The role of higher-level cognitive function in gait: executive dysfunction contributes to fall risk in Alzheimer's disease

Toward Development of a Novel Proprioceptive Trail-Making Test: Comparing Healthy Dancers and Non-Dancers

There is a pressing need for ecologically valid versions of traditional neuropsychological tests indexing executive function (EF), such as the Trail-Making Task (TMT), that incorporate movement and bodily awareness in healthy participants with varying abilities. We designed a proprioceptive version of the TMT (pTMT) that involved coordinated gross motor movement and proprioceptive awareness to investigate whether this measure of visual attention, task switching, and working memory positively correlated with a computerized version of the TMT (the dTMT). We aimed to establish the initial validity of our proprioceptive TMT (pTMT) by comparing performances on the dTMT and pTMT among a cohort of 36 healthy participants (18 dancers, 18 non-dancers; M age = 22, SD = 5.27; 64% female) anticipating that dancers would express higher intrinsic bodily awareness than non-dancers. Results revealed a mild to moderate but statistically significant positive correlation between dTMT and pTMT completion times [part A: r (36) = .33, p = .04; part B: r (36) = .37, p = .03] and numbers of errors [part B: r (36) = .41, p = .01] across both participant groups. These data suggest partial measurement convergence between these two TMT versions. Relative to non-dancers, dancers exhibited a higher level of performance (likely due to their better proprioceptive ability) through their faster completion times on dTMT-B [t (34) = 3.81, p = .006, d = 1.27] and pTMT-B [t (34) = 2.97, p = .005, d = .99], and their fewer errors on dTMT-B [t (34) = 2.93, p = .006, d = 1.0]. By identifying cognitive differences between these different groups of healthy individuals, our data contribute to both a theoretical understanding and the initial development of gross motor movement-based cognitive assessments, providing a path toward the further refinement of an ecologically valid full-body TMT.

Mobile neuroimaging: What we have learned about the neural control of human walking, with an emphasis on EEG-based research

Our understanding of the neural control of human walking has changed significantly over the last twenty years and mobile brain imaging methods have contributed substantially to current knowledge. High-density electroencephalography (EEG) has the advantages of being lightweight and mobile while providing temporal resolution of brain changes within a gait cycle. Advances in EEG hardware and processing methods have led to a proliferation of research on the neural control of locomotion in neurologically intact adults. We provide a narrative review of the advantages and disadvantages of different mobile brain imaging methods, then summarize findings from mobile EEG studies quantifying electrocortical activity during human walking. Contrary to historical views on the neural control of locomotion, recent studies highlight the widespread involvement of many areas, such as the anterior cingulate, posterior parietal, prefrontal, premotor, sensorimotor, supplementary motor, and occipital cortices, that show active fluctuations in electrical power during walking. The electrocortical activity changes with speed, stability, perturbations, and gait adaptation. We end with a discussion on the next steps in mobile EEG research.

White matter fibre density in the brain's inhibitory control network is associated with falling in low activity older adults

Recent research has indicated that the relationship between age-related cognitive decline and falling may be mediated by the individual's capacity to quickly cancel or inhibit a motor response. This longitudinal investigation demonstrates that higher white matter fibre density in the motor inhibition network paired with low physical activity was associated with falling in elderly participants. We measured the density of white matter fibre tracts connecting key nodes in the inhibitory control network in a large sample (n = 414) of older adults. We modelled their self-reported frequency of falling over a 4-year period with white matter fibre density in pathways corresponding to the direct and hyperdirect cortical-subcortical loops implicated in the inhibitory control network. Only connectivity between right inferior frontal gyrus and right subthalamic nucleus was associated with falling as measured cross-sectionally. The connectivity was not, however, predictive of future falling when measured 2 and 4 years later. Higher white matter fibre density was associated with falling, but only in combination with low levels of physical activity. No such relationship existed for selected control brain regions that are not implicated in the inhibitory control network. Albeit statistically robust, the direction of this effect was counterintuitive (more dense connectivity associated with falling) and warrants further longitudinal investigation into whether white matter fibre density changes over time in a manner correlated with falling, and mediated by physical activity.

Falls and Alzheimer Disease

Falls are the leading cause of injury, disability, and injury-related mortality in the older adult population. Older adults with Alzheimer disease (AD) are over twice as likely to experience a fall compared to cognitively normal older adults. Intrinsic and extrinsic fall risk factors may influence falls during symptomatic AD; intrinsic factors include changes in cognition and impaired functional mobility, and extrinsic factors include polypharmacy and environmental fall hazards. Despite many known fall risk factors, the high prevalence of falls, and the presence of effective fall prevention interventions for older adults without cognitive impairment, effective fall prevention interventions for older adults with AD to date are limited and inconclusive. Falls may precede AD-related cognitive impairment during the preclinical phase of AD, though a narrow understanding of fall risk factors and fall prevention interventions for older adults with preclinical AD limits clinical treatment of falls among cognitively normal older adults with preclinical AD. This mini review explores fall risk factors in symptomatic AD, evidence for effective fall prevention interventions in symptomatic AD, and preclinical AD as an avenue for future falls research, including recommendations for future research directions to improve our understanding of falls and fall risk during preclinical AD. Early detection and tailored interventions to address these functional changes are needed to reduce the risk of falls for those at risk for developing AD. Concerted efforts should be dedicated to understanding falls to inform precision fall prevention strategies for this population.

Reduced Proactive and Reactive Cognitive Flexibility in Older Adults Underlies Performance Costs During Dual-Task Walking: A Mobile Brain/Body Imaging (MoBI) Study

Age-related reductions in cognitive flexibility may limit modulation of control processes during systematic increases to cognitive-motor demands, exacerbating dual-task costs. In this study, behavioral and neurophysiologic changes to proactive and reactive control during progressive cognitive-motor demands were compared across older and younger adults to explore the basis for age-differences in cognitive-motor interference (CMI). 19 younger (19 - 29 years old, mean age = 22.84 +/- 2.75 years, 6 male, 13 female) and 18 older (60 - 77 years old, mean age = 67.89 +/- 4.60 years, 9 male, 9 female) healthy adults completed cued task-switching while alternating between sitting and walking on a treadmill. Gait kinematics, task performance measures, and brain activity were recorded using electroencephalography (EEG) based Mobile Brain/Body Imaging (MoBI). Response accuracy on easier trial types improved in younger, but not older adults when they walked while performing the cognitive task. As difficulty increased, walking provoked accuracy costs in older, but not younger adults. Both groups registered faster responses and reduced gait variability during dual-task walking. Older adults exhibited lower amplitude modulations of proactive and reactive neural activity as cognitive-motor demands systematically increased, which may reflect reduced flexibility for progressive preparatory and reactive adjustments over behavioral control.

Mechanistic description of spontaneous loss of memory persistent activity based on neuronal synaptic strength

Persistent neural activity associated with working memory (WM) lasts for a limited time duration. Current theories suggest that its termination is actively obtained via inhibitory currents, and there is currently no theory regarding the possibility of a passive memory-loss mechanism that terminates memory persistent activity. Here, we develop an analytical-framework, based on synaptic strength, and show via simulations and fitting to wet-lab experiments, that passive memory-loss might be a result of an ionic-current long-term plateau, i.e., very slow reduction of memory followed by abrupt loss. We describe analytically the plateau, when the memory state is just below criticality. These results, including the plateau, are supported by experiments performed on rats. Moreover, we show that even just above criticality, forgetfulness can occur due to neuronal noise with ionic-current fluctuations, yielding a plateau, representing memory with very slow decay, and eventually a fast memory decay. Our results could have implications for developing new medications, targeted against memory impairments, through modifying neuronal noise.

Alzheimer's disease phenotype based upon the carrier status of the apolipoprotein E ɛ4 allele

The apolipoprotein E ɛ4 allele (APOE4) is universally acknowledged as the most potent genetic risk factor for Alzheimer's disease (AD). APOE4 promotes the initiation and progression of AD. Although the underlying mechanisms are unclearly understood, differences in lipid-bound affinity among the three APOE isoforms may constitute the basis. The protein APOE4 isoform has a high affinity with triglycerides and cholesterol. A distinction in lipid metabolism extensively impacts neurons, microglia, and astrocytes. APOE4 carriers exhibit phenotypic differences from non-carriers in clinical examinations and respond differently to multiple treatments. Therefore, we hypothesized that phenotypic classification of AD patients according to the status of APOE4 carrier will help specify research and promote its use in diagnosing and treating AD. Recent reviews have mainly evaluated the differences between APOE4 allele carriers and non-carriers from gene to protein structures, clinical features, neuroimaging, pathology, the neural network, and the response to various treatments, and have provided the feasibility of phenotypic group classification based on APOE4 carrier status. This review will facilitate the application of APOE phenomics concept in clinical practice and promote further medical research on AD.

Using dual-task gait to recognize Alzheimer's disease and mild cognitive impairment: a cross-sectional study

Background

Gait is a potential diagnostic tool for detecting mild cognitive impairment (MCI) and Alzheimer's disease (AD). Nevertheless, little attention has been paid to arm movements during walking, and there is currently no consensus on gait asymmetry. Therefore, in this study, we aimed to determine whether arm motion and gait asymmetry could be utilized for identifying MCI and AD.

Methods

In total, 102 middle-aged and elderly individuals were included in the final analysis and were assigned to the following three groups: AD (n = 27), MCI (n = 35), and a normal control group (n = 40). Gait and cognitive assessments were conducted for all participants. Gait detection included a single-task gait with free-speed walking and a dual-task gait with adding a cognitive task of successive minus seven to walking. Original gait parameters were collected using a wearable device featuring the MATRIX system 2.0. Gait parameters were shortened to several main gait domains through factor analysis using principal component extraction with varimax rotation. Subsequently, the extracted gait domains were used to differentiate the three groups, and the area under the receiver operating characteristic curve was calculated.

Results

Factor analysis of single-task gait identified five independent gait domains: rhythm symmetry, rhythm, pace asymmetry, arm motion, and variability. Factor analysis of the dual-task gait identified four gait domains: rhythm, variability, symmetry, and arm motion. During single-task walking, pace asymmetry was negatively correlated with MoCA scores and could distinguish between the AD group and the other two groups. Arm motion was not associated with MoCA scores, and did not exhibit adequate discrimination in either task.

Conclusion

Currently, there is no reliable evidence suggesting that arm motion can be used to recognize AD or MCI. Gait asymmetry can serve as a potential gait marker for the auxiliary diagnosis of AD but not for MCI.

Gait Abnormalities in Children with Phelan-McDermid Syndrome

Background: Phelan-McDermid syndrome is a genetic disorder caused by haploinsufficiency of the SHANK3 gene on chromosome 22q13.3 and is characterized by autism spectrum disorder, intellectual disability, speech and language abnormalities, hypotonia, and mild dysmorphic features. Early literature in Phelan-McDermid syndrome did not include gait abnormalities as part of the syndrome although recent prospective studies report that the prevalence of gait abnormalities ranges from 55% to 94%. We compared gait abnormalities in individuals with Phelan-McDermid syndrome, idiopathic autism spectrum disorder, and typically developing controls, and explored associations between gait abnormalities, autism spectrum disorder, and intellectual functioning. Method: The study cohort consists of 67 participants between the ages of 3 and 18 years, divided into 3 groups: Phelan-McDermid syndrome (n  =  46), idiopathic autism spectrum disorder (n  =  11), and typically developing controls (n  =  10). Gait was recorded using a video camera and scored across 26 gait features using a "Gait Clinical Observations scale" designed specifically for this study. Results: Gait abnormalities were significantly higher in the Phelan-McDermid syndrome group as compared to idiopathic autism spectrum disorder or typically developing controls. The number of gait abnormalities across groups was also significantly correlated with Intellectual Quotient/Developmental Quotient (IQ/DQ). In analysis of covariance including IQ/DQ, the effect of group was not significant, but the effect of IQ/DQ was significant. Conclusions: Overall differences in gait abnormalities were determined by the degree of intellectual disability, which was significantly higher in Phelan-McDermid syndrome.

Cognitive impairment is associated with gait variability and fall risk in amyotrophic lateral sclerosis

BACKGROUND

In amyotrophic lateral sclerosis (ALS), gait abnormalities contribute to poor mobility and represent a relevant risk for falls. To date, gait studies in ALS patients have focused on the motor dimension of the disease, underestimating the cognitive aspects.

METHODS

Using a wearable gait analysis device, we compared gait patterns in ambulatory ALS patients with mild cognitive impairment (ALS MCI+; n = 18), and without MCI (ALS MCI-; n = 24), and healthy subjects (HS; n = 16) under two conditions: (1) normal gait (single task) and (2) walking while counting backward (dual task). Finally, we examined if the occurrence and number of falls in the 3 months following the baseline test were related to cognition.

RESULTS

In the single task condition, ALS patients, regardless of cognition, displayed higher gait variability than HS, especially for stance and swing time (p < 0.001). The dual task condition revealed additional differences in gait variability parameters between ALS MCI+ and ALS MCI- for cadence (p = 0.005), stance time (p = 0.04), swing time (p = 0.04) and stability index (p = 0.02). Moreover, ALS MCI+ showed a higher occurrence (p = 0.001) and number of falls (p < 0.001) at the follow-up. Regression analyses demonstrated that MCI condition predicted the occurrence of future falls (β = 3.649; p = 0.01) and, together with executive dysfunction, was associated with the number of falls (cognitive impairment: β = 0.63; p < 0.001; executive dysfunction: β = 0.39; p = 0.03), regardless of motor impairment at clinical examination.

CONCLUSION

In ALS, MCI is associated with exaggerated gait variability and predicts the occurrence and number of short-term falls.

Minding your steps: a cross-sectional pilot study using foot-worn inertial sensors and dual-task gait analysis to assess the cognitive status of older adults with mobility limitations

BACKGROUND

Cognitive impairment is a critical aspect of our aging society. Yet, it receives inadequate intervention due to delayed or missed detection. Dual-task gait analysis is currently considered a solution to improve the early detection of cognitive impairment in clinical settings. Recently, our group proposed a new approach for the gait analysis resorting to inertial sensors placed on the shoes. This pilot study aimed to investigate the potential of this system to capture and differentiate gait performance in the presence of cognitive impairment based on single- and dual-task gait assessments.

METHODS

We analyzed demographic and medical data, cognitive tests scores, physical tests scores, and gait metrics acquired from 29 older adults with mobility limitations. Gait metrics were extracted using the newly developed gait analysis approach and recorded in single- and dual-task conditions. Participants were stratified into two groups based on their Montreal Cognitive Assessment (MoCA) global cognitive scores. Statistical analysis was performed to assess differences between groups, discrimination ability, and association of gait metrics with cognitive performance.

RESULTS

The addition of the cognitive task influenced gait performance of both groups, but the effect was higher in the group with cognitive impairment. Multiple dual-task costs, dual-task variability, and dual-task asymmetry metrics presented significant differences between groups. Also, several of these metrics provided acceptable discrimination ability and had a significant association with MoCA scores. The dual-task effect on gait speed explained the highest percentage of the variance in MoCA scores. None of the single-task gait metrics presented significant differences between groups.

CONCLUSIONS

Our preliminary results show that the newly developed gait analysis solution based on foot-worn inertial sensors is a pertinent tool to evaluate gait metrics affected by the cognitive status of older adults relying on single- and dual-task gait assessments. Further evaluation with a larger and more diverse group is required to establish system feasibility and reliability in clinical practice.

TRIAL REGISTRATION

ClinicalTrials.gov (identifier: NCT04587895).

Immersive Virtual Reality Reaction Time Test and Relationship with the Risk of Falling in Parkinson's Disease

Immersive virtual reality (IVR) uses customized and advanced software and hardware to create a digital 3D reality in which all of the user's senses are stimulated with computer-generated sensations and feedback. This technology is a promising tool that has already proven useful in Parkinson's disease (PD). The risk of falls is very high in people with PD, and reaction times and processing speed may be markers of postural instability and functionality, cognitive impairment and disease progression. An exploratory study was conducted to explore the feasibility of reaction time tests performed in IVR as predictors of falls. A total of 26 volunteers (79.2% male; 69.73 ± 6.32 years) diagnosed with PD (1.54 ± 0.90 H&Y stage; 26.92 ± 2.64 MMSE) took part in the study. IVR intervention was feasible, with no adverse effects (no Simulator Sickness Questionnaire symptoms). IVR reaction times were related (Spearman's rho) to functionality (timed up and go test (TUG) (rho = 0.537, p = 0.005); TUG-Cognitive (rho = 0.576, p = 0.020); cognitive impairment mini mental state exam (MMSE) (rho = -0.576, p = 0.002)) and the years of the patients (rho = 0.399, p = 0.043) but not with the first PD symptom or disease stage. IVR test is a complementary assessment tool that may contribute to preventing falls in the proposed sample. Additionally, based on the relationship between TUG and reaction times, a cut-off time is suggested that would be effective at predicting the risk of suffering a fall in PD patients using a simple and quick IVR test.

A normative study of the gait features measured by a wearable inertia sensor in a healthy old population

BACKGROUND

Gait function impairments are associated with the risk of various medical conditions in older adults. As gait function declines with advancing age, normative data are required for proper interpretation of gait function in older adults.

RESEARCH PURPOSE

This study aimed to construct age-stratified normative data of non-dimensionally normalized temporal and spatial gait features in healthy older adults.

METHODS

We recruited 320 community-dwelling healthy adults aged 65 years or older from two prospective cohort studies. We stratified them into four age groups (65-69, 70-74, 75-79, and 80-84 years). Each age group comprised 40 men and 40 women. We obtained six gait features (cadence, step time, step time variability, step time asymmetry, gait speed, and step length) using a wearable inertia measurement unit attached on the skin overlying L3-L4 on the back. To mitigate the influence of body shape, we non-dimensionally normalized the gait features into unitless values using height and gravity.

RESULT

The effect of age group was significant in all raw gait features (p < 0.001 for step time variability, speed and step length; p < 0.05 for cadence, step time and step time asymmetry), and that of sex was significant in the five raw gait features, except for step time asymmetry(p < 0.001 for cadence, step time, speed, and step length; p < 0.05 for step time asymmetry). When gait features were normalized, the effect of age group remained (p < 0.001 for all gait features), whereas that of sex disappeared (p > 0.05 for all gait features).

SIGNIFICANCE

Our dimensionless normative data on gait features may be useful in comparative studies of gait function between sexes or ethnicities with different body shapes.

The influence of altered foot placement and cognitive load on balance control during walking in healthy young adults

BACKGROUND

Clinical populations often walk with altered foot placement, which can adversely affect balance control. However, it is unknown how balance control during walking is influenced when combining a cognitive load with altered foot placement.

RESEARCH QUESTION

Is balance control during walking adversely affected by the combination of a more complex motor task, such as walking with altered foot placements, with a cognitive load?

METHODS

Fifteen young healthy adults walked on a treadmill with and without a spelling cognitive load during normal walking, with step width targets (self-selected width, narrow, wide and extra wide), or with step length targets (self-selected length, short and long).

RESULTS

Cognitive performance, measured by correct spelling response rate, decreased from self-selected (2.407 ± 0.6 letters/s) to the extra wide width (2.011 ± 0.5 letters/s). The addition of the cognitive load caused a decrease in frontal plane balance control across all step lengths (15% change) and at the wider step widths (16% change), but only caused a slight decrease in the sagittal plane for the short step length (6.8% change).

SIGNIFICANCE

These results suggest that when combining a cognitive load with walking at non-self-selected widths, a threshold exists at wider steps where attentional resources become insufficient and balance control and cognitive performance decrease. Because decreased balance control increases the risk of falling, these results have implications for clinical populations who often walk with wider steps. Furthermore, the lack of changes to sagittal plane balance during altered step length dual-tasks further supports that frontal plane balance requires more active control.

Effectiveness of physical exercise at improving functional capacity in older adults living with Alzheimer's disease: a systematic review of randomized controlled trials

PURPOSE

To investigate the effects of physical exercise at improving functional capacity in older adults living with Alzheimer's disease (AD).

METHODS

Medline, Embase, Web of Science, The Cochrane Library, Lilacs, and PEDro were searched from inception until January 2021. Randomized controlled trials (RCTs) that reported functional capacity outcomes were included. The evidence was assessed using the GRADE approach.

RESULTS

Thirteen RCTs were included, involving 811 older adults living with AD. Multimodal exercise (ME), aerobic exercise (AE), and resistance exercise (RE) were used. The interventions were mainly supervised by caregivers. The evidence was low and with effect for activities of daily living (ADLs), moderate and with no effect for mobility and very low and with no effect for muscle strength, postural balance and flexibility after treatment with ME, moderate and with no effect for cardiorespiratory function and ADLs after treatment with AE. It was not possible to synthesize any type of evidence for RE.

CONCLUSIONS

Multimodal exercise promotes improvements in functional capacity (ADLs). Therefore, the practice of physical exercise can be recommended for older adults living with AD. The involvement of the caregiver in the physical exercises should also be considered, as it could enhance the benefits of exercise for these older adults.Implications for rehabilitationHealthcare providers with clinical knowledge regarding physical exercise should promote, prescribe and support the daily practice of physical exercises for older adults living with Alzheimer's disease (AD).The involvement of caregivers in home-based physical exercise programs should be considered, as it could enhance the benefits of such programs for these older adults.It is important to consider the degree of cognitive impairment in older adults living with AD when outlining goals for the improvement in functional capacity through physical exercise.Multimodal exercise involving aerobic training, postural balance, muscle strengthening, and flexibility is capable of promoting an improvement in functional capacity (activities of daily living) for these older adults.

Gait control by the frontal lobe

The frontal lobe is crucial and contributes to controlling truncal motion, postural responses, and maintaining equilibrium and locomotion. The rich repertoire of frontal gait disorders gives some indication of this complexity. For human walking, it is necessary to simultaneously achieve at least two tasks, such as maintaining a bipedal upright posture and locomotion. Particularly, postural control plays an extremely significant role in enabling the subject to maintain stable gait behaviors to adapt to the environment. To achieve these requirements, the frontal cortex (1) uses cognitive information from the parietal, temporal, and occipital cortices, (2) creates plans and programs of gait behaviors, and (3) acts on the brainstem and spinal cord, where the core posture-gait mechanisms exist. Moreover, the frontal cortex enables one to achieve a variety of gait patterns in response to environmental changes by switching gait patterns from automatic routine to intentionally controlled and learning the new paradigms of gait strategy via networks with the basal ganglia, cerebellum, and limbic structures. This chapter discusses the role of each area of the frontal cortex in behavioral control and attempts to explain how frontal lobe controls walking with special reference to postural control.

Tai Chi practice enables prefrontal cortex bilateral activation and gait performance prioritization during dual-task negotiating obstacle in older adults

BACKGROUND

With aging, the cognitive function of the prefrontal cortex (PFC) declined, postural control weakened, and fall risk increased. As a mind-body exercise, regular Tai Chi practice could improve postural control and effectively prevent falls; however, underlying brain mechanisms remained unclear, which were shed light on by analyzing the effect of Tai Chi on the PFC in older adults by means of functional near-infrared spectroscopy (fNIRS).

METHODS

36 healthy older adults without Tai Chi experience were divided randomly into Tai Chi group and Control group. The experiment was conducted four times per week for 16 weeks; 27 participants remained and completed the experiment. Negotiating obstacle task (NOT) and negotiating obstacle with cognitive task (NOCT) were performed pre- and post-intervention, and Brodmann area 10 (BA10) was detected using fNIRS for hemodynamic response. A three-dimensional motion capture system measured walking speed.

RESULTS

After intervention in the Tai Chi group under NOCT, the HbO2 concentration change value (ΔHbO2) in BA10 was significantly greater (right BA10: p = 0.002, left BA10: p = 0.001), walking speed was significantly faster (p = 0.040), and dual-task cost was significantly lower than pre-intervention (p = 0.047). ΔHbO2 in BA10 under NOCT was negatively correlated with dual-task cost (right BA10: r = -0.443, p = 0.021, left BA10: r = -0.448, p = 0.019). There were strong negative correlations between ΔHbO2 and ΔHbR under NOCT either pre-intervention (left PFC r = -0.841, p < 0.001; right PFC r = -0.795, p < 0.001) or post-intervention (left PFC r = -0.842, p < 0.001; right PFC r = -0.744, p < 0.001).

CONCLUSION

Tai Chi practice might increase the cognitive resources in older adults through the PFC bilateral activation to prioritize gait performance during negotiating obstacles under a dual-task condition.

Non-drug Therapies for Alzheimer's Disease: A Review

Alzheimer's disease (AD) is a debilitating disease leading to great social and economic burdens worldwide. During the past decades, increasing understanding of this disease enables dynamic trials for disease interventions. Unfortunately, at present, AD still remains uncurable, and therefore, developing intervention strategies for improving symptoms and slowing down the disease process becomes a practical focus in parallel with searching for a disease-modifying medication. The aim of this review is to summarize the outcomes of AD clinical trials of non-drug therapies published in the past decade, including cognitive-oriented interventions, physical exercise interventions, brain stimulation, as well as nutrition supplementations, to find out the most effective interventions in the category by looking through the primary and secondary outcomes. The outcomes of the trials could be varied with the interventional approaches, the tested cohorts, the settings of observing outcomes, and the duration of follow-ups, which are all discussed in this review. Hence, we hope to provide crucial information for application of these interventions in real-world settings and assist with optimization of clinical trial designs in this area.

Prevalence, risk factors and effectiveness of falls prevention interventions for adults living with Mild Cognitive Impairment in the community: A systematic review and meta-analysis

OBJECTIVES

To identify falls prevalence, falls risk factors and evaluate the effectiveness of falls prevention interventions for community-dwelling people with Mild Cognitive Impairment.

DATA SOURCES

Peer-reviewed articles (inception to 4 August 2022) from PubMed, CINAHL, PsycInfo, EMBASE, Scopus, SportDiscus and the Cochrane library.

REVIEW METHODS

All types of methodological approaches were considered. Inclusion criteria were community-dwelling; diagnosis of Mild Cognitive Impairment; aged 50+ years. Interventions needed to include falls prevention programs aiming to reduce falls and/or risk of falls. Outcomes of interest included number and/or rate of falls, falls prevalence and falls risk factors. For controlled trials, any control group was included. Quality assessment was completed using Cochrane's Risk of Bias Tool for randomized controlled trials and the Standard Quality Assessment Criteria for Evaluating Primary Research Papers from a Variety of Fields for all other studies. Where statistical data pooling was not possible, narrative synthesis was used to present data in tables and figures.

RESULTS

Forty-seven studies were included. Prevalence of falls was 43% when data were gathered prospectively for 12 months. Confirmed falls risk factors included slow gait, dual-tasking, postural control and non-amnesic Mild Cognitive Impairment. Few studies evaluated interventions to reduce falls. Six meta-analyses were conducted, no significant reduction in falls was found.

CONCLUSIONS

Until further high-quality, adequately powered studies are available to guide practice, best practice guidelines recommend balance training as a core component of falls prevention programs for older people generally, as well as people with Mild Cognitive Impairment.

Abnormal neural oscillations during gait and dual-task in Parkinson’s disease

Gait dysfunctions are debilitating motor symptoms of Parkinson’s disease (PD) and may result in frequent falling with health complications. The contribution of the motor-cognitive network to gait disturbance can be studied more thoroughly by challenging motor-cognitive dual-task gait performances. Gait is a complex motor task that requires an appropriate contribution from motor and cognitive networks, reflected in frequency modulations among several cortical and subcortical networks. Electrophysiological recordings by scalp electroencephalography and implanted deep brain stimulation (DBS) electrodes have unveiled modulations of specific oscillatory patterns in the cortical-subcortical circuits in PD. In this review, we summarize oscillatory contributions of the cortical, basal ganglia, mesencephalic locomotor, and cerebellar regions during gait and dual-task activities in PD. We detail the involvement of the cognitive network in dual-task settings and compare how abnormal oscillations in the specific frequency bands in the cortical and subcortical regions correlate with gait deficits in PD, particularly freezing of gait (FOG). We suggest that altered neural oscillations in different frequencies can cause derangements in broader brain networks, so neuromodulation and pharmacological therapies should be considered to normalize those network oscillations to improve challenged gait and dual-task motor functions in PD. Specifically, the theta and beta bands in premotor cortical areas, subthalamic nucleus, as well as alpha band activity in the brainstem prepontine nucleus, modulate under clinically effective levodopa and DBS therapies, improving gait and dual-task performance in PD with FOG, compared to PD without FOG and age-matched healthy control groups.

Phase-dependent Brain Activation of the Frontal and Parietal Regions During Walking After Stroke - An fNIRS Study

Background

Recovery of walking post-stroke is highly variable. Accurately measuring and documenting functional brain activation characteristics during walking can help guide rehabilitation. Previous work in this area has been limited to investigations of frontal brain regions and have not utilized recent technological and analytical advances for more accurate measurements. There were three aims for this study: to characterize the hemodynamic profile during walking post-stroke, to investigate regional changes in brain activation during different phases of walking, and to related brain changes to clinical measures.

Methods

Functional near-infrared spectroscopy (fNIRS) along the pre-frontal, premotor, sensorimotor, and posterior parietal cortices was used on twenty individuals greater than six months post-stroke. Individual fNIRS optodes were digitized and used to estimate channel locations on each participant and short separation channels were used to control for extracerebral hemodynamic changes. Participants walked at their comfortable pace several times along a hallway while brain activation was recorded. Exploratory cluster analysis was conducted to determine if there was a link between brain activation and clinical measures.

Results

Sustained activation was observed in the pre-frontal cortex with the ipsilesional hemisphere showing greater activation compared to the contralesional side. Sensorimotor cortex was active during the early, acceleration stage of walking only. Posterior parietal cortex showed changes in activation during the later, steady-state stage of walking. Faster gait speeds also related to increased activation in contralesional sensorimotor and posterior parietal cortices. Exploratory analysis clustered participants into two distinct groups based on their brain activation profiles and generally showed that individuals with greater activation tended to have better physical outcomes.

Conclusions

These findings can guide future research for obtaining adequate power and determining factors that can be used as effect modifiers to reduce inter-subject variability. Overall, this is the first study to report specific oxygenated and deoxygenated hemoglobin changes in frontal to parietal regions during walking in the stroke population. Our results shed light on the importance of measuring brain activation across the cortex and show the importance of pre-frontal, sensorimotor, and posterior parietal cortices in walking after a stroke.

Assessments of prolonged effects of desflurane and sevoflurane on motor learning deficits in aged AppNL-G-F/NL-G-F mice

As the proportion of elderly in society increases, so do the number of older patients undergoing surgical procedures. This is concerning as exposure to anesthesia has been identified as a risk factor for Alzheimer's disease (AD). However, the causal relationship between clinical AD development and anesthesia remains conjectural. Preclinical studies have demonstrated that anesthesia, such as halothane, isoflurane, and sevoflurane, induces AD-like pathophysiological changes and cognitive impairments in transgenic mouse models of AD. Desflurane does not have these effects and is expected to have more potential for use in elderly patients, yet little is known about its effects, especially on non-cognitive functions, such as motor and emotional functions. Thus, we examined the postanesthetic effects of desflurane and sevoflurane on motor and emotional function in aged App^{NL-G-F/NL-G-F} (App-KI) mice. This is a recently developed transgenic mouse model of AD exhibiting amyloid β peptide (Aβ) amyloidosis and a neuroinflammatory response in an age-dependent manner without non-physiological amyloid precursor protein (APP) overexpression. Mice were subjected to a short behavioral test battery consisting of an elevated plus maze, a balance beam test, and a tail suspension test seven days after exposure to 8.0% desflurane for 6 h or 2.8% sevoflurane for 2 h. App-KI mice showed significant increments in the percentage of entry and time spent in open arms in the elevated plus maze, increments in the number of slips and latency to traverse for the balance beam test, increments in the limb clasping score, increments in immobile duration, and decrements in latency to first immobile episode for the tail suspension test compared to age-matched wild type (WT) controls. Desflurane- and sevoflurane-exposed App-KI mice showed a delayed decrement in the number of slips for each trial in the balance beam test, while air-treated App-KI mice rapidly improved their performance, and increased their clasping behavior in the tail suspension test. Furthermore, App-KI inhibited the change in membrane GluA3 following exposure to anesthetics in the cerebellum. These results suggest high validity of App-KI mice as an animal model of AD.

Correlation between changes in Timed Up and Go performance and cognition in older people with mild cognitive impairment: A longitudinal study

BACKGROUND

Compare changes in performance on subtasks of the Timed Up and Go test over 32 months in older adults with and without mild cognitive impairment; analyze the correlation between frontal cognitive functions at baseline and changes in Timed Up and Go subtasks over time.

METHODS

A longitudinal study was conducted involving 31 older adults (15 with and 16 without cognitive impairment). Functional mobility was assessed at both evaluations using an adapted version of the Timed Up and Go test and the Qualisys motion system. The test was divided into five subtasks: sit-to-stand, walking forward, turn-to-walk, walking back and turn-to-sit. Cognition was assessed at baseline using the Frontal Assessment Battery and the Clock Drawing Test.

FINDINGS

Significant differences in changes in the sit-to-stand subtask over time were found between groups. The difference in the time required to conclude this subtask was greater in the older adults with cognitive impairment. However, the difference in kinematic variables (peak trunk speed and range of motion) was greater in the group without cognitive impairment. Strong and moderate correlations were found between frontal cognitive functions and changes in Timed Up and Go subtasks, especially those involving transitions (sit-to-stand, turn-to-walk and turn-to-sit) in both groups.

INTERPRETATION

Motor intervention protocols should incorporate the sit-to-stand subtask in older adults with mild cognitive impairment. Moreover, changes in more complex subtasks seem to be related to frontal cognitive performance at baseline. Therefore, treatments that combine motor and cognitive functions should be administered to older adults regardless of cognitive impairment.

Cognitive ability and motor performances in the elderly

Background/Aim. Aging entails a wide range of cognitive processes that are not independent of one another. It leads to changes in physical-motor characteristics and sometimes to disability. The aim of this study was to examine the association between multiple cognitive performances in elderly subjects and their physical-motor abilities. Method. The study included 98 elderly participants (60+) (16 males and 82 females). Cognitive abilities were assessed by the Montreal Cognitive Assessment (MoCA)/Serbian version, and physical measures were assessed by the Senior Fitness Test with its five subtests, supplemented by the Walking Speed Test. Results. Several MoCA items demonstrated relatively low variability, i.e., they proved to be too easy for most of the participants. The participants exhibited the lowest performance on the memory relating to other domains, followed by executive functions, visuospatial skills, attention, concentration, and working memory domains, with the highest performance on temporal and spatial orientation relating to other domains. Executive functions and language correlated most significantly with physical strength. Agility and dynamic balance, lower- and upper-body strength, and aerobic endurance correlated moderately and positively. Conclusion. This study underlines the positive correlation between physical fitness and cognitive level in the elderly and emphasizes the importance of physical fitness for cognitive functions, especially those of executive type in elderly subjects. Clinicians should consider the association between cognitive function and physical-motor performances when dealing with functioning improvement in the elderly. The importance of designing the most efficient exercise pro-grams to achieve maximal somatic and cognitive effects is emphasized.

Neural markers of proactive and reactive cognitive control are altered during walking: A Mobile Brain-Body Imaging (MoBI) study

The processing of sensory information and the generation of motor commands needed to produce coordinated actions can interfere with ongoing cognitive tasks. Even simple motor behaviors like walking can alter cognitive task performance. This cognitive-motor interference (CMI) could arise from disruption of planning in anticipation of carrying out the task (proactive control) and/or from disruption of the execution of the task (reactive control). In young healthy adults, walking-induced interference with behavioral performance may not be readily observable because flexibility in neural circuits can compensate for the added demands of simultaneous loads. In this study, cognitive-motor loads were systematically increased during cued task-switching while underlying neurophysiologic changes in proactive and reactive mechanisms were measured. Brain activity was recorded from 22 healthy young adults using 64-channel electroencephalography (EEG) based Mobile Brain/Body Imaging (MoBI) as they alternately sat or walked during performance of cued task-switching. Walking altered neurophysiological indices of both proactive and reactive control. Walking amplified cue-evoked late fontal slow waves, and reduced the amplitude of target-evoked fronto-central N2 and parietal P3. The effects of walking on evoked neural responses systematically increased as the task became increasingly difficult. This may provide an objective brain marker of increasing cognitive load, and may prove to be useful in identifying seemingly healthy individuals who are currently able to disguise ongoing degenerative processes through active compensation. If, however, degeneration continues unabated these people may reach a compensatory limit at which point both cognitive performance and control of coordinated actions may decline rapidly.

Effect of Heart Rate Reserve on Prefrontal Cortical Activation While Dual-Task Walking in Older Adults

Hypertension is considered a risk factor for cardiovascular health and non-amnestic cognitive impairment in older adults. While heart rate reserve (HRR) has been shown to be a risk factor for hypertension, how impaired HRR in older adults can lead to cognitive impairment is still unclear. The objective of this study was to examine the effects of HRR on prefrontal cortical (PFC) activation under varying dual-task demands in older adults. Twenty-eight older adults (50-82 years of age) were included in this study and divided into higher (n = 14) and lower (n = 14) HRR groups. Participants engaged in the cognitive task which was the Modified Stroop Color Word Test (MSCWT) on a self-paced treadmill while walking. Participants with higher HRR demonstrated increased PFC activation in comparison to lower HRR, even after controlling for covariates in analysis. Furthermore, as cognitive task difficulty increased (from neutral to congruent to incongruent to switching), PFC activation increased. In addition, there was a significant interaction between tasks and HRR group, with older adults with higher HRR demonstrating increases in PFC activation, faster gait speed, and increased accuracy, relative to those with lower HRR, when going from neutral to switching tasks. These results provide evidence of a relationship between HRR and prefrontal cortical activation and cognitive and physical performance, suggesting that HRR may serve as a biomarker for cognitive health of an older adult with or without cardiovascular risk.

The Performance of Dual-Task Tests Can Be a Combined Neuro-Psychological and Motor Marker of Mild Cognitive Impairment, Depression and Dementia in Geriatric Patients-A Cross-Sectional Study

The study aims to assess the performance of dual-task tests in the geriatric population and their association with the cognitive status of the patients.

METHODS

Patients admitted to the Department of Geriatrics, Hospital of the Ministry of Interior and Administration on Bialystok, Poland, in 2019 and 2020 were enrolled in the study. Data on the patients' clinical, functional, and cognitive status were collected based on the comprehensive geriatric assessment. Dual-task tests included Timed Up and Go (TUG) test while counting backward (CB7), enumerating animals (EA), and holding a cup (TUG M).

RESULTS

250 patients were included in the study, with a median age of 81.5 years (IQR 76-86) and most above 75 years of age (80.8%). Only 29 (11.6%) of study participants had no cognitive or mood disorders. Depression was diagnosed in 30.4%, MCI in 12%, and dementia in 38.4% of cases with median Mini-Mental Score Evaluation (MMSE) 17 (12-20) points. Dual-task TUG CB7 results did not differ between cognitive conditions of patients. TUG EA differed between healthy controls and other cognitive groups and TUG between healthy controls and depression and dementia, but not mild cognitive impairment (MCI). The performance of all dual-task tests differed in patients with and without dementia. Ability to finish TUG CB7 was low even in the group without dementia. There were statistically significant differences in median scores of MMSE and Clock Drawing Test (CDT) between patients who were able or not to finish single and dual-task gait tests.

CONCLUSION

Dual-task test results and the performance of these tasks can differentiate patients with depression, MCI and dementia compared to healthy controls in the geriatric population.

Single-Task or Dual-Task? Gait Assessment as a Potential Diagnostic Tool for Alzheimer's Dementia

Background:

A person’s gait performance requires the integration of sensorimotor and cognitive systems. Therefore, a person’s gait may be influenced by concurrent cognitive load such as simultaneous talking. Although it has been known that gait performance of people with Alzheimer’s dementia (AD) is compromised when they attempt a dual-task walking task, it is unclear if using a dual-task gait performance during an AD assessment yields higher diagnostic accuracy.

Objective:

This study was designed to compare the predictive power for AD of dual-task gait performance in an AD assessment to that of single-task gait performance.

Methods:

Participants (14 with AD and 15 healthy controls) walked across the GAITRite© Portable Walkway mat under three different cognitive load conditions: no simultaneous cognitive load, walking while counting numbers by ones, and walking while completing category naming.

Results:

Multiple logistic regression revealed that the gait performance under a dual-task condition (i.e., concurrent counting or category naming) increased the proportion of variance explained by the FAP, SL, and DST, of the incidence of AD.

Conclusion:

Dual-task walking and talking may be a more effective diagnostic feature than single-task walking in a comprehensive AD diagnostic assessment.

Falls: a marker of preclinical Alzheimer disease: a cohort study protocol

INTRODUCTION

Progression to symptomatic Alzheimer disease (AD) occurs slowly over a series of preclinical stages. Declining functional mobility may be an early indicator of loss of brain network integration and may lead to an increased risk of experiencing falls. It is unknown whether measures of functional mobility and falls are preclinical markers of AD. The purpose of this study is to examine (1) the relationship between falls and functional mobility with AD biomarkers to determine when falls occur within the temporal progression to symptomatic Alzheimer disease, and (2) the attentional compared with perceptual/motor systems that underlie falls and functional mobility changes seen with AD.

METHODS AND ANALYSIS

This longitudinal cohort study will be conducted at the Knight Alzheimer Disease Research Center. Approximately 350 cognitively normal participants (with and without preclinical AD) will complete an in-home visit every year for 4 years. During each yearly assessment, functional mobility will be assessed using the Performance Oriented Mobility Assessment, Timed Up and Go, and Timed Up and Go dual task. Data regarding falls (including number and severity) will be collected monthly by self-report and confirmed through interviews. This study will leverage ongoing neuropsychological assessments and neuroimaging (including molecular imaging using positron emission tomography and MRI) performed by the Knight Alzheimer Disease Research Center. Relationships between falls and biomarkers of amyloid, tau and neurodegeneration will be evaluated.

ETHICS AND DISSEMINATION

This study was approved by the Washington University in St. Louis Institutional Review Board (reference number 201807135). Written informed consent will be obtained in the home prior to the collection of any study data. Results will be published in peer-reviewed publications and presented at national and international conferences.

TRIAL REGISTRATION NUMBER

NCT04949529; Pre-results.

Critical spatiotemporal gait parameters for individuals with dementia: A systematic review and meta-analysis

Instrumented gait analysis allows for the identification of walking parameters to predict cognitive decline and the worsening of dementia. The aim of this study was to perform a meta-analysis to better clarify which gait parameters are affected or modified with the progression of the dementia in a larger sample, as well as which gait assessment conditions (single-task or dual-task conditions) would be more sensitive to reflect the influence of dementia. Literature searches were conducted with the keywords "quantitative gait" OR "gait analysis" AND "dementia" AND "single-task" AND "dual-task," and for "quantitative gait" OR "gait analysis" AND "dementia" AND "fall risk" on PubMed, EMBASE, the Cochrane Library, Scopus, and Web of Science. The results were used to perform a systematic review focussing on instrumental quantitative assessment of the walking of patients with dementia, during both single and dual tasks. The search was performed independently by two authors (C. R. and C. M.) from January 2018 to April 2020 using the PICOS criteria. Nine publications met the inclusion criteria and were included in the systematic review. Our meta-analysis showed that during a single task, most of the spatiotemporal parameters of gait discriminated best between patients with dementia and healthy controls, including speed, cadence, stride length, stride time, stride time variability, and stance time. In dual tasks, only speed, stride length, and stride time variability discriminated between the two groups. In addition, compared with spatial parameters (e.g. stride length), some temporal gait parameters were more correlated to the risk of falls during the comfortable walking in a single task, such as cadence, stride time, stride time variability, and stance time. During a dual task, only the variability of stride time was associated with the risk of falls.

The influence of cognitive load on balance control during steady-state walking

For an individual to successfully walk, they must maintain control of their dynamic balance. However, situations that require increased cognitive attention may impair an individual's ability to actively control their balance. While dual-task studies have analyzed walking-while-talking conditions, few studies have focused specifically on the influence of cognitive load on balance control. The purpose of this study was to assess how individuals prioritize their cognitive resources and control dynamic balance during dual-task conditions of varying difficulty. Young healthy adults (n = 15) performed two single-task conditions (spelling-while-standing and treadmill walking with no cognitive load) and three dual-task conditions (treadmill walking with increasing cognitive load: attentive listening and spelling short and long words backwards). Cognitive performance did not change between the single- and dual-task as measured by spelling percent error and response rate (p = 0.300). Balance control, assessed using the range of whole-body angular momentum, did not change between the no load and listening conditions, but decreased during the short and long spelling conditions (p < 0.001). These results highlight that in young adults balance control decreases during dual-task treadmill walking with increased cognitive loads, but their cognitive performance does not change. The decrease in balance control suggests that participants prioritized cognitive performance over balance control during these dual-task walking conditions. This work offers additional insight into the automaticity of walking and task-prioritization in healthy young individuals and provides the basis for future studies to determine differences in neurologically impaired populations.

Effects of acute exercise at different intensities on fine motor-cognitive dual-task performance while walking: A functional near-infrared spectroscopy study

Studies on the effects of acute exercises on cognitive functions vary greatly and depend on the duration and intensity of exercise and the type of cognitive tasks. This study aimed to investigate the neural correlates that underpin the acute effects of high-intensity interval (HIIE) versus moderate-intensity continuous exercise (MCE) on fine motor-cognitive performance while walking (dual-task, DT) in healthy young adults. Twenty-nine healthy right-handers (mean age: 25.1 years ± 4.04; 7 female) performed the digital trail-making-test (dTMT) while walking (5 km/h) before and after acute exercise. During task performance, the hemodynamic activation of the frontopolar area (FPA), dorsolateral prefrontal (DLPFC), and motor cortex (M1) was recorded using functional near-infrared spectroscopy (fNIRS). Both HIIE and MCE resulted in improved dTMT performance, as reflected by an increase in the number of completed circles and a reduction in the time within and between circuits (reflecting improvements in working memory, inhibition, and decision making). Notably, HIIE evoked higher cortical activity on all brain areas measured in the present study than the MCE group. To our knowledge, these results provide the first empirical evidence using a mobile neuroimaging approach that both HIIE and MCE improve executive function during walking, likely mediated by increased activation of the task-related area of the prefrontal cortex and the ability to effectively use, among other things, high fitness levels as neural enrichment resources.

Progression of Gait Changes in Older Adults With Mild Cognitive Impairment: A Systematic Review

BACKGROUND AND PURPOSE

The identification of altered gait and its progression over time is important to gaining a better understanding of the clinical aspects of mild cognitive impairment (MCI) in older adults. The aim of the present systematic review was to determine changes in gait variables over time among older adults with MCI.

METHODS

The PubMed, Web of Science, Scopus, and Science Direct databases were searched for relevant articles using the following keywords and Medical Subject Headings: Aged AND "Mild cognitive impairment" AND (gait OR locomotion). A hand search was also performed of the reference lists of the selected articles in an attempt to find additional records. The following were the inclusion criteria: longitudinal studies and clinical trials involving a control group without intervention; samples of individuals 65 years or older; and characterization of gait using a single or dual task.

RESULTS AND DISCUSSION

The initial search led to the retrieval of 6979 studies, 9 of which met the inclusion criteria. The duration of follow-up among the studies ranged from 6 months to 2 years. Most trials investigated gait speed. Other gait variables were step length, time required to walk a given distance, and mean weekly gait speed. Altered gait progressed in older adults with MCI. The main alterations were gait speed and variability in daily number of steps in follow-up periods lasting more than 1 year. No significant changes in gait variables were found in shorter follow-up periods (up to 6 months).

CONCLUSIONS

The progression of gait changes in older adults with MCI has been underinvestigated. MCI leads to reduced gait speed in longer follow-up periods. Such information can contribute to the determination of motor interventions for older adults with MCI, especially in the early stages.

Fall-related cognition, motor function, functional ability, and depression measures in older adults with dementia

BACKGROUND

As the severity of dementia progresses over time, cognition and motor functions such as muscle strength, balance, and gait are disturbed, and they eventually increase the risk of fall in patients with dementia.

OBJECTIVE

To determine the relationship between the fall risk and cognition, motor function, functional ability, and depression in older adults with dementia.

METHODS

Seventy-four older adults diagnosed with dementia were recruited. Clinical measurements included the Fall Risk Scale by Huh (FSH), Korean version of the Mini-Mental State Examination (MMSE-K), hand grip strength (HGS), Tinetti Performance Oriented Mobility Assessment (POMA), 10-m walk test (10-MWT), Korean version of the Modified Barthel Index (MBI-K), and the Geriatric Depression Scale (GDS).

RESUTLS

The MMSE-K was significantly correlated with the FSH, HGS, and the MBI-K, and FSH was significantly correlated with all of the other outcome measures. In particular, the MMSE-K, HGS, POMA, and the MBI-K were negatively correlated with fall history among the FHS sub-items. Additionally, the MMSE sub-item, attention/concentration was associated with the FSH, HGS, POMA, and the MBI-K.

CONCLUSIONS

These findings suggest that falling is significantly related to impaired cognition, reduced muscle strength, impaired balance, gait, and activities of daily living abilities, and depression in older adults with dementia.

Dual-Task Gait Assessment in a Clinical Sample: Implications for Improved Detection of Mild Cognitive Impairment

OBJECTIVES

Research has longitudinally linked dual-task gait dysfunction to mild cognitive impairment (MCI) and dementia risk. Our group previously demonstrated that dual-task gait speed assessment distinguished between subjective cognitive complaints (SCC) and MCI in a memory clinic setting, and also found that differences in dual-task gait speed were largely attributable to executive attention processes. This study aimed to reproduce these findings in a larger diverse sample and to extend them by examining whether there were group differences in single- versus dual-task cognitive performance (number of letters correctly sequenced backward).

METHOD

Two-hundred fifty-two patients (M age = 66.01 years, SD = 10.46; 119 MCI, 133 SCC) presenting with cognitive complaints in an academic medical setting underwent comprehensive neuropsychological and gait assessment (single- and dual-task conditions).

RESULTS

Patients with MCI walked slower and showed greater decrement in cognitive performance than those with SCC during dual-task conditions. Neuropsychological measures of executive attention accounted for significant variance in dual-task gait performance across diagnostic groups beyond demographic and health risk factors.

DISCUSSION

Reproduction of our results within a sample over four times the previous size provides support for the use of dual-task gait assessment as a marker of MCI risk in clinical settings.

Rivastigmine improves dual-task gait velocity in patients with Alzheimer's disease

Background

Gait impairments are common in patients with Alzheimer’s disease. Cholinesterase inhibitors are used to treat the symptoms of patients with Alzheimer’s disease, but they have not been shown to reduce the severity of Alzheimer’s disease-related gait disorders.

Methods

This was a prospective, single-arm, open-label, non-randomized study. The aim of the present study was to determine the effect of the acetylcholinesterase inhibitor rivastigmine on gait in 21 newly diagnosed patients with mild to moderate Alzheimer’s disease. The outcome variables were velocity, stride length, and cadence during single-task and dual-task gait trials. The subjects were also assessed with the Mini-Mental State Examination, Alzheimer’s Disease Cooperative Study Activities of Daily Living, Functional Assessment Staging, and Geriatric Depression Scale.

Results

After 12 weeks of treatment with rivastigmine, gait velocity was significantly improved in the dual-task gait trials; gait velocity was increased from 40.59 ± 13.59 m/min at baseline to 46.88 ± 12.73 m/min when counting backward from 100 in steps of 7 while walking, and gait velocity was increased from 37.06 ± 15.57 m/min at baseline to 42.03 ± 14.02 m/min when naming animals while walking. In the single-task gait trials, which consisted only of walking at their usual pace or at a fast pace, gait velocity was not increased by rivastigmine administration.

Conclusion

Our findings indicated that rivastigmine improved gait in subjects with mild to moderate Alzheimer’s disease during dual-task trials. The observed enhancement of dual-task gait might be caused by an improvement of cognitive function rather than motor function.

Trial registration

UMIN, UMIN000025869. Registered December 16, 2016, https://upload.umin.ac.jp/cgi-open-bin/icdr/ctr_view.cgi?recptno=R000029744

Effects of dual task on gait velocity and cadence in cerebral palsied children with spastic hemiparesis or diparesis

Gait is generally considered an automated process with little or no cognitive input. In most individuals with Cerebral Palsy (CP), walking restrictions may accompany during childhood and adolescence. The aim of this study was to determine the effects of dual task on Gait Velocity (GV) and Cadence (C) in Cerebral Palsied Children with Spastic Hemiparesis or Diparesis (CPCSHD). Fourteen boys, seven girls' spastic hemiparesis children (mean age: 13.33 ± 3.79 years) and twelve girls, nine boys' diparesis children (mean age: 14.44 ± 3.24 years) were included in the study. Forty-two CPCSHD having level 1 or 2 according to the Gross Motor Function Classification System (GMFCS) were included in this comparative study. GV was calculated using a chronometer for a 10-m walk on the ground with shoes. Cadence was calculated accounting the number of steps during 1-min walk. Both GV and C tests were performed by each participant with single task first. After the single task, all were asked to perform the dual task carrying a plastic water-filled bottle. There were no significant differences between the hemiparesis and diparesis in terms of demographics data. When children with hemiparesis and diparesis compare each other, no significant differences were found in terms of all the outcome parameters. The results obtained from this study indicate that walking speed and cadence decrease during a dual motor task in CPCSHD (p > 0.05). When hemiparesis and diparesis groups were compared, no difference was found between the groups.

Executive Function in High-Functioning Autism Spectrum Disorder: A Meta-analysis of fMRI Studies

Abnormalities in executive function (EF) are clinical markers for autism spectrum disorder (ASD). However, the neural mechanisms underlying abnormal EF in ASD remain unclear. This meta-analysis investigated the construct, abnormalities, and age-related changes of EF in ASD. Thirty-three fMRI studies of inhibition, updating, and switching in individuals with high-functioning ASD were included (n = 1114; age range 7-57 years). The results revealed that the EF construct in ASD could be unitary (i.e., common EF) in children/adolescents, but unitary and diverse (i.e., common EF and inhibition) in adults. Abnormalities in this EF construct were found across development in individuals with ASD in comparison with typically developing individuals. Implications and recommendations are discussed for EF theory and for practice in ASD.

Associations of Dual Task Exergaming with Cognitive-Motor Interference in Older Adults with Mild Cognitive Impairment: A Single-Arm Pilot Study

Purpose

To examine the feasibility and effectiveness of dual task (DT) exergaming to improve volitional balance control in older adults with mild cognitive impairment (MCI).

Methods

Ten older adults with MCI were examined at baseline (week-0) and post-training (week-5) on volitional balance control (maximum excursion of center of gravity, MXE [%]) while performing cognitive task (auditory clock test or letter number sequencing task) and on the NIH-motor and cognitive toolboxes. DT exergaming training lasted for 12 sessions which consisted of performing explicit cognitive tasks while playing the Wii-Fit balance games.

Results

From pre- to post-training, MXE improved (p<0.05); however, cognitive accuracy (cognitive task) remained the same (p>0.05). Improvement in NIH motor and cognitive toolbox tests was observed post-training (p<0.05).

Conclusion

DT exergaming was associated to improvements in balance control under attention-demanding conditions in MCI. Future studies may focus on examining the efficacy of such training.

A Comparison of Cardiopulmonary Exercise Testing and Field Walking Tests in Community-Dwelling Older Adults With Mild-to-Moderate Alzheimer's Dementia

The purpose of this study was to investigate the relationships among peak exercise parameters on 6-min walk test, shuttle walk test, and laboratory-based cardiopulmonary exercise testing in persons with Alzheimer's dementia. This study is a cross-sectional analysis of the baseline data of 90 participants (age 77.1 [6.6] years, 43% female) from the FIT-AD trial. Cardiopulmonary exercise testing produced significantly higher peak heart rate (118.6 [17.5] vs. 106 [22.8] vs. 106 [18.8] beats/min), rating of perceived exertion (16 [2.1] vs. 12 [2.3] vs. 11 [2.1]), and systolic blood pressure (182 [23.7] vs. 156 [18.9] vs. 150 [16.9] mmHg) compared with the shuttle walk test and 6-min walk test, respectively. Peak walking distance on shuttle walk test (241.3 [127.3] m) and 6-min walk test (365.0 [107.9] m) significantly correlated with peak oxygen consumption (17.1 [4.3] ml·kg-1·min-1) on cardiopulmonary exercise testing (r = .449, p ≤ .001 and r = .435, p ≤ .001), respectively, which is considerably lower than what is seen in older adults and persons with cardiopulmonary diseases.

Center of pressure displacement characteristics differentiate fall risk in older people: A systematic review with meta-analysis

Falling is the second most prevalent cause of accidental death in the world. Currently available clinical tests to assess balance in older people are insufficiently sensitive to screen for fall risk in this population. Laboratory tests that record the center of pressure (COP) trajectory could overcome this problem but despite their widespread use, the choice of COP trajectory features for use as a biomarker of fall risk lacks consensus. This systematic review and meta-analysis aimed at identifying the best COP characteristics to predict risk of falling in older adults. More than 4000 articles were screened; 44 (7176 older adults) were included in this study. Several COP parameters emerged as good indices to discriminate fallers from non-fallers. From sensitivity analysis, Sway area per unit time, anteroposterior mean velocity, and radial mean velocity were the best traditional features. In this study, identification of older people with a high fall risk was demonstrated using quiet-standing recordings. Such screening would also be useful for routine follow-up of balance changes in older fallers in clinical practice.

Feasibility of dual-task gait to estimate Alzheimer's related cognitive decline in Down syndrome

INTRODUCTION

The striatum and frontal lobes have been shown to have early Alzheimer's disease (AD) neuropathology and are critical for motor and cognitive function. We hypothesized gait would be associated with early-stage dementia in Down syndrome (DS), a cohort at risk for AD.

METHODS

Twenty-eight participants with DS were enrolled in the study. Participants walked at their self-selected pace and while completing a dual task (counting, obstacle, or counting+obstacle).

RESULTS

All participants were able to complete the self-paced condition and 78.57-96.42% completed the dual-task conditions. There was a trend for greater dual-task effects on gait velocity based on dementia diagnosis. Gait velocity had stronger associations with clinical dementia assessments than age or diagnosis.

DISCUSSION

A dual-task gait paradigm is feasible to conduct with adults with DS and is associated with age and cognitive impairment. Dual-task gait may serve as an indicator of early stage dementia in DS.

Distinct Effects of Motor Training on Resting-State Functional Networks of the Brain in Parkinson’s Disease

Background. Nigrostriatal dopaminergic loss is a hallmark of Parkinson’s disease (PD) pathophysiology, leading to motor Parkinsonism. Different intervention protocols have shown that motor and cognitive functions improvement in PD occur via the modulation of distinct motor and cognitive pathways. Objective. To investigate the effects of two motor training programs on the brains’ functional networks in PD patients. Methods. Thirty-seven PD patients were prospectively studied. All enrolled patients underwent either treadmill training (TT) (n = 19) or treadmill with virtual reality (TT + VR) (n = 18) for 6 weeks. Magnetic resonance imaging (MRI) scans (3 T) acquiring 3-dimensional T1-weighted and resting-state functional MRI (rs-fMRI) data sets were performed at baseline and after 6 weeks. Independent component analysis (ICA) was conducted, and functional connectivity (FC) changes within large-scale functional brain networks were examined. Results. In both groups, significant post-training FC decrease in striatal, limbic, and parietal regions within the basal ganglia network, executive control network, and frontal-striatal network, and significant FC increase in the caudate, and cingulate within the sensorimotor network (SMN) were observed. Moreover, a significant time × group interaction was detected where TT + VR training had greater effects on FC levels in the supplementary motor area (SMA) and right precentral gyrus within the SMN, and in the right middle frontal gyrus (MFG) within the cerebellar network. These FC alterations were associated with improved usual and dual-task walking performance. Conclusions. These results suggest that TT with-and-without the addition of a VR component affects distinct neural pathways, highlighting the potential for beneficial neural plasticity in PD. Such distinctive task-specific pathways may foster the facilitation of interventions tailored to the individual needs of PD patients. Registered at Clinicaltrials.gov number: NCT01732653.

Differential Effects of Concurrent Tasks on Gait in Typically Developing Children: A Meta-Analysis

The objective of this study was to systematically analyze the literature surrounding dual-task (DT) effects on gait in typically developing children (TDC) and to conduct meta-analyses where applicable. After reviewing the abstracts of 676 articles, a total of 22 studies were included. The outcomes of interest were relative change in gait speed, cadence, stride length, double support time, variability in stride length between single and DT walking; and the exposures were concurrent tasks used for DT gait assessment. DT significantly affected each gait parameter (point estimate (PE), ranged from PE, -0.10; 95% CI, -0.13 to -0.08; p < .001 to PE, -0.66; 95% CI, -0.94 to -0.38; p < .001). The strength of DT effects varied by the concurrent task used. The greatest DT effect on gait speed, which was the most commonly presented outcome, was reported when upper extremity complex functional tasks (PE, -0.36; 95% CI, -0.49 to -0.23; p < .001, fine motor tasks (PE, -0.35; 95% CI, -0.38 to -0.32; p < .001), and verbal fluency tasks (PE, -0.26; 95% CI, -0.30 to -0.21; p < .001) were completed concurrently with gait. Children and adolescents experience performance decrements when they walk under DT conditions. Concurrent tasks differentially affect the degree of DT interference for each gait parameter.

Effects of a 16-week multimodal exercise program on gait performance in individuals with dementia: a multicenter randomized controlled trial

Background

There is a high prevalence of gait impairments in individuals with dementia (IWD). Gait impairments are associated with increased risk of falls, disability, and economic burden for health care systems. Only few studies have investigated the effectiveness of physical activity on gait performance in IWD, reporting promising but inconsistent results. Thus, this study aimed to investigate the effectiveness of a multimodal exercise program (MEP) on gait performance in IWD.

Methods

In this parallel-group randomized controlled trial, we enrolled 319 IWD of mild to moderate severity, living in care facilities, aged ≥ 65 years, and being able to walk at least 10 m. The control group (n = 118) received conventional treatment, whereas the intervention group (n = 201) additionally participated in a 16-week MEP specifically tailored to IWD. We examined the effects of the MEP on spatiotemporal gait parameters and dual task costs by using the gait analysis system GAITRite. Additionally, we compared characteristics between positive, non-, and negative responders, and investigated the impact of changes in underlying motor and cognitive performance in the intervention group by conducting multiple regression analyses.

Results

Two-factor analyses of variance with repeated measurements did not reveal any statistically significant time*group effects on either spatiotemporal gait parameters or dual task costs. Differences in baseline gait performance, mobility, lower limb strength, and severity of cognitive impairments were observed between positive, non-, and negative responders. Positive responders were characterized by lower motor performance compared to negative and non-responders, while non-responders showed better cognitive performance than negative responders. Changes in lower limb strength and function, mobility, executive function, attention, and working memory explained up to 39.4% of the variance of changes in gait performance.

Conclusions

The effectiveness of a standardized MEP on gait performance in IWD was limited, probably due to insufficient intensity and amount of specific walking tasks as well as the large heterogeneity of the sample. However, additional analyses revealed prerequisites of individual characteristics and impacts of changes in underlying motor and cognitive performance. Considering such factors may improve the effectiveness of a physical activity intervention among IWD.

Trial registration

DRKS00010538 (German Clinical Trial Register, date of registration: 01 June 2016, retrospectively registered, https://www.drks.de/drks_web/setLocale_EN.do).

SMR/Theta Neurofeedback Training Improves Cognitive Performance and EEG Activity in Elderly With Mild Cognitive Impairment: A Pilot Study

Background: Neurofeedback (NF) training, as a method of self-regulation of brain activity, may be beneficial in elderly patients with mild cognitive impairment (MCI). In this pilot study, we investigated whether a sensorimotor (SMR)/theta NF training could improve cognitive performance and brain electrical activity in elderly patients with MCI. Methods: Twenty elderly patients with MCI were assigned to 20 consecutive sessions of sensorimotor (SMR)/theta NF training, during 10 weeks, on a basis of two sessions each week. Neuropsychological assessments and questionnaires, as well as electroencephalogram (EEG), were performed and compared between baseline (T0), after the last NF training session at 10 weeks (T1), and 1-month follow-up (T2). Results: Repeated measures ANOVA revealed that from baseline to post-intervention, participants showed significant improvement in the Montreal cognitive assessment (MoCa, F = 4.78; p = 0.012), the delayed recall of the Rey auditory verbal learning test (RAVLT, F = 3.675; p = 0.032), the Forward digit span (F = 13.82; p < 0.0001), the Anxiety Goldberg Scale (F = 4.54; p = 0.015), the Wechsler Adult Intelligence Score-Fourth Edition (WAIS-IV; F = 24.75; p < 0.0001), and the Mac Nair score (F = 4.47; p = 0.016). EEG theta power (F = 4.44; p = 0.016) and alpha power (F = 3.84; p = 0.027) during eyes-closed resting-state significantly increased after the NF training and showed sustained improvement at a 1-month follow-up. Conclusion: Our results suggest that NF training could be effective to reduce cognitive deficits in elderly patients with MCI and improve their EEG activity. If these findings are confirmed by randomized controlled studies with larger samples of patients, NF could be seen as a useful non-invasive, non-pharmacological tool for preventing further decline, rehabilitation of cognitive function in the elderly. Clinical Trial Registration: This pilot study was a preliminary step before the trial registered in www.ClinicalTrials.gov, under the number of NCT03526692.

Brain volumes and dual-task performance correlates among individuals with cognitive impairment: a retrospective analysis

Cognitive impairment (CI) is a prevalent condition characterized by loss of brain volume and changes in cognition, motor function, and dual-tasking ability. To examine associations between brain volumes, dual-task performance, and gait and balance in those with CI to elucidate the mechanisms underlying loss of function. We performed a retrospective analysis of medical records of patients with CI and compared brain volumes, dual-task performance, and measures of gait and balance. Greater cognitive and combined dual-task effects (DTE) are associated with smaller brain volumes. In contrast, motor DTE is not associated with distinct pattern of brain volumes. As brain volumes decrease, dual-task performance becomes more motor prioritized. Cognitive DTE is more strongly associated with decreased performance on measures of gait and balance than motor DTE. Decreased gait and balance performance are also associated with increased motor task prioritization. Cognitive DTE appears to be more strongly associated with decreased automaticity and gait and balance ability than motor DTE and should be utilized as a clinical and research outcome measure in this population. The increased motor task prioritization associated with decreased brain volume and function indicates a potential for accommodative strategies to maximize function in those with CI. Counterintuitive correlations between motor brain volumes and motor DTE in our study suggest a complicated interaction between brain pathology and function.