Longitudinal Associations Between Falls and Risk of Gait Decline: Results From the Central Control of Mobility and Aging Study.

OBJECTIVE: To examine whether falls are associated with longitudinal changes in different gait domains and onset of clinical gait abnormalities. DESIGN: Longitudinal study. SETTING: General community. PARTICIPANTS: Ambulatory older adults free of dementia (N=428; mean age, 77.8±6.4 years). INTERVENTIONS: Not applicable. MAIN OUTCOME MEASURES: Gait was assessed with a computerized walkway. Pace, rhythm, and variability (outcome measures) were derived from individual gait measures, using principal component analysis. Clinical gait abnormalities (neurologic, nonneurologic, mixed) were visually assessed by clinicians. Linear mixed-effects models were used to examine the associations between falls (the exposure variable coded as none, single, and multiple) and changes in gait domains. Multinomial logistic regression was used to examine associations between falls and the onset of clinical gait abnormalities. Models were adjusted for sex, education, age, body mass index, number of comorbidities, gait speed at the first follow-up, and time between the last fall and the first follow-up gait assessment. RESULTS: Pace declined while rhythm and variability increased at a faster rate (P<.05) among 32 participants with multiple falls in the first year of follow-up compared with 299 participants with no falls. Risk for clinical gait abnormalities between those with no falls, a single fall, or multiple falls was not different. CONCLUSIONS: Multiple falls predict future gait decline in multiple domains in aging. Interventions to prevent gait decline after multiple falls should be investigated.

Randomized Controlled Trial of Social Ballroom Dancing and Treadmill Walking: Preliminary Findings on Executive Function and Neuroplasticity From Dementia-at-Risk Older Adults.

This randomized controlled trial (NCT03475316) examined the relative efficacy of 6 months of social ballroom dancing and treadmill walking on a composite executive function score, generated from digit symbol substitution test, flanker interference, and walking while talking tasks. Brain activation during functional magnetic resonance imaging (fMRI) versions of these executive function tasks were secondary outcomes. Twenty-five dementia-at-risk older adults (memory impairment screen score of ≥3 to ≤6 and/or an Alzheimer's disease-8 Dementia Screening Interview of ≥1) were randomized in June 2019 to March 2020-16 completed the intervention before study termination due to the COVID-19 (eight in each group). Composite executive function scores improved post-intervention in both groups, but there was no evidence for between-group differences. Social dancing, however, generated greater improvements on digit symbol substitution test than treadmill walking. No intervention-related differences were observed in brain activation-although less hippocampal atrophy (tertiary) was observed following social dancing than treadmill walking. These preliminary findings are promising but need to be confirmed in future large-scale and sufficiently powered randomized controlled trials.

Longitudinal associations between falls and future risk of cognitive decline, the Motoric Cognitive Risk syndrome and dementia: the Einstein Ageing Study.

BACKGROUND: falls share risk factors with cognitive decline but whether falls predict cognitive decline, pre-dementia syndromes and dementia is poorly understood. OBJECTIVES: this study aimed to examine if falls are associated with cognitive decline in specific domains and the risk of Motoric Cognitive Risk (MCR) syndrome and dementia. DESIGN: cross-sectional study. METHODS: in older people (age 80.6 ± 5.3 years) free of dementia at baseline, the number of falls (none, one or multiple) during the year before enrolment and the first year of follow-up (exposure) were recorded. Decline in specific cognitive functions (global cognition, episodic verbal memory, verbal fluency, working memory, response inhibition and processing speed-attention), incident MCR and incident dementia were outcome measures. Linear mixed effects models were used to examine the associations between falls and cognitive decline, adjusting for confounders. Cox proportional hazards models were used to determine if falls predicted risk of incident MCR or dementia. RESULTS: of 522 eligible participants, 140 had a single fall and 70 had multiple falls. Multiple falls were associated with a greater decline in global cognition, episodic memory, verbal fluency and processing speed-attention compared to those with no falls (P < 0.05). Over a median follow-up of 1.0 years 36 participants developed MCR and 43 participants developed dementia. Those with multiple falls had a two-fold increased risk of MCR compared to those with no falls, but no increased risk of developing dementia. CONCLUSIONS: multiple falls may be an important marker to identify older people at greater risk of future cognitive decline and incident MCR.

The Associations Between Grey Matter Volume Covariance Patterns and Gait Variability-The Tasmanian Study of Cognition and Gait.

Greater gait variability predicts dementia. However, little is known about the neural correlates of gait variability. The aims of this study were to determine (1) grey matter volume covariance patterns associated with gait variability and (2) whether these patterns were associated with specific cognitive domains. Participants (n = 351; mean age 71.9 ± 7.1) were randomly selected from the Southern Tasmanian electoral roll. Step time, step length, step width and double support time were measured using an electronic walkway. Gait variability was calculated as the standard deviation of all steps for each gait measure. Voxel-based morphometry and multivariate covariance-based analyses were used to identify grey matter patterns associated with each gait variability measure. The individual expressions of grey matter patterns were correlated with processing speed, memory, executive and visuospatial functions. The grey matter covariance pattern of double support time variability included frontal, medial temporal, anterior cingulate, insula, cerebellar and striatal regions. Greater expression of this pattern was correlated with poorer performance in all cognitive functions (p < 0.001). The covariance pattern of step length variability included frontal, temporal, insula, occipital and cerebellar regions and was correlated with all cognitive functions (p < 0.05), except memory (p = 0.76). The covariance pattern of step width variability was limited to the cerebellum and correlated only with memory (p = 0.047). No significant pattern was identified for step time variability. In conclusion, different grey matter covariance patterns were associated with individual gait variability measures. These patterns were also correlated with specific cognitive functions, suggesting common neural networks may underlie both gait and cognition.

Gray matter volume covariance networks associated with dual-task cost during walking-while-talking.

We studied gray matter volume covariance networks associated with normal pace walking (NPW) speed and dual-task costs (DTCs) during walking-while-talking (WWT)-a mobility stress test that involves walking while reciting alternate letters of the alphabet. Using a multivariate covariance-based analytic approach, we identified gray matter networks associated with NPW speed (mean 102.1 cm/s ±22.5 cm/s) and DTC (percent difference in gait speed between NPW and WWT, mean 25.9% ± 18.8%) in 139 older adults without dementia (M = 75.3 ± 6.1 years). The gray matter network associated with NPW was primarily composed of supplementary motor area, precuneus cortex, and the middle frontal gyrus. Greater expression of this NPW network was associated with better processing speed (trail-making test A [r = -0.30, p = 0.005]) and executive function (trail-making test B - A [r = -0.43, p < 0.0001]). The gray matter network associated with DTC was primarily composed of medial prefrontal, cingulate, and thalamic regions. Greater expression of this DTC network was associated with better episodic memory performance on the free and cued selective reminding test (r = 0.30, p = 0.007). These results suggest that NPW speed and DTC are supported by different networks, and are associated with different cognitive domains.

Functional connectivity associated with gait velocity during walking and walking-while-talking in aging: a resting-state fMRI study.

Gait decline is common among older adults and is a risk factor for adverse outcomes. Poor gait performance in dual-task conditions, such as walking while performing a secondary cognitive interference task, is associated with increased risk of frailty, disability, and death. Yet, the functional neural substrates that support locomotion are not well established. We examined the functional connectivity associated with gait velocity in single- (normal pace walking) and dual-task (walking while talking) conditions using resting-state functional Magnetic Resonance Imaging (fMRI). We acquired 6 minutes of resting-state fMRI data in 30 cognitively healthy older adults. Independent components analyses were performed to separate resting-state fMRI data into group-level statistically independent spatial components that correlated with gait velocity in single- and dual-task conditions. Gait velocity in both task conditions was associated with similar functional connectivity in sensorimotor, visual, vestibular, and left fronto-parietal cortical areas. Compared to gait velocity in the single-task condition, the networks associated with gait velocity in the dual-task condition were associated with greater functional connectivity in supplementary motor and prefrontal regions. Our findings show that there are partially overlapping functional networks associated with single- and dual-task walking conditions. These initial findings encourage the future use of resting-state fMRI as tool in developing a comprehensive understanding of age-related mobility impairments.

Behavioral and neural correlates of imagined walking and walking-while-talking in the elderly.

Cognition is important for locomotion and gait decline increases the risk for morbidity, mortality, cognitive decline, and dementia. Yet, the neural correlates of gait are not well established, because most neuroimaging methods cannot image the brain during locomotion. Imagined gait protocols overcome this limitation. This study examined the behavioral and neural correlates of a new imagined gait protocol that involved imagined walking (iW), imagined talking (iT), and imagined walking-while-talking (iWWT). In Experiment 1, 82 cognitively-healthy older adults (M=80.45) walked (W), iW, walked while talking (WWT) and iWWT. Real and imagined walking task times were strongly correlated, particularly real and imagined dual-task times (WWT and iWWT). In Experiment 2, 33 cognitively-healthy older adults (M=73.03) iW, iT, and iWWT during functional magnetic resonance imaging. A multivariate Ordinal Trend (OrT) Covariance analysis identified a pattern of brain regions that: (1) varied as a function of imagery task difficulty (iW, iT and iWWT), (2) involved cerebellar, precuneus, supplementary motor and other prefrontal regions, and (3) were associated with kinesthetic imagery ratings and behavioral performance during actual WWT. This is the first study to compare the behavioral and neural correlates of imagined gait in single and dual-task situations, an issue that is particularly relevant to elderly populations. These initial findings encourage further research and development of this imagined gait protocol as a tool for improving gait and cognition among the elderly.

Longitudinal Associations of Social Support and Gait Speed Decline in Aging.

BACKGROUND: Social support predicts functional and cognitive decline in aging. Yet, the associations between social support and gait speed decline-a functional vital sign-are not well understood. This study examined associations between social support and gait speed decline in aging. METHODS: Social support and gait data from 542 older adults without dementia were examined (mean age 76.1 ±â€…6.5 years). Baseline emotional support, tangible support, affectionate support, positive social interactions, and overall support from the Medical Outcomes Study Social Support Survey were the predictors of interest. Annual change in simple (normal pace walking) and complex (walking while reciting alternate letters of the alphabet) gait speed (cm/s) were the outcomes of interest. Linear mixed effects models examined associations between social support and gait speed decline, after adjusting for gender, race, depressive symptoms, overall cognition, and comorbidities. RESULTS: The mean annual change in gait speed was 1.8 cm/s during simple walking and 1.13 cm/s during complex walking. Tangible support was the only category of social support that predicted decline in simple and complex gait speed over a median follow-up of 3 years. The annual decline in gait speed was 0.51 cm/s (p = .008, 95% confidence intervals [CI] 0.13, 0.89) and 0.58 cm/s (p = .007, CI 0.16, 1.0) greater among those with low tangible support than in those with high tangible support during simple and complex walking, respectively. CONCLUSIONS: Tangible support is a potentially modifiable risk factor for gait speed decline. Further study is needed to examine mechanisms behind the observed associations and the potential for intervention.

Difference-Making Pathways to Frailty Through Social Factors: A Configurational Analysis.

BACKGROUND AND OBJECTIVES: Social disconnection is highly prevalent in older adults and is associated with frailty. It is unclear which aspects of social disconnection are most associated with frailty, which ones are difference-making, and which combination of social factors are directly linked to frailty. RESEARCH DESIGN AND METHODS: We conducted a secondary coincidence analysis (CNA) of 1,071 older adults from the Rush Memory and Aging Project (mean age 79.3 ± 7.1; 75.8% female) to identify combinations of social factors that are difference-making for frailty. We included 7 demographic (e.g., age, sex, socioeconomic status) and structural (e.g., social network), functional (e.g., social support, social activity), and quality (e.g., loneliness) aspects of social connection. An established cut score of 0.2 on a frailty index was used to define frailty as the outcome. RESULTS: CNA produced 46 solution models for the presence of frailty in the data set. The top-scoring model was underfit, leaving a final complex solution path for frailty with the highest fit-robustness score that met the fit parameter cutoffs. We found that the combination of loneliness, low social activity, and older age was present 82% of the time when frailty was present. DISCUSSION AND IMPLICATIONS: The combination of loneliness, social activity, and old age is difference-making for frailty, and supports the inclusion of social factors in frailty prevention and intervention. Further research is needed in diverse data sets to better understand the interrelationships between the 3 aspects of social connection and frailty.

Loneliness predicts decreased physical activity in widowed but not married or unmarried individuals.

Background: Physical activity is associated with improved health and function in older adults, yet most older adults are sedentary. Loneliness is associated with decreased physical activity at the cross-section, but longitudinal studies are scarce. We examined longitudinal associations between loneliness and physical activity-and whether they were modified by marital status and network size (the number of children, relatives, and friends a person interacts with at least once a month). Methods: We analyzed data from 1,931 older adults without dementia at baseline from the Rush Memory and Aging Project with a mean follow-up of 4.8 years (mean age 79.6 ± 7.7, 74.9% women). Loneliness was assessed using the de Jong Gierveld Loneliness Scale. Physical activity was assessed as the frequency with which participants engaged in five categories of activities (e.g., walking, gardening, calisthenics, bicycling, and swimming). Linear mixed effects models examined associations between baseline loneliness and change in physical activity over time after adjusting for demographics, depressive symptoms, global cognition, disability, network size, marital status, social support, and social and cognitive activities. We assessed for effect modification by marital status and network size. Results: Associations between loneliness and physical activity differed by marital status. In widowed individuals, baseline loneliness was associated with a 0.06 h/week greater decrease in physical activity per year compared to those who were not lonely (p = 0.005, CI -0.1, 0.02)-which equaled a 150% decrease in physical activity per year. Loneliness did not predict a statistically significant decrease in physical activity in married or unmarried individuals. Discussion: Loneliness is associated with decreased physical activity in widowed older adults and should be considered in the design of interventions to prevent or slow the decline in physical activity and promote healthy aging.

Linking Dementia Pathology and Alteration in Brain Activation to Complex Daily Functional Decline During the Preclinical Dementia Stages: Protocol for a Prospective Observational Cohort Study.

BACKGROUND: Progressive difficulty in performing everyday functional activities is a key diagnostic feature of dementia syndromes. However, not much is known about the neural signature of functional decline, particularly during the very early stages of dementia. Early intervention before overt impairment is observed offers the best hope of reducing the burdens of Alzheimer disease (AD) and other dementias. However, to justify early intervention, those at risk need to be detected earlier and more accurately. The decline in complex daily function (CdF) such as managing medications has been reported to precede impairment in basic activities of daily living (eg, eating and dressing). OBJECTIVE: Our goal is to establish the neural signature of decline in CdF during the preclinical dementia period. METHODS: Gait is central to many CdF and community-based activities. Hence, to elucidate the neural signature of CdF, we validated a novel electroencephalographic approach to measuring gait-related brain activation while participants perform complex gait-based functional tasks. We hypothesize that dementia-related pathology during the preclinical period activates a unique gait-related electroencephalographic (grEEG) pattern that predicts a subsequent decline in CdF. RESULTS: We provide preliminary findings showing that older adults reporting CdF limitations can be characterized by a unique gait-related neural signature: weaker sensorimotor and stronger motor control activation. This subsample also had smaller brain volume and white matter hyperintensities in regions affected early by dementia and engaged in less physical exercise. We propose a prospective observational cohort study in cognitively unimpaired older adults with and without subclinical AD (plasma amyloid-ß) and vascular (white matter hyperintensities) pathologies. We aim to (1) establish the unique grEEG activation as the neural signature and predictor of decline in CdF during the preclinical dementia period; (2) determine associations between dementia-related pathologies and incidence of the neural signature of CdF; and (3) establish associations between a dementia risk factor, physical inactivity, and the neural signature of CdF. CONCLUSIONS: By establishing the clinical relevance and biological basis of the neural signature of CdF decline, we aim to improve prediction during the preclinical stages of ADs and other dementias. Our approach has important research and translational implications because grEEG protocols are relatively inexpensive and portable, and predicting CdF decline may have real-world benefits. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/56726.

Cognitive reserve proxies are associated with age-related cognitive decline - Not age-related gait speed decline.

Cognition and gait share brain substrates in aging and dementia. Cognitive reserve (CR) allows individuals to cope with brain pathology and delay cognitive impairment and dementia. Yet, evidence for that CR is associated with age-related cognitive decline is mixed, and evidence for that CR is associated with age-related gait decline is limited. In 1,079 older (M Age = 75.4 years; 56.0% women) LonGenity study participants without dementia at baseline and up to 12 years of annual follow-up (M follow-up = 3.9 years, SD = 2.5 years), high CR inferred from cognitive (education years), physical (number of blocks walked per day; weekly physical activity days), and social (volunteering/working; living with someone) proxies were associated with slower rates of age-related decline in global cognition - not gait speed decline. Thus, cognitive, physical, and social CR proxies are associated with cognitive decline in older adults without dementia. The multifactorial etiology and earlier decline in gait than cognition may render it less modifiable by CR proxies later in life.

Hypothalamic MRI-derived microstructure is associated with neurocognitive aging in humans.

The hypothalamus regulates homeostasis across the lifespan and is emerging as a regulator of aging. In murine models, aging-related changes in the hypothalamus, including microinflammation and gliosis, promote accelerated neurocognitive decline. We investigated relationships between hypothalamic microstructure and features of neurocognitive aging, including cortical thickness and cognition, in a cohort of community-dwelling older adults (age range 65-97 years, n=124). Hypothalamic microstructure was evaluated with two magnetic resonance imaging diffusion metrics: mean diffusivity (MD) and fractional anisotropy (FA), using a novel image processing pipeline. Hypothalamic MD was cross-sectionally positively associated with age and it was negatively associated with cortical thickness. Hypothalamic FA, independent of cortical thickness, was cross-sectionally positively associated with neurocognitive scores. An exploratory analysis of longitudinal neurocognitive performance suggested that lower hypothalamic FA may predict cognitive decline. No associations between hypothalamic MD, age, and cortical thickness were identified in a younger control cohort (age range 18-63 years, n=99). To our knowledge, this is the first study to demonstrate that hypothalamic microstructure is associated with features of neurocognitive aging in humans.

Task demand influences relationships among sex, clustering strategy, and recall: 16-word versus 9-word list learning tests.

OBJECTIVE: We compared the relationships among sex, clustering strategy, and recall across different task demands using the 16-word California Verbal Learning Test-Second Edition (CVLT-II) and the 9-word Philadelphia (repeatable) Verbal Learning Test (PrVLT). BACKGROUND: Women generally score higher than men on verbal memory tasks, possibly because women tend to use semantic clustering. This sex difference has been established via word-list learning tests such as the CVLT-II. METHODS: In a retrospective between-group study, we compared how 2 separate groups of cognitively healthy older adults performed on a longer and a shorter verbal learning test. The group completing the CVLT-II had 36 women and 26 men; the group completing the PrVLT had 27 women and 21 men. RESULTS: Overall, multiple regression analyses revealed that semantic clustering was significantly associated with total recall on both tests' lists (P<0.001). Sex differences in recall and semantic clustering diminished with the shorter PrVLT word list. CONCLUSIONS: Semantic clustering uniquely influenced recall on both the longer and shorter word lists. However, serial clustering and sex influenced recall depending on the length of the word list (ie, the task demand). These findings suggest a complex nonlinear relationship among verbal memory, clustering strategies, and task demand.

Gait in cerebral small vessel disease, pre-dementia, and dementia: A systematic review.

BACKGROUND: The interrelationships between gait, cerebral small vessel disease (CSVD), and cognitive impairments in aging are not well-understood-despite their common co-occurrence. OBJECTIVE: To systematically review studies of gait impairment in CSVD, pre-dementia, and dementia, and to identify key gaps for future research and novel pathways toward intervention. METHODS: A Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA)-guided search strategy was implemented in PubMed to identify relevant studies. Potential articles (n = 263) published prior to 1 December 2021 were screened by two reviewers. Studies with sample sizes >20 and including some adults over > 65 years (n = 202) were included. RESULTS: The key findings were that (1) adverse gait and cognitive outcomes were associated with several (rather than select) CSVD pathologies distributed across the brain, and (2) poor gait and CSVD pathologies were more strongly associated with dementia with a vascular, rather than an Alzheimer's disease-related, cause. DISCUSSION: A better understanding of the interrelationships between gait performance in CSVD, pre-dementia, and dementia requires studies examining (1) comprehensive patterns in the clinical manifestations of CSVD, (2) racially/ethnically diverse samples, (3) samples followed for extended periods of time or across the adult life span, (4) non-traditional CSVD neuroimaging markers (e.g. resting-state functional magnetic resonance imaging (fMRI)), and (5) continuous (e.g. wearable sensors) and complex (e.g. dual-task) walking performance.

Neural signature of mobility-related everyday function in older adults at-risk of cognitive impairment.

Assessment of everyday activities is central to the diagnosis of dementia. Yet, little is known about brain processes associated with everyday functional limitations, particularly during early stages of cognitive decline. Twenty-six older adults (mean = 74.9 y) were stratified by risk using the Montreal Cognitive Assessment battery (MoCA, range: 0- 30) to classify individuals as higher (22-26) and lower risk (27+) of cognitive impairment. We investigated everyday function using a gait task designed to destabilize posture and applied Mobile Brain/Body Imaging. We predicted that participants would increase step width to gain stability, yet the underlying neural signatures would be different for lower versus higher risk individuals. Step width and fronto-parietal activation increased during visually perturbed input. Frontomedial theta increased in higher risk individuals during perturbed and unperturbed inputs. Left sensorimotor beta decreased in lower risk individuals during visually perturbed input. Modulations in theta and beta power were associated with MoCA scores. Our findings suggest that older adults at-risk of cognitive impairment can be characterized by a unique neural signature of everyday function.

Age-related changes in gait domains: Results from the LonGenity study.

BACKGROUND: Impairment in gait domains such as pace, rhythm, and variability are associated with falls, cognitive decline, and dementia. However, the longitudinal changes in these gait domains are poorly understood. The aim of this study was to examine age-related changes in gait domains overall and in those with cognitive impairment and mobility disability. METHODS: Participants were from the LonGenity study (n = 797; M Age=75.1 SD 6.5 years; 58.2% female) and were followed up to 12 years (Median=3.3; IQR: 1.1; 6.3). Gait speed and absolute values of step length, step time, cadence and, variability (standard deviation) of step length and step time during usual pace walking were assessed. Principal components analysis was used to obtain weighted combinations of three gait domains: pace (velocity, step length), variability (step length variability, step time variability) and rhythm (step time). Linear mixed effect models were used to examine age-related changes in gait domains overall, and in those with cognitive impairment and mobility disability at baseline. RESULTS: Pace declined, and rhythm increased (worsened) in an accelerating non-linear fashion. Variability gradually increased with age. Those with cognitive impairment had faster rates of change in pace and rhythm. Those with mobility disability had faster increases in rhythm. CONCLUSIONS: Age-related changes in gait domains are not uniform. Individuals with cognitive and mobility impairments are particularly vulnerable to accelerated change in pace and or rhythm.

Visual-somatosensory integration (VSI) as a novel marker of Alzheimer's disease: A comprehensive overview of the VSI study.

Identification of novel, non-invasive, non-cognitive based markers of Alzheimer's disease (AD) and related dementias are a global priority. Growing evidence suggests that Alzheimer's pathology manifests in sensory association areas well before appearing in neural regions involved in higher-order cognitive functions, such as memory. Previous investigations have not comprehensively examined the interplay of sensory, cognitive, and motor dysfunction with relation to AD progression. The ability to successfully integrate multisensory information across multiple sensory modalities is a vital aspect of everyday functioning and mobility. Our research suggests that multisensory integration, specifically visual-somatosensory integration (VSI), could be used as a novel marker for preclinical AD given previously reported associations with important motor (balance, gait, and falls) and cognitive (attention) outcomes in aging. While the adverse effect of dementia and cognitive impairment on the relationship between multisensory functioning and motor outcomes has been highlighted, the underlying functional and neuroanatomical networks are still unknown. In what follows we detail the protocol for our study, named The VSI Study, which is strategically designed to determine whether preclinical AD is associated with neural disruptions in subcortical and cortical areas that concurrently modulate multisensory, cognitive, and motor functions resulting in mobility decline. In this longitudinal observational study, a total of 208 community-dwelling older adults with and without preclinical AD will be recruited and monitored yearly. Our experimental design affords assessment of multisensory integration as a new behavioral marker for preclinical AD; identification of functional neural networks involved in the intersection of sensory, motor, and cognitive functioning; and determination of the impact of early AD on future mobility declines, including incident falls. Results of The VSI Study will guide future development of innovative multisensory-based interventions aimed at preventing disability and optimizing independence in pathological aging.

Risk factors for decline in gait speed during walking while talking in older adults.

BACKGROUND & AIMS: Slow gait speed during Walking While Talking (walking while reciting alternate letters of the alphabet; WWT) is associated with an increased risk of developing dementia and falls. The aim of this study was to examine longitudinal changes in WWT-speed and to identify risk factors that may modify the rate of change in WWT-speed. METHODS: A total of 431 older participants (55.7% female; M Age=76.8 ± 6.4 years; mean follow up 2.1 ± 1.8 years) enrolled in the Central Control of Mobility in Aging study were examined. WWT-speed (cm/s) was measured with a computerized walkway. The following baseline measures were examined as risk factors: demographics [age, sex, education], medical illnesses [hypertension, diabetes, cardiac arrhythmias, history of stroke, Parkinson's disease, kidney disease, arthritis], cognitive functions [global cognition, executive function, processing speed], physical and sensory functions [unipedal stance time, gait speed during single task walking, visual acuity], psychological variables [depression, anxiety] and falls. Linear mixed effect models were used to examine 1) change in WWT-speed over time, and 2) risk factors associated with change in WWT-speed over time. RESULTS: WWT-speed declined in an accelerating non-linear fashion over time after adjusting for baseline age, sex and education. The rate of decline in WWT-speed was modified by older age (b -0.16 95%CI -0.22, -0.09), poorer balance (b -1.73 95%CI -2.57, -0.90), and faster gait speed during single task walking (b -0.06 95%CI -0.08, -0.04). SIGNIFICANCE: This study identified fixed and modifiable risk factors of faster decline in WWT-speed over time in community-residing older adults.

Increased Social Support Reduces the Incidence of Motoric Cognitive Risk Syndrome.

Background and Objectives: The motoric cognitive risk syndrome (MCR) is a predementia syndrome characterized by slow gait and cognitive complaint. The relationship between MCR and social support-a potentially modifiable risk factor of dementia-is currently unknown. The current study aimed to determine whether MCR incidence varies as a function of social support in aging. Research Design and Methods: We examined MCR incidence in 506 community-dwelling older adults (M Age 76.59; 57.3% female) without MCR or dementia at baseline. We quantified perceived levels of social support with the Medical Outcomes Study Social Support Survey, incorporating four different categories of support: (a) emotional/informational support, (b) tangible support, (c) affectionate support, and (d) positive social interactions. We used Cox regression analyses, adjusted for age, sex, race/ethnicity, education, marital status, comorbidities, and global cognition, to estimate hazard ratios (aHR) with 95% confidence intervals (CIs). Results: Over a median follow-up time of 2.5 years (range = 1-7 years), 38 participants (9.8%) developed MCR. Increased tangible support decreased the risk of MCR by 30% (aHR: 0.70, 95% CI: 0.53-0.92, p = .011). Increased overall social support decreased the risk of MCR by 33% (aHR: 0.67, 95% CI: 0.46-0.98, p = .038). Other subcategories of social support were not associated with a decreased risk of MCR (p > .05). Discussion and Implications: Higher levels of tangible social support, as well as overall social support, were associated with reduced risk for MCR in older adults. Increasing social support may be a promising avenue of intervention for reducing the risk of MCR, dementia, and other forms of cognitive decline.