, older adults, Parkinson's disease (PD), and stroke. For tDCS, under DT condition, significant improvement in speed was only observed in one PD and one stroke RCT, and stride time variability in one older adults RCT. Reduction in DTC in some gait parameters was demonstrated in one RCT. Only one RCT showed significant reduction in postural sway speed and area during standing under DT condition in young adults. For rTMS, significant improvements in fastest walking speed and time taken to Timed-up-and-go test under both ST and DT conditions were observed at follow-up in one PD RCT only. No significant effect on cognitive function in any RCT was observed. Both tDCS and rTMS showed promising effects in improving DT walking and balance performance in different populations, however, due to the large heterogeneity of included studies and insufficient data, any firm conclusion cannot be drawn at present.

Cortical Tracking of Continuous Speech Under Bimodal Divided Attention.

Speech processing often occurs amid competing inputs from other modalities, for example, listening to the radio while driving. We examined the extent to which dividing attention between auditory and visual modalities (bimodal divided attention) impacts neural processing of natural continuous speech from acoustic to linguistic levels of representation. We recorded electroencephalographic (EEG) responses when human participants performed a challenging primary visual task, imposing low or high cognitive load while listening to audiobook stories as a secondary task. The two dual-task conditions were contrasted with an auditory single-task condition in which participants attended to stories while ignoring visual stimuli. Behaviorally, the high load dual-task condition was associated with lower speech comprehension accuracy relative to the other two conditions. We fitted multivariate temporal response function encoding models to predict EEG responses from acoustic and linguistic speech features at different representation levels, including auditory spectrograms and information-theoretic models of sublexical-, word-form-, and sentence-level representations. Neural tracking of most acoustic and linguistic features remained unchanged with increasing dual-task load, despite unambiguous behavioral and neural evidence of the high load dual-task condition being more demanding. Compared to the auditory single-task condition, dual-task conditions selectively reduced neural tracking of only some acoustic and linguistic features, mainly at latencies >200 ms, while earlier latencies were surprisingly unaffected. These findings indicate that behavioral effects of bimodal divided attention on continuous speech processing occur not because of impaired early sensory representations but likely at later cognitive processing stages. Crossmodal attention-related mechanisms may not be uniform across different speech processing levels.

Does the fear of falls interfere with the task of boarding a bus in individuals with Parkinson’s disease?

BACKGROUND: Individuals with Parkinson’s disease (PD) have motor impairment that leads to the fear of falling, which limits functional independence. AIM: To correlate the fear of falling with cognitive function, handgrip strength, upper limb pulling force and functional execution time on the task of boarding a bus in individuals with PD. METHOD: A cross-sectional study involving 31 individuals with idiopathic PD. Assessments were performed with the Mini Mental State Examination (MMSE) and the Falls Efficacy Scale (FES-I). Handgrip strength and upper limb pulling force were measured using dynamometers installed on a bus prototype. Execution time was determined on the single task (ST), which consisted of climbing a bus, as well as a dual task (DT) (detecting specific letters from an audio recording during the task). Correlations between variables were determined using Pearson’s correlation test, with the significance level set at 5% (p <0.05). RESULTS: Moderate correlations were found between the FES-I score and the following variables: MVC for right handgrip strength (r = -0.491), left handgrip strength (r = -0.522), right arm pulling force (r = -0.522) and left arm pulling force (r = -0.563) as well as execution time on the ST (r = 0.514) and DT (r = 0.445). Moreover, a weak correlation was found between the total FES-I score and MMSE (r = -0.377). CONCLUSION: Greater concern with regards to falling was correlated with lower handgrip strength and upper limb pulling force, and a greater time spent boarding a bus under ST and DT conditions.

Inefficient frontal and parietal brain activation during dual-task walking in a virtual environment in older adults

Walking while performing an additional cognitive task (dual-task walking; DT walking) is a common yet highly demanding behavior in daily life. Previous neuroimaging studies have shown that performance declines from single-task (ST) to DT conditions are accompanied by increased prefrontal cortex (PFC) activity. This increment is particularly pronounced in older adults and has been explained either by compensation, dedifferentiation, or inefficient task processing in fronto-parietal circuits. However, there is only limited evidence for the hypothesized fronto-parietal activity changes measured under real-life conditions such as walking. In this study, we therefore assessed brain activity in PFC and parietal lobe (PL), to investigate whether higher PFC activation during DT walking in older adults is related to compensation, dedifferentiation, or neural inefficiency. Fifty-six healthy older adults (69.11 ± 4.19 years, 30 female) completed three tasks (treadmill walking at 1 m/s, Stroop task, Serial 3′s task) under ST and DT conditions (Walking + Stroop, Walking + Serial 3′s), and a baseline standing task. Behavioral outcomes were step time variability (Walking), Balance Integration Score BIS (Stroop), and number of correct calculations S3corr (Serial 3′s). Brain activity was measured using functional near-infrared spectroscopy (fNIRS) over ventrolateral and dorsolateral PFC (vlPFC, dlPFC) and inferior and superior PL (iPL, sPL). Neurophysiological outcome measures were oxygenated (HbO2) and deoxygenated hemoglobin (HbR). Linear mixed models with follow-up estimated marginal means contrasts were applied to investigate region-specific upregulations of brain activation from ST to DT conditions. Furthermore, the relationships of DT-specific activations across all brain regions was analyzed as well as the relationship between changes in brain activation and changes in behavioral performance from ST to DT. Data indicated the expected upregulation from ST to DT and that DT-related upregulation was more pronounced in PFC (particularly in vlPFC) than in PL regions. Activation increases from ST to DT were positively correlated between all brain regions, and higher brain activation changes predicted higher declines in behavioral performance from ST to DT. Results were largely consistent for both DTs (Stroop and Serial 3′s). These findings more likely suggest neural inefficiency and dedifferentiation in PFC and PL rather than fronto-parietal compensation during DT walking in older adults. Findings have implications for interpreting and promoting efficacy of long-term interventions to improve DT walking in older persons.

Influences of different cognitive loads on central common neural drives to the ankle muscles during dual-task walking

While dual-task walking with additional cognitive tasks may decrease walking performance, many studies have also shown increases in walking performance during dual tasks, especially as cognitive load increases. However, the neural mechanisms that cause changes in postural control during dual tasks according to the difference in cognitive load remain unclear. Therefore, this study aimed to investigate the influence of different cognitive loads on the neural control of muscle activity during dual-task walking using intra- and intermuscular coherence analyses. Eighteen healthy young adults were subjected to treadmill walking measurements in a single-task condition (normal walking without cognitive load) and two dual-task conditions (watching digits and digit 2-back task) with the measurements of reaction time to auditory stimulation. During walking with the digit 2-back task, stride-time variability was significantly reduced compared to that during normal walking, and reaction time was significantly delayed compared to those during normal walking and walking with watching digits. The peak value of the tibialis anterior intramuscular coherence in the beta band (15–35 Hz) significantly increased during walking with the digit 2-back task than that during walking with watching digits. The present results suggest that young adults can increase their central common neural drive and decrease their walking variability for concentration on cognitive tasks during dual-task walking.

The role of line-orientation processing in the production of the Poggendorff illusion: A dual-task study.

Using a dual-task paradigm, the present investigation examined whether processes related to line orientation play a critical role in the production of the Poggendorff illusion. In Experiment 1, we assessed the magnitude of the Poggendorff illusion under three different task conditions. In the single-task condition, participants were asked to report how they perceive the alignment of transversal lines in the Poggendorff figure. In two different dual-task conditions, the participants were asked to read aloud the time displayed on a digital or analogue clock while also performing the Poggendorff perception task. The method of constant stimuli was used to calculate the point of subjective equality (PSE) and bistability width values, which represent illusion strength and perceptual uncertainty, respectively. PSEs indicated that the magnitude of the illusion did not vary between single, dual-analogue, and dual-digital task conditions, which suggests that the additional demands placed by the dual tasks had no effect on the illusion strength. Perceptual uncertainty and clock-reading errors were greater in the dual-analogue task condition. Experiment 2 revealed that the analogue clockface was more difficult to read than the digital clockface. Based on these results, we conclude that having participants perform a secondary task does not influence the magnitude of the Poggendorff illusion.

Revised Dual Task Screen is a Valid Measure of Dual Task Performance: Developing a Motor and Cognitive Dual Task Measure with Healthy Female Athletes

Multitasking measures, such as dual task assessments, are particularly useful in detecting subtle deficits that can influence occupational performance after injuries, like sports-related concussion (SRC). In past work, our research team developed and revised a dual task assessment, the Dual Task Screen (DTS). Here, we evaluated nineteen healthy athletes using the revised DTS to address two specific research objectives. First, to replicate pilot study findings and demonstrate that the revised DTS is sensitive to dual task motor costs (i.e. poorer motor performance under dual task conditions, compared to single task conditions). Second, to evaluate if the revised DTS is sensitive to dual task cognitive costs (i.e. poorer cognitive performance under dual task conditions, compared to single task conditions). We confirmed that the revised DTS was sensitive to both dual task motor and cognitive costs; thus it is a valid measure of dual task performance. These positive findings support its prospective, future use by occupational therapists to evaluate multitasking performance after injuries, like SRC, or other injuries and illnesses that elicit deficits affecting optimal occupational performance.

Revised Dual Task Screen is a Valid Measure of Dual Task Performance: Developing a Motor and Cognitive Dual Task Measure with Healthy Female Athletes

Multitasking measures, such as dual task assessments, are particularly useful in detecting subtle deficits that can influence occupational performance after injuries, like sports-related concussion (SRC). In past work, our research team developed and revised a dual task assessment, the Dual Task Screen (DTS). Here, we evaluated nineteen healthy athletes using the revised DTS to address two specific research objectives. First, to replicate pilot study findings and demonstrate that the revised DTS is sensitive to dual task motor costs (i.e. poorer motor performance under dual task conditions, compared to single task conditions). Second, to evaluate if the revised DTS is sensitive to dual task cognitive costs (i.e. poorer cognitive performance under dual task conditions, compared to single task conditions). We confirmed that the revised DTS was sensitive to both dual task motor and cognitive costs; thus it is a valid measure of dual task performance. These positive findings support its prospective, future use by occupational therapists to evaluate multitasking performance after injuries, like SRC, or other injuries and illnesses that elicit deficits affecting optimal occupational performance.

The age-related contribution of cognitive function to dual-task gait in middle-aged adults in Spain: observations from a population-based study

Poor dual-task gait performance is associated with a risk of falls and cognitive decline in adults aged 65 years or older. When and why dual-task gait performance begins to deteriorate is unknown. This study aimed to characterise the relationships between age, dual-task gait, and cognitive function in middle age (ie, aged 40-64 years). We conducted a secondary analysis of data from community-dwelling adults aged 40-64 years that took part in the Barcelona Brain Health Initiative (BBHI) study, an ongoing longitudinal cohort study in Barcelona, Spain. Participants were eligible for inclusion if they were able to walk independently without assistance and had completed assessments of both gait and cognition at the time of analysis and ineligble if they could not understand the study protocol, had any clinically diagnosed neurological or psychiatric diseases, were cognitively impaired, or had lower-extremity pain, osteoarthritis, or rheumatoid arthritis that could cause abnormal gait. Stride time and stride time variability were measured under single-task (ie, walking only) and dual-task (ie, walking while performing serial subtractions) conditions. Dual-task cost (DTC; the percentage increase in the gait outcomes from single-task to dual-task conditions) to each gait outcome was calculated and used as the primary measure in analyses. Global cognitive function and composite scores of five cognitive domains were derived from neuropsychological testing. We used locally estimated scatterplot smoothing to characterise the relationship between age and dual-task gait, and structural equation modelling to establish whether cognitive function mediated the association between observed biological age and dual tasks. 996 people were recruited to the BBHI study between May 5, 2018, and July 7, 2020, of which 640 participants completed gait and cognitive assessments during this time (mean 24 days [SD 34] between first and second visit) and were included in our analysis (342 men and 298 women). Non-linear associations were observed between age and dual-task performance. Starting at 54 years, the DTC to stride time (β=0·27 [95% CI 0·11 to 0·36]; p<0·0001) and stride time variability (0·24 [0·08 to 0·32]; p=0·0006) increased with advancing age. In individuals aged 54 years or older, decreased global cognitive function correlated with increased DTC to stride time (β=-0·27 [-0·38 to -0·11]; p=0·0006) and increased DTC to stride time variability (β=-0·19 [-0·28 to -0·08]; p=0·0002). Dual-task gait performance begins to deteriorate in the sixth decade of life and, after this point, interindividual variance in cognition explains a substantial portion of dual-task performance. La Caixa Foundation, Institut Guttmann, and Fundació Abertis.

Feasibility and potential cognitive impact of a cognitive-motor dual-task training program using a custom exergame in older adults: A pilot study.

Dual-task training may be relevant and efficient in the context of active aging. An issue in training programs lies in enhancing the adherence of participants. This can potentially be improved using games as support. We designed and developed a custom interactive exergame in this way. The objective of this pilot study was to explore the potential use of this exergame and the feasibility of our intervention, including the level of safety and adherence. The result's trends on cognitive and motor capacities, as well as on the level of motivation for physical activity, fear of falling, and quality of life of participants, were also explored. Older adults aged 65 years or older were recruited and realized 30 min of supervised training in groups of 4, 2-3 times a week for 12 weeks. Exercises consisted of incorporated cognitive and motor dual tasks, with an increased difficulty over the weeks. Our program's safety, engagement, attendance, and completion levels were evaluated. Participants' postural control in single-task and dual-task conditions, as well as their performances in mental inhibition, flexibility, working memory, mobility, and postural control, and their levels of motivation for physical activity, fear of falling, and quality of life were also assessed. We realized a per protocol statistical analysis with a p-value set at 0.05. Thirty-nine participants (aged 84.6 ± 8.5 years) were recruited. No adverse events, and 89% adherence, 88% attendance, and 87% completion rates were observed. A potentially significant effect of our exergame on working memory in single-task conditions and on the cognitive aspect of dual-task conditions was also observed. We observed no differences in other parameters. Our exergame seemed feasible and safe and was enjoyed by participants, mainly due to the gamification of our training program. Moreover, our exergame may be efficient for cognitive training in older adults, as well as for the maintenance of motor functions, motivation for physical activity, fear of falling, and quality of life levels. This constitutes the first step for our solution with interesting results that need to be further studied.

The effects of cognitive impairment on the multi-scale dynamics of standing postural control during visual-search in older men.

Cognitive impairment disrupts postural control, particularly when standing while performing an unrelated cognitive task (i.e., dual-tasking). The temporal dynamics of standing postural sway are "complex," and such complexity may reflect the capacity of the postural control system to adapt to task demands. We aimed to characterize the impact of cognitive impairment on such sway complexity in older adults. Forty-nine older adult males (Alzheimer's disease (AD): n = 21; mild cognitive impairment (MCI): n = 13; cognitively-intact: n = 15) completed two 60-s standing trials in each of single-task and visual-search dual-task conditions. In the dual-task condition, participants were instructed to count the frequency of a designated letter in a block of letters projected on screen. The sway complexity of center-of-pressure fluctuations in anterior-posterior (AP) and medial-lateral (ML) direction was quantified using multiscale entropy. The dual-task cost to complexity was obtained by calculating the percent change of complexity from single- to dual-task condition. Repeated-measures ANOVAs revealed significant main effects of group (F > 4.8, p < 0.01) and condition (F = 7.7, p < 0.007) on both AP and ML sway complexity; and significant interaction between group and condition for ML sway complexity (F = 3.7, p = 0.03). The AD group had the lowest dual-task ML complexity, as well as greater dual-task cost to ML (p = 0.03) compared to the other two groups. Visual-search task accuracy was correlated with ML sway complexity in the dual-task condition (r = 0.42, p = 0.007), and the dual-task cost to ML sway complexity (r = 0.39, p = 0.01) across all participants. AD-related cognitive impairment was associated with a greater relative reduction in postural sway complexity from single- to dual-tasking. Sway complexity appears to be sensitive to the impact of cognitive impairment on standing postural control.

Factors infulencing gait in dual-task walking

Gait with an additional task commonly occurs in everyday life, e.g., simultaneously walking and talking on the phone. The dual-task paradigm (comparison of task performance efficiency under single-task conditions and simultaneous performance of both tasks) has found application in gait research. It is a test that allows assessing the quality of gait in clinical settings but also lets us analyse the quality of gait under the conditions of everyday life. It also allows the identification of people at risk of falling. A review of the available literature and research conducted at the Central Laboratory of Motion Analysis at AWF Krakow has been made, which may be useful for identifying factors that increase the risk of falls.

Different types of combined training programs to improve postural balance in single and dual tasks in children with intellectual disability.

The study explored the effects of two combined training (Strength-Proprioceptive versus Cognitive-Balance) programs on postural balance during single-task and dual-task conditions in children with intellectual disability. The postural balance and the second cognitive-task performances were evaluated before and after 8-week of training in two groups: Strength-Proprioceptive Group (n = 12) and Cognitive-Balance Group (n = 10). Results showed that, in both groups and regardless of the training effect, the postural balance performance was significantly (p < 0.05) altered in the dual-task condition compared to the single-task one. After-training session, postural balance performance was improved significantly (p < 0.001) for all task conditions. After training session, the second cognitive-task performance was improved in the Strength-Proprioceptive Group (p < 0.001) and Cognitive-Balance Groupe (p < 0.05). In conclusion, the combined training programs, Strength-Proprioceptive and Cognitive-Balance, improved postural balance performance in single-task and dual-task conditions in children with intellectual disability.

Interaction Between Memory Load and Experimental Design on Brain Connectivity and Network Topology.

The conventional approach to investigating functional connectivity in the block-designed study usually concatenates task blocks or employs residuals of task activation. While providing many insights into brain functions, the block design adds more manipulation in functional network analysis that may reduce the purity of the blood oxygenation level-dependent signal. Recent studies utilized one single long run for task trials of the same condition, the so-called continuous design, to investigate functional connectivity based on task functional magnetic resonance imaging. Continuous brain activities associated with the single-task condition can be directly utilized for task-related functional connectivity assessment, which has been examined for working memory, sensory, motor, and semantic task experiments in previous research. But it remains unclear how the block and continuous design influence the assessment of task-related functional connectivity networks. This study aimed to disentangle the separable effects of block/continuous design and working memory load on task-related functional connectivity networks, by using repeated-measures analysis of variance. Across 50 young healthy adults, behavioral results of accuracy and reaction time showed a significant main effect of design as well as interaction between design and load. Imaging results revealed that the cingulo-opercular, fronto-parietal, and default model networks were associated with not only task activation, but significant main effects of design and load as well as their interaction on intra- and inter-network functional connectivity and global network topology. Moreover, a significant behavior-brain association was identified for the continuous design. This work has extended the evidence that continuous design can be used to study task-related functional connectivity and subtle brain-behavioral relationships.

SPATIOTEMPORAL GAIT PARAMETERS, PELVIC MOVEMENTS AND PELVIC SYMMETRY DURING WALKING WITH SINGLE AND DUAL-TASKS IN INDIVIDUALS WITH CHRONIC IDIOPATHIC NECK PAIN

Purpose: Neck pain is associated with gait disturbances. The first aim of this study was to examine spatiotemporal gait parameters, pelvic movements and pelvic symmetry during single and dual task conditions in persons with Chronic Idiopathic Neck Pain (CINP) compared to healthy subjects (HS). The second aim was to investigate the relationship between disability and gait in persons with CINP.&#x0D; Methods: Thirty-one individuals with CINP (mean age 22.06±1.38 years, range 18-56 years) and 24 HS (mean age 22.60±1.51 years, range 18-43 years) participated in the study. CINP group completed Neck Disability Index. All participants performed 10-meter walking test in two conditions: (1) walking with head straight at usual speed, (2) walking with head straight at usual speed while carrying a tray. The BTS G-Walk wearable sensor was used to assess spatiotemporal parameters (speed, cadence, step length), pelvic movements (tilt, obliquity, rotation), and pelvic symmetry.&#x0D; Results: During single task gait, the CINP group had significantly lower walking speed, shorter stride length and worse pelvic tilt symmetry (p

Association between measures of cognitive function on physical function in novice users of a lower limb prosthesis

BackgroundCognitive impairment is prevalent in people with lower limb amputations (PLLA) and is associated with adverse outcomes, such as falls and worse rehabilitation outcomes. Physical function tests are essential to examine abilities; however, no research in PLLA has clarified the magnitude of cognitive demands amongst available tests in users novice at walking with a prosthesis. Research questionIs there an association between cognitive and physical function for PLLA novice at walking with a prosthesis? MethodsPeople from inpatient prosthetic rehabilitation were recruited. Inclusion criteria were: age ≥ 50 years, unilateral transtibial amputation and able to walk independently. Gait velocity and the L Test under single-task (usual) and dual-task (walking while counting backwards) conditions assessed functional mobility. The Four Square Step Test (FSST) examined dynamic balance. The Montreal Cognitive Assessment (MoCA) and the Trail Making Test (TMT-B) assessed global cognitive status and executive function, respectively. Multivariable linear regressions evaluated the association of cognition on physical function. ResultsTwenty-two people participated (age: 62.3 ± 8.9 years, male: 68.18%). The mean MoCA score was 26.23 ± 2.90. A 1-point MoCA increase was independently associated with faster gait velocity (cm/s) [single-task: 5.45 (95%CI: 2.35–8.54, AdjR2 =0.46), dual-task: 5.04 (95%CI: 1.33–8.75, AdjR2 =0.20) and a quicker L Test (s) [single-task: − 4.75 (95%CI: 7.22–2.28, AdjR2 =0.45), dual-task: − 5.27 (95%CI: 8.74–1.80, AdjR2 =0.38)]. A 1-second TMT-B increase was also independently associated with worse L Test performance [single-task: 0.21 s (95%CI: 0.03–0.39, AdjR2 =0.20), dual-task: 0.29 s (95%CI: 0.06–0.51, AdjR2 =0.30)]. No association was observed between MoCA or TMT-B on the FSST (p > 0.13). SignificanceBetter global cognitive function and executive function were independently associated with faster gait velocity and improved functional mobility, but not dynamic balance. The present study demonstrates a unique relationship between cognition and physical function that warrants further research on the cognitive demands among clinical tests of physical function in PLLA.

The effect of single and dual-task balance exercises on balance performance in older adult patients with degenerative lumbar spinal stenosis: A randomized controlled trial

BackgroundLumbar Spinal Stenosis (LSS) may present with balance disorder and risk of falling as a result of posture problems. The aim of the present study was to compare the effects of single-task and dual-task balance exercise programs on balance performance and activity-specific balance confidence in adults with LSS. MethodsForty-three patients with LSS over the age of 65 were randomly divided into 2 groups as single-task balance training (group 1, n=21) and double-task balance training (group 2, n=22). Patients in both groups were given exercises by an experienced physiotherapist. Only balance exercises were applied to Group 1 under single task conditions, and Group 2 performed balance exercises accompanied by predetermined cognitive tasks. Patients were evaluated with Berg balance scale (BBS), timed up and go (TUG) test, and 10-meter walking test for single and dual tasks, Tinetti balance and gait test, single leg stance test, and activities-specific balance confidence (ABC) scale at baseline and at the end of four weeks. The Mann-Whitney U Test was used to compare the pre- and post-treatment differences in the groups. ResultsDemographic data did not show any statistical significance between the two groups. When the pre- and post-treatment differences of the 10-meter walk test were compared between the single-task training group and the dual-task training group, it was observed that there was a difference in favor of the dual-task training group in the 10-meter walk test was performed separately in the single-task and dual-task training group (p < 0.05). When the differences before and after treatment were compared, no difference was observed in the BBS, TUG, Tinetti balance and gait test, single leg stance test, and ABC scale data between the groups (p > 0.05). ConclusionSingle- and dual-task exercises significantly improved static balance, dynamic balance, and activity-specific balance confidence in older adults with spinal stenosis. However, the dual-task exercise program was superior to the single-task exercise program in improving 10-meter walk test scores and walking speed, with or without cognitive dual-tasking.

Including cognitive assessments with functional testing predicts capabilities relevant to everyday walking in older adults

BackgroundDual-task (DT) testing reflects real-world walking demands in older adults but is not always feasible to perform in clinic. Whether clinical measures that predict single-task (ST) performance also predict DT performance or dual-task effects (DTEs) has not been fully explored. Research questionWhat are the relationships between cognitive performance, functional mobility, and self-reported physical activity and balance confidence and ST and DT Gait Speed and Cognitive Reaction Time, as well as DTEs on Gait Speed (DTEGS) and Cognitive Reaction Time (DTERT), in older adults? MethodsSixty-two older adults (71.5 ± 7.1 years, 17 males) completed cognitive performance, functional mobility, and self-report physical activity and balance confidence assessments. Three 1-min trials were performed: 1) ST Cognition (clock task), 2) ST Gait and 3) DT Cognition + Gait, with Cognitive Reaction Time (recorded during clock task performance via DirectRT) and Gait Speed (measured during walking trial via APDM system) recorded, and DTEGS and DTERT calculated, as the cognitive and gait outcomes. Six multivariate regressions were conducted to test whether cognitive performance, functional mobility, and self-report assessments predicted Gait Speed and Cognitive Reaction Time in ST and DT conditions and DTEs. ResultsThe Comprehensive Trail Making Test (CTMT) predicted Reaction Time in ST cognitive (β = − 0.525, p = .003) and DT (β = − 0.510, p = .006) trials. The Physical Activity Scale for the Elderly (PASE) predicted DTERT (β = − 0.397, p = .008). The 10-Meter Walk Test (10MWT) predicted Gait Speed in ST gait (β = 0.692, p < .001) and DT (β = 0.715, p < .001) trials. The Four Square Step Test (FSST) predicted ST Gait Speed (β = − 0.233, p = .034). The Montreal Cognitive Assessment (MoCA) (β = 0.293, p = .027), 10MWT (β = 0.322, p = .046), and the FSST (β = 0.378, p = .019) predicted DTEGS. SignificanceThe 10MWT, CTMT, and MoCA can be easily implemented in the clinic and may be good choices to assess cognitive and functional abilities necessary for ambulation in older adults.

Cognitive load, working memory capacity and driving performance: A preliminary fNIRS and eye tracking study

A common cause of road traffic incidents is driver distraction, which can occur when the driver’s attention is engaged in a concurrent secondary task. However, the relationship between cognitive demands, individual differences in working memory capacity and driving performance has received little research attention. Using a fixed-base driving simulator, the aim of this study was to use a combination of self-report, functional near infrared spectroscopy (fNIRS) and mobile eye tracking data to investigate the impact of cognitive load on drivers’ gaze behaviour and driving performance, as well as explore the relationship between working memory capacity and driving performance under increased cognitive load. Twenty-one participants with a range of driving experiences (e.g., 0–14 h per week) completed a simulated driving task in a simple environment (i.e., country highway) under single-task (driving only) and dual-task (driving + modified 2-back task) conditions. Cognitive load was assessed via fNIRS data that manifested as changes in regional oxygen saturation (rSO2) in prefrontal cortex as well as self-report data of perceived mental effort. Participants’ working memory capacity was assessed using the Operation Span Task. Findings showed that prefrontal rSO2 and perceived mental effort was significantly greater under dual-task conditions compared to the single-task condition. In the dual-task condition, participants’ gaze dwelled for longer on the road and they made fewer fixations, of longer durations. Participants were able to maintain driving performance in this condition, although this was at the expense of secondary task performance. Interestingly, driving infractions under dual-task conditions were negatively correlated with participants’ working memory capacity. The findings suggest that engaging with distracting secondary tasks while driving may increase drivers’ cognitive load and change their gaze behaviour. Driving performance can seemingly be maintained under such conditions, but this may be partly determined by the driver’s working memory capacity.

Gait variability predicts cognitive impairment in older adults with subclinical cerebral small vessel disease.

Advanced methods of gait research, including approaches to quantify variability, and orderliness/regularity/predictability, are increasingly used to identify patients at risk for the development of cognitive impairment. Cerebral small vessel disease (CSVD) is highly prevalent in older adults and is known to contribute to the development of vascular cognitive impairment and dementia (VCID). Studies in preclinical models demonstrate that subclinical alterations precede CSVD-related cognitive impairment in gait coordination. In humans, CSVD also associates with gait abnormalities. The present study was designed to test the hypothesis that increased gait variability and gait asymmetry predict a decline in cognitive performance in older adults with CSVD. To test this hypothesis, we compared cognitive performance and gait function in patients with CSVD (age: 69.8 ± 5.3 years; n = 11) and age- and sex-matched control participants (age: 70.7 ± 5.8 years; n = 11). Based on imaging findings, patients with CSVD were identified [presence of white matter hyperintensities plus silent brain infarcts and/or microhemorrhages on magnetic resonance imaging (MRI) assessment]. Cognitive performance was assessed using the Cambridge Neuropsychological Test Automated Battery (CANTAB). Gait parameters were measured during the single and dual tasks, during which participants, in addition to the motor task, completed a series of mental arithmetic calculations. Spatial and temporal parameters of gait variability, symmetry, and permutation entropy were determined using a pressure-sensitive gait mat during single and dual cognitive task conditions. Patients with CSVD exhibited lower performance in a visual learning test (p = 0.030) and in a sustained attention test (p = 0.007). CSVD also affected step time variability (p = 0.009) and step length variability (p = 0.017). Step lengths of CSVD participants were more asymmetric (p = 0.043) than that of controls, while the two groups were statistically similar regarding step time symmetry and entropy of step time and length. Gait variability was inversely associated with sustained attention, especially among CSVD patients, and this relationship was significantly different between the two groups. The association of sustained attention with gait symmetry was also significantly different between the two groups. Our findings provide additional evidence in support of the concept that increased gait variability and asymmetry may predict cognitive impairment in older adults with CSVD.