Motoric cognitive risk syndrome and incident dementia: results from a population-based prospective and observational cohort study.

BACKGROUND AND PURPOSE: Motoric cognitive risk syndrome (MCR), which is the juncture of subjective cognitive complaint and slow gait speed, is a pre-dementia stage. The aims of the study are (i) to compare characteristics between individuals who have MCR defined using slow walking speed and/or increased five-times-sit-to-stand (FTSS) time as its motor component(s); and (ii) to characterize the association of MCR and its various motor components with incident dementia including Alzheimer disease and non-Alzheimer dementia in the participants of the Epidémiologie de l'Ostéoporose (EPIDOS) study. METHODS: This prospective and observational cohort study selected 651 participants recruited from the EPIDOS study in Toulouse (France). MCR was defined as the association of subjective cognitive complaint and slow gait speed and/or increased FTSS time in participants without either dementia and mobility disabilities at baseline. Individuals with dementia were prospectively diagnosed during the physical and neuropsychological assessments included in the 7-year follow-up. RESULTS: The prevalence of MCR was around 7% when using an exclusive motor criterion, either slow gait speed or increased FTSS time, and was 20.9% when MCR subgroups were pooled. MCR was positively associated with incident dementia regardless of its type, and with Alzheimer disease in the slow gait speed MCR subgroup [odds ratio (OR) > 2.18 with P ≤ 0.037] but not with non-Alzheimer dementia. No significant association between incident dementia and MCR defined using increased FTSS time was shown. CONCLUSIONS: Our findings confirm that MCR is associated with incident dementia and that slow gait speed is the appropriate motor criterion for detecting dementia risk.

Motoric cognitive risk syndrome and mortality: results from the EPIDOS cohort.

BACKGROUND AND PURPOSE: Cognitive impairment, slow walking speed and motoric cognitive risk syndrome (MCR) have separately been associated with an increased risk for mortality in the short term. The aim of the study was to examine the association of MCR and its components [i.e. subjective cognitive complaint (SCC) and slow walking speed] with short-, medium- and long-term mortality in older community-dwellers. METHODS: In all, 3778 participants from the Epidémiologie de l'Ostéoporose (EPIDOS) study were selected. MCR was defined as the combination of slow walking speed and SCC in participants without major neurocognitive disorders. Deaths were prospectively recorded using mail, phone calls, questionnaires and/or the French national death registry at 5, 10, 15 and 19 (end of follow-up period) years. RESULTS: Over the follow-up of 19 years, 80.5% (n = 3043) participants died. Slow walking speed and MCR were associated with mortality [hazard ratio (HR) 1.20 with P = 0.004 for slow walking speed and HR = 1.26 with P = 0.002 for MCR at 10 years; HR = 1.27 with P ≤ 0.001 for slow walking speed and HR = 1.22 with P = 0.001 for MCR at 15 years; HR = 1.41 with P ≤ 0.001 at 19 years for slow walking speed and MCR]. There was no association between SCC and mortality. Kaplan-Meier distributions of mortality showed that participants with MCR and slow walking speed died earlier compared to healthy participants and those with SCC (P < 0.001). CONCLUSIONS: Slow walking speed and MCR were associated with an increased risk for mortality at the medium and long term, whereas no association was found with SCC.

Neural correlates of gait variability in people with multiple sclerosis with fall history.

BACKGROUND AND PURPOSE: The aim was to investigate the association between step time variability and related brain structures in accordance with fall status in people with multiple sclerosis (PwMS). METHODS: The study included 225 PwMS. Whole-brain magnetic resonance imaging was performed with a high-resolution 3.0 T magnetic resonance scanner in addition to volumetric analysis based on 3D T1-weighted images using the FreeSurfer image analysis suite. Step time variability was measured with an electronic walkway. Participants were defined as 'fallers' (at least two falls during the previous year) and 'non-fallers'. RESULTS: In all, 105 PwMS were defined as fallers and had a greater step time variability compared to non-fallers [5.6% (SD = 3.4) vs. 3.4% (SD = 1.5); P = 0.001]. MS fallers exhibited a reduced volume in the left caudate and both cerebellum hemispheres compared to non-fallers. On using a linear regression analysis no association was found between gait variability and related brain structures in the total cohort and the non-fallers group. However, the analysis found an association between the left hippocampus and left putamen volumes with step time variability in the faller group: P = 0.031, 0.048, respectively, controlling for total cranial volume, walking speed, disability, age and gender. Nevertheless, according to the hierarchical regression model, the contribution of these brain measures to predict gait variability was relatively small compared to walking speed. CONCLUSIONS: An association between low left hippocampal, putamen volumes and step time variability was found in PwMS with a history of falls, suggesting that brain structural characteristics may be related to falls and increased gait variability in PwMS.

Brain comorbidities in normal pressure hydrocephalus.

BACKGROUND AND PURPOSE: This cross-sectional study aims to compare gait changes after the cerebrospinal fluid (CSF) tap test between normal pressure hydrocephalus patients with and without brain comorbidities (NPH+ and NPH- respectively) and then to identify significant contributors to a poor CSF tap test amongst individuals with NPH+. METHODS: Gait changes (during the single task and the dual task of backward counting) were quantified before and 24 h after the CSF tap test with an optoelectronic system in 52 NPH patients (77.4 ± 6.0 years; 34.6% women). Changes after the CSF tap test in stride time variability (STV, %) were our main outcome. CSF Alzheimer's disease biomarkers, cerebrovascular white matter changes assessed with brain imaging and neurodegenerative diseases with parkinsonian syndrome represented the three individual brain comorbidities. RESULTS: Brain comorbidities were frequently identified, NPH+ patients representing 40 patients of our sample (76.9%). NPH- patients improved their STV better in the single task (delta of STV = -58.6% ± 54.3% vs. -14.1% ± 62.0%; P = 0.031) and in the dual task (delta of STV =-32.2% ± 33.7% vs. 6.3% ± 58.4%; P = 0.028) after the CSF tap test than NPH+ patients. Amongst NPH+ individuals, only comorbid Alzheimer's disease was associated with STV increase (i.e. deterioration of gait) in the dual task [ß 38.4; 95% confidence interval (5.64; 71.24); P = 0.023] after the CSF tap test, whilst it was borderline in the single task [ß 35.0; 95% confidence interval (-1.97; 71.90); P = 0.063]. CONCLUSIONS: Brain comorbidities affect gait improvement after the CSF tap test in NPH patients; this influence is driven by Alzheimer's disease-related pathology.

Postural control is associated with cognition and fear of falling in patients with multiple sclerosis.

Multiple sclerosis (MS) is a chronic inflammatory and neurodegenerative disease affecting various neurological domains, such as postural control, cognition, fear of falling, depression-anxiety, and fatigue. This study examined the associations of cognitive functions, fear of falling, depression-anxiety, and fatigue with postural control in patients with MS. Postural control (sway velocity) of 63 patients with MS (age 39.0 ± 8.9 years; %female 57%; Expanded Disability Status Scale score median (interquartile range) 2.0 (1.5)) was recorded on two platforms at stable and unstable conditions. Cognition, fear of falling, depression-anxiety, and fatigue were evaluated by a comprehensive neuropsychological assessment. The associations between these domains and postural control have been measured by multivariable linear regression (adjusted for age, gender, disability, and education). In stable condition, only working memory was associated with postural control (p < 0.05). In unstable condition, working memory, executive functions, attention/processing speed, and fear of falling were associated with postural control (p < 0.05). Specific cognitive domains and fear of falling were associated with postural control in MS patients, particularly in unstable condition. These findings highlight the association of cognitive functions and fear of falling with postural control in MS.

The spectrum of pre-dementia stages: cognitive profile of motoric cognitive risk syndrome and relationship with mild cognitive impairment.

BACKGROUND AND PURPOSE: Motoric cognitive risk (MCR) syndrome is a pre-dementia syndrome. There is little information on the cognitive profile of individuals with MCR syndrome and its overlap with mild cognitive impairment (MCI) syndrome. This study aimed to examine and compare the cognitive performance of non-demented older community dwellers with and without MCR and MCI syndromes. METHODS: A total of 291 non-demented individuals were selected from the Gait and Alzheimer Interactions Tracking study, which is a cross-sectional study. All participants were referred to a memory clinic. Individuals with and without MCR were separated into those with and without MCI. Cognitive performance was measured using the scores of the Mini Mental Status Examination, Frontal Assessment Battery, Free and Cued Selective Reminding Test, Trail Making Test part A and B, and Stroop test. RESULTS: The prevalence of MCI was 40.1% and that of MCR was 18.2%, with a higher prevalence of MCI in MCR group compared with the non-MCR group (47.2% vs. 39.5%). Individuals with MCR and MCI syndromes had poorer cognitive performance in all domains compared with those without MCR (P < 0.005), except for the ratio part III: part I of the Stroop test (P = 0.345). The association between cognitive performance and MCR syndrome was worse on the Mini Mental Status Examination score [effect size, -0.57 (95% confidence interval, -1.02 to -0.12)] and Trail Making Test part B [effect size, 0.59 (95% confidence interval, 0.14-1.04)] in individuals with MCR and MCI syndromes. CONCLUSIONS: Motoric cognitive risk syndrome is associated with low global cognitive performance. Association of MCR and MCI syndromes is characterized by a worse cognitive performance.

Gait phenotype from mild cognitive impairment to moderate dementia: results from the GOOD initiative.

BACKGROUND AND PURPOSE: The differences in gait abnormalities from the earliest to the later stages of dementia and in the different subtypes of dementia have not been fully examined. This study aims to compare spatiotemporal gait parameters in cognitively healthy individuals, patients with amnestic mild cognitive impairment (MCI) and non-amnestic MCI, and patients with mild and moderate stages of Alzheimer's disease (AD) and non-Alzheimer's disease (non-AD). METHODS: Based on a cross-sectional design, 1719 participants (77.4 ± 7.3 years, 53.9% female) were recruited from cohorts from seven countries participating in the Gait, Cognition and Decline (GOOD) initiative. Mean values and coefficients of variation of spatiotemporal gait parameters were measured during normal pace walking with the GAITRite system at all sites. RESULTS: Performance of spatiotemporal gait parameters declined in parallel with the stage of cognitive decline from MCI status to moderate dementia. Gait parameters of patients with non-amnestic MCI were more disturbed compared to patients with amnestic MCI, and MCI subgroups performed better than demented patients. Patients with non-AD dementia had worse gait performance than those with AD dementia. This degradation of gait parameters was similar between mean values and coefficients of variation of spatiotemporal gait parameters in the earliest stages of cognitive decline, but different in the most advanced stages, especially in the non-AD subtypes. CONCLUSIONS: Spatiotemporal gait parameters were more disturbed in the advanced stages of dementia, and more affected in the non-AD dementias than in AD. These findings suggest that quantitative gait parameters could be used as a surrogate marker for improving the diagnosis of dementia.

Improvement in executive subfunctions following cerebrospinal fluid tap test identifies idiopathic normal pressure hydrocephalus from its mimics.

BACKGROUND AND PURPOSE: Patients with idiopathic normal pressure hydrocephalus (iNPH) present cognitive deficits that overlap with other neurological conditions such as Parkinson's disease or vascular dementia, therefore mimicking iNPH. This prospective study aimed to compare cognitive performances between iNPH and iNPH mimics before and after cerebrospinal fluid (CSF) tapping. METHODS: A total of 57 patients with suspicion of iNPH (75.84 ± 6.42 years; 39% female) were included in this study (37 iNPH and 20 iNPH mimics). Neuropsychological assessments were performed before and 24 h after CSF tapping of 40 ml. Multivariate logistic regressions were used to examine the association between iNPH and cognitive functions, adjusted for age, education, baseline cognitive assessment and disease duration. RESULTS: Both groups presented the same baseline cognitive performances. After CSF tapping, iNPH patients improved their semantic (P = 0.001) and phonemic verbal fluencies (P = 0.001), whereas iNPH mimics presented similar performances to before CSF tapping. The phonemic verbal fluency (odds ratio 1.43, 95% confidence interval 1.05; 1.96) and the Color Trails Test (odds ratio 0.10, 95% confidence interval 0.01; 0.76) improvements were the two discriminative cognitive tests that identified iNPH from iNPH mimics. CONCLUSION: Improvement in executive subfunctions after CSF tapping identified iNPH patients from other neurological conditions that mimic iNPH. These findings respond to clinical issues encountered on a daily basis and would improve the diagnostic process of iNPH.

Towards a Comprehensive Framework for Complex Walking tasks: Characterization, Behavioral Adaptations, and Clinical Implications in Ageing and Neurological Populations.

Complex walking tasks, including change of direction, patterns and rhythms, require more attentional resources than simple walking and significantly impact walking performance, especially among ageing and neurological populations. More studies are focusing on complex walking situations, with or without the addition of cognitive tasks, creating a multitude of walking situations. Facing the lack of a clear and extensive definition of complex walking, this narrative review aims to identify and more precisely characterize situations and related tests, gain a better understanding of the behavioral adaptations in ageing and neurological populations, and report the clinical applications of complex walking. Based on the studies gathered, we propose a framework that categorizes the different forms of complex walking, considering whether a cognitive task is added or not, as well as the number of distinct objectives within the situation. We observed that combining complex walking tasks with a cognitive assignment places even greater strain on attentional resources, resulting in a more pronounced decline in walking or cognitive performance, or both. This work highlights the relevance of the complex walking as a simple tool for the early detection of cognitive impairments and the risk of falls, and its potential value in cognitive-motor rehabilitation. Future studies should explore the diversity of complex walking tasks in real-life simulated through extended virtual environments.

Systemic cytokines related to memory function 6-9 months and 12-15 months after SARS-CoV-2 infection.

Cognitive symptoms persisting beyond the acute phase of COVID-19 infection are commonly described for up to 2 years after infection. The relationship between cognitive performance, in particular episodic memory processes observed chronically after infection, and cytokine levels in the acute phase of COVID-19 has not yet been identified in humans. To determine whether the levels of cytokines IL1ß, IL-6 and TNFα secreted in the acute phase of SARS-CoV-2 infection are associated and predict verbal and visuospatial episodic memory performance in humans 6 to 9 months and 12 to 15 months post-infection. The associations and predictive value of the concentration of cytokines measured in acute phase (IL-1ß, IL-6, TNFα) from plasma samples of N = 33 hospitalized COVID-19 patients (mean age 61 years, 39-78, 65% in intensive care) in relation to their verbal and visuospatial episodic memory performance measured at 6-9 months and 12-15 months post-infection were analyzed. To do this, we used Spearman correlations and generalised linear mixed models. IL-1ß levels were associated with verbal episodic memory total recall scores 6-9 months post-infection. At 12-15 months post-infection IL-6 predicted verbal episodic memory score. This study demonstrated that the severity of inflammatory reaction at acute phase of SARS-CoV-2 infection predicts verbal episodic memory performance in the long-term post-infection.

Derivation and validation of a Short Form of the Mini-Mental State Examination for the screening of dementia in older adults with a memory complaint.

BACKGROUND AND PURPOSE: To validate a Short Form of the Mini-Mental State Examination (SMMSE) as a screening test for dementia in older ambulatory individuals followed in a memory clinic for a memory complaint. METHODS: A total of 202 cognitively healthy individuals, 100 individuals with a mild cognitive impairment and 304 demented individuals sent for a memory complaint by their primary care physician to a memory clinic were prospectively included in this cross-sectional study. They were randomized into derivation (n = 303) and validation (n = 303) groups. The SMMSE score was built from six memory items of MMSE, with a score ranging from 0 to 6 (i.e. best performance). RESULTS: The receiver operating characteristic curve showed an area under the curve of 0.98 for the derivation group and 0.97 for the validation group without differences between curves (P = 0.254). The cut-off between the sensitivity and the specificity of the SMMSE score for clinically diagnosed dementia was ≤4. The performance of the SMMSE for the diagnosis of dementia was high in the derivation and validation groups: sensitivity at 93.1% and 93.8%, specificity at 93.8% and 90.5%, positive predictive value at 94.3% and 90.1%, negative predictive value at 92.5% and 94.0%, likelihood ratio of positive test at 14.9 and 9.8 and of negative test at 0.07 and 0.07, respectively. CONCLUSIONS: The Short Form of the Mini-Mental State Examination was a good screening test for dementia in older individuals followed in a memory clinic for a memory complaint. The next step should be the confirmation of its discriminative value in older primary care patients.

Frequency of Abnormally Low Neuropsychological Scores in Post-COVID-19 Syndrome: the Geneva COVID-COG Cohort.

OBJECTIVE: Several studies have reported poor long-term neuropsychological performances in patients following severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection, but none has yet considered the effect of administering multiple intercorrelated neuropsychological tests and assessed the frequency of cognitive deficits in a normative population. Our aim was therefore to assess the presence of cumulative neuropsychological deficits in an actual post-coronavirus disease of 2019 (COVID-19) comparison group versus one simulated using Monte-Carlo methods. METHOD: Validated neuropsychological Monte-Carlo simulation methods were applied to scores from a battery of neuropsychological tests (memory, executive, attentional, perceptual, logical reasoning, language, and ideomotor praxis) administered to 121 patients who had had mild, moderate, or severe COVID-19 (mean age: 56.70 years; 32% women), 222 ± 43 days post-infection. The cumulative percentages of the three severity subgroups were compared with the results of a false discovery rate-corrected probability analysis based on normative data. RESULTS: The cumulative percentages of deficits in memory and executive functions among the severe and moderate patients were significantly higher than those estimated for the normative population. Moderate patients also had significantly more deficits in perception and logical reasoning. In contrast, the mild group did not have significantly more cumulative deficits. CONCLUSIONS: Moderate and severe forms of COVID-19 cause greater long-term neuropsychological deficits than those that would be found in a normative population, reinforcing the hypothesis of long-term effects of SARS-CoV-2 on cognitive function, independent of the severity of the initial infection.

Acute TNFα levels predict cognitive impairment 6-9 months after COVID-19 infection.

BACKGROUND: A neurocognitive phenotype of post-COVID-19 infection has recently been described that is characterized by a lack of awareness of memory impairment (i.e., anosognosia), altered functional connectivity in the brain's default mode and limbic networks, and an elevated monocyte count. However, the relationship between these cognitive and brain functional connectivity alterations in the chronic phase with the level of cytokines during the acute phase has yet to be identified. AIM: Determine whether acute cytokine type and levels is associated with anosognosia and functional patterns of brain connectivity 6-9 months after infection. METHODS: We analyzed the predictive value of the concentration of acute cytokines (IL-1RA, IL-1ß, IL-6, IL-8, IFNγ, G-CSF, GM-CSF) (cytokine panel by multiplex immunoassay) in the plasma of 39 patients (mean age 59 yrs, 38-78) in relation to their anosognosia scores for memory deficits via stepwise linear regression. Then, associations between the different cytokines and brain functional connectivity patterns were analyzed by MRI and multivariate partial least squares correlations for the whole group. RESULTS: Stepwise regression modeling allowed us to show that acute TNFα levels predicted (R2 = 0.145; ß = -0.38; p = .017) and were associated (r = -0.587; p < .001) with scores of anosognosia for memory deficits observed 6-9 months post-infection. Finally, high TNFα levels were associated with hippocampal, temporal pole, accumbens nucleus, amygdala, and cerebellum connectivity. CONCLUSION: Increased plasma TNFα levels in the acute phase of COVID-19 predict the presence of long-term anosognosia scores and changes in limbic system functional connectivity.

Vitamin D insufficiency and mild cognitive impairment: cross-sectional association.

BACKGROUND: Low serum 25-hydroxyvitamin D (25OHD) concentrations have been associated with dementia. The association with mild cognitive impairment (MCI) has not yet been explored. Our aim was to examine the association between vitamin D status and MCI status amongst older community-dwellers with subjective memory complaint. METHODS: Ninety-five non-demented Caucasian community-dwellers with subjective memory complaint (mean, 71.1 ± 6.4 years; 54.7% women) included in the Gait and Alzheimer Interaction Tracking (GAIT) study were categorized into two groups according to Winblad et al. consensus criteria [i.e., subjects with MCI or cognitively healthy individuals (CHI)]. Serum 25OHD concentration was divided into quartiles, the fourth quartile corresponding to the highest 25OHD concentration. The cross-sectional associations between 25OHD concentrations and MCI were modeled using logistic regressions. Age, gender, body mass index, number of comorbidities, education level, Mini-Mental State Examination score, Frontal Assessment Battery score, Geriatric Depression Scale score, creatinine clearance, and season tested were considered as potential confounders. RESULTS: Compared to CHI, patients with MCI (n = 43; mean, 71.4 ± 5.6 years; 34.9% women) had lower mean serum 25OHD concentrations (P = 0.006) and belonged more often to the lower quartiles compared to the highest quartile (P = 0.03). Increased serum 25OHD concentration was associated with a lower risk of MCI [adjusted odds ratio (OR) = 0.96, P = 0.002]. Accordingly, lower quartiles of 25OHD were positively associated with MCI whilst using the highest quartile as reference (adjusted OR = 25.46, P = 0.002 for the first quartile; adjusted OR = 6.89, P = 0.03 for the second quartile; and adjusted OR = 10.29, P = 0.02 for the third quartile). CONCLUSIONS: Low 25OHD concentrations were associated with MCI status in older non-demented community-dwellers with subjective memory complaint.

Adapted timed up and go: a rapid clinical test to assess gait and cognition in multiple sclerosis.

BACKGROUND/AIMS: To measure the Timed Up and Go (TUG), imagined TUG (iTUG), and the difference of time between these two tests (delta time) in 20 patients with relapsing-remitting multiple sclerosis (RRMS) and 20 healthy age-matched controls and to examine whether an association with cognitive functions, motor impairment, and behavioral changes can be determined. METHODS: The mean ± SD of TUG, iTUG and delta time were used as outcomes. Spatiotemporal gait parameters were recorded by a 12-camera optoelectronic system during straight walking at usual self-selected speed. Cognitive functions were assessed by a standardized neuropsychological examination. RESULTS: Patients performed the TUG slower than the controls (10.00 ± 1.70 s vs. 8.71 ± 1.04 s, p = 0.01, respectively). The TUG was correlated with gait parameters, cognitive functions, and behavior, whereas delta time was correlated only with cognitive functions. CONCLUSION: TUG represents an interesting test to reveal subtle deficits in RRMS patients with low disability and is related to motor, cognitive, and behavioral functioning. Combining with the TUG, delta time could easily give additional information on specific cognitive functions in the assessment of patients with RRMS.

Monocytosis in the acute phase of SARS-CoV-2 infection predicts the presence of anosognosia for cognitive deficits in the chronic phase.

Reduced awareness of neuropsychological disorders (i.e., anosognosia) is a striking symptom of post-COVID-19 condition. Some leukocyte markers in the acute phase may predict the presence of anosognosia in the chronic phase, but they have not yet been identified. This study aimed to determine whether patients with anosognosia for their memory deficits in the chronic phase presented specific leukocyte distribution in the acute phase, and if so, whether these leukocyte levels might be predictive of anosognosia. First, we compared the acute immunological data (i.e., white blood cell differentiation count) of 20 patients who displayed anosognosia 6-9 months after being infected with SARS-CoV-2 (230.25 ± 46.65 days) versus 41 patients infected with SARS-Cov-2 who did not develop anosognosia. Second, we performed an ROC analysis to evaluate the predictive value of the leukocyte markers that emerged from this comparison. Blood circulating monocytes (%) in the acute phase of SARS-CoV-2 infection were associated with long-term post-COVID-19 anosognosia. A monocyte percentage of 7.35% of the total number of leukocytes at admission seemed to predict the presence of chronic anosognosia 6-9 months after infection.

Interest of dual-task-related gait changes in idiopathic normal pressure hydrocephalus.

BACKGROUND: Gait disorders in patients with idiopathic normal pressure hydrocephalus (iNPH) share similar characteristics found in pathologies presenting with higher-level gait disorders that have been specifically associated with gait changes during walking while simultaneously performing an attention-demanding task (i.e. dual tasking). The current study assessed the effect of cerebrospinal fluid (CSF) tapping on quantitative gait modification during single and dual tasking in patients with a suspicion of iNPH. METHODS: Of 53 patients suspected of iNPH, 18 have been included in this study. Gait analysis during single- and dual-task condition (walking and backward counting) before and after tapping of 40 ml CSF has been performed. RESULTS: Gait speed (P < 0.01) and stride length (P < 0.05) were significantly improved during dual-task conditions after CSF tapping compared to the gait performance before spinal tapping, without such improvement for gait parameters during single-tasking. CONCLUSION: Dual-tasking condition better reveals gait improvement after CSF tapping than single-tasking in patients suspected of iNPH.

Decrease in gait variability while counting backward: a marker of "magnet effect"?

Counting backward (CB) and walking are both rhythmic tasks. An improvement of CB performance has been reported while walking, and has been interpreted as a "magnet effect" which is the tendency of biological oscillators to attract each other. The objective of this study was to compare the coefficient of variation (CoV) of stride time (ST) and the number of enumerated figures while single- and dual-tasking between older adults who increased and decreased their CoV of ST while CB. The number of enumerated figures and the CoV of ST under single-task (i.e., CB while sitting or walking alone) and dual-task (i.e., CB while walking) were measured among 100 community-dwelling older subjects (mean, 69.8 ± 0.07 years). Subjects were separated into two groups according to the dual-task-related changes in CoV of ST (i.e., either above or below the mean value of CoV of ST under single-task). Seventeen participants decreased their CoV of ST while CB compared to usual walking (2.6 ± 1.6% vs. 2.0 ± 1.3%, P < 0.001), while 83 increased their CoV of ST (1.7 ± 0.6% vs 3.4 ± 2.3%, P < 0.001). The subjects who decreased their CoV of ST had a tendency to enumerate more figures while walking compared to sitting (20.9 ± 6.3 vs 19.4 ± 4.7, P = 0.046) unlike those who increased their CoV of ST (20.3 ± 5.0 vs 21.8 ± 6.0 while sitting, P = 0.001). We found that most of subjects had worse gait and CB performance while dual-tasking. Conversely, a limited number of subjects improved significantly their gait performance and simultaneously had a tendency to improve their CB performance while walking compared to sitting. This behavior was observed only among subjects with the highest gait variability and could be interpreted as an implicit strategy based on the "magnet effect".