Michele L. Callisaya

Ageing and gait variability—a population-based study of older people

BACKGROUND gait variability may be an important predictor of falls risk, but its characteristics are poorly understood. OBJECTIVE to examine the relationship between age and gait variability in a population-based sample of older people. DESIGN cross-sectional study. METHODS in people aged 60-86 years (n = 412), temporal and spatial gait variability measures were recorded with a GAITRite walkway. Regression analysis was used to model the relationship between age and gait variability adjusting for height, weight and self-reported chronic disease. Further adjustment was made for gait speed to examine its influence on the associations. RESULTS older age was associated with greater variability (P < 0.05) in all gait measures. All relationships were linear, except that between age and step time variability, which was curvilinear in women. Adjusting for gait speed changed the magnitude of the age coefficient by 62-86% for temporal variability measures, 25% for step length variability and 5-12% for step width variability. CONCLUSION age is linearly associated with greater intra-individual gait variability for most gait measures, except for step time variability in women. Gait speed may mediate the association between age and temporal variability measures. Further study is needed to understand the factors responsible for the greater gait variability with ageing.

Cerebral White Matter Lesions, Gait, and the Risk of Incident Falls A Prospective Population-Based Study

Background and Purpose— The association between cerebral white matter lesions (WMLs) and the risk of falls in older people is uncertain, with no supporting prospective evidence. We aimed to determine the risk of incident falls associated with WML volume, and the interactions between WML volume, gait, and other sensorimotor factors leading to falls. Methods— We conducted a prospective, population-based study (n=294, mean age 72.3 years, independently mobile). Volumetric MRI, computerized gait measures, and sensorimotor measures of falls risk were obtained at baseline. Incident falls were recorded prospectively over a 12-month period. Using regression modeling, we estimated the risk of incident falls associated with baseline WML volume. Results— Increasing baseline WML volume was independently associated with any incident fall (P=0.01) and multiple incident falls (P=0.02). The risk of incident falls was doubled in people with lesion volumes in the highest quintile of its distribution compared with the lowest (adjusted relative risk, 2.32; 95% CI, 1.28–4.14). Greater lesion volume was also associated with poorer gait and greater gait variability (both P<0.001). The effect of WML volume on the risk of falls was magnified in people with poorer quadriceps muscle strength (P=0.03) and greater gait variability (P=0.001). Conclusions— These data provide the first prospective evidence to our knowledge demonstrating that WMLs are strong risk factors for falls in the general older population. WMLs present potential therapeutic targets for interventional trials in falls prevention.

Gait, gait variability and the risk of multiple incident falls in older people: a population-based study

BACKGROUND it is uncertain as to which measures of gait best predict those who are likely to fall. Our aim was to investigate the associations of gait and gait variability measures with incident falls risk. METHODS individuals aged 60-86 years (n = 412) were randomly selected from the Tasmanian electoral roll. Average gait and gait variability measures were collected on a computerised walkway. Falls were recorded prospectively over 12 months. Log multinomial regression was used to estimate the relative risk of single and multiple falls associated with gait measures. Covariates included age, sex, sensorimotor and cognitive measures, mood and medications. RESULTS in this population-based study greater intra-individual variability in step length and double-support phase were linearly associated with increased risk of multiple falls (P = 0.04). Non-linear associations with multiple falls were found for gait speed P = 0.002, cadence P = 0.004 and step time variability P = 0.03. None of the gait measures predicted risk of single falls. CONCLUSION there is an increased risk of multiple falls, but not single falls, in older people with poorer gait. Specific measures of gait and gait variability seem to confer this risk and may be amenable to interventions designed to reduce the risk of multiple falls in older people.

Motoric cognitive risk syndrome Multicountry prevalence and dementia risk

Objectives: Our objective is to report prevalence of motoric cognitive risk syndrome (MCR), a newly described predementia syndrome characterized by slow gait and cognitive complaints, in multiple countries, and its association with dementia risk. Methods: Pooled MCR prevalence analysis of individual data from 26,802 adults without dementia and disability aged 60 years and older from 22 cohorts from 17 countries. We also examined risk of incident cognitive impairment (Mini-Mental State Examination decline ≥4 points) and dementia associated with MCR in 4,812 individuals without dementia with baseline Mini-Mental State Examination scores ≥25 from 4 prospective cohort studies using Cox models adjusted for potential confounders. Results: At baseline, 2,808 of the 26,802 participants met MCR criteria. Pooled MCR prevalence was 9.7% (95% confidence interval [CI] 8.2%–11.2%). MCR prevalence was higher with older age but there were no sex differences. MCR predicted risk of developing incident cognitive impairment in the pooled sample (adjusted hazard ratio [aHR] 2.0, 95% CI 1.7–2.4); aHRs were 1.5 to 2.7 in the individual cohorts. MCR also predicted dementia in the pooled sample (aHR 1.9, 95% CI 1.5–2.3). The results persisted even after excluding participants with possible cognitive impairment, accounting for early dementia, and diagnostic overlap with other predementia syndromes. Conclusion: MCR is common in older adults, and is a strong and early risk factor for cognitive decline. This clinical approach can be easily applied to identify high-risk seniors in a wide variety of settings.

Cognitive Function, Gait, and Gait Variability in Older People: A Population-Based Study

BACKGROUND Gait impairments are associated with falls and loss of independence. The study of factors associated with poorer gait may assist in developing methods to preserve mobility in older people. The aim of this study was to examine the associations between a range of cognitive functions and gait and gait variability in a population-based sample of older people. METHODS Gait and intra-individual gait variability measures were obtained using the GAITRite walkway in a sample of older people, aged 60-85 years (N = 422), randomly selected from the Tasmanian electoral roll. Raw scores from a cognitive battery were subjected to principal component analyses deriving four summary domains: executive function/attention, processing speed, memory, and visuospatial ability. Multivariable linear regression was used to examine associations between cognitive domains and gait measures adjusting for age, sex, ambulatory activity, medication use, and mood. RESULTS The mean age of the sample was 72.0 years (SD = 7.0), with 238 men (56%). Poorer executive function was independently associated with poorer performance in most absolute gait measures and with greater variability in double support phase and step time. Processing speed was associated with absolute gait measures and double support phase variability. Visuospatial ability was only associated with greater double support phase variability, independently of executive function and processing speed. Memory was not independently associated with any gait measure. CONCLUSIONS In community-dwelling older people, executive function/attention and processing speed were associated with many aspects of gait, whereas visuospatial ability may only play a role in double support phase variability.

A population-based study of sensorimotor factors affecting gait in older people

BACKGROUND the study of factors associated with age-related gait decline may assist in developing methods to preserve mobility in older people. OBJECTIVE to examine the associations between sensorimotor factors relevant to ageing and gait in the general older population. DESIGN cross-sectional population-based study. METHODS participants aged 60-86 years (n = 278) were randomly selected using electoral roll sampling. Sensorimotor factors (quadriceps strength, reaction time, postural sway, proprioception and visual contrast sensitivity) were measured using the Physiological Profile Assessment. Gait variables (speed, cadence, step length, double support phase and step width) were recorded with a GAITRite walkway. Linear regression was used to model relationships between sensorimotor and gait variables. RESULTS mean age of participants was 72.4 (7.0) years with 154 (55%) males. Better quadriceps strength, reaction time and postural sway (in men) predicted faster gait speed due to their effects on step length and/or cadence. Body weight (in men) and visual contrast sensitivity (in women) were modifying factors in these relationships. Better postural sway, reaction time (in men) and quadriceps strength (in women) predicted reduced double support phase. Modifying factors were quadriceps strength (in men) and proprioception (in women). Postural sway was the sole predictor of step width and in women only. CONCLUSION potentially modifiable sensorimotor factors were associated with a range of gait measures, with a different pattern of individual associations and interactions seen between the sexes. These results provide further mechanistic insights towards explaining age-related gait decline in the general older population.

Type 2 diabetes mellitus and biomarkers of neurodegeneration

Objective: Our objective was to investigate whether type 2 diabetes mellitus (T2DM) influences neurodegeneration in a manner similar to Alzheimer disease (AD), by promoting brain β-amyloid (Aβ) or tau. Methods: We studied the cross-sectional associations of T2DM with cortical thickness, brain Aβ load, and CSF levels of Aβ and tau in a sample of people from the Alzheimers Disease Neuroimaging Initiative with diagnoses of AD dementia, mild cognitive impairment, and normal cognition. All (n = 816) received MRI, and a subsample underwent brain amyloid imaging (n = 102) and CSF Aβ and tau measurements (n = 415). Analyses were performed across and within cognitive diagnostic strata. Results: There were 124 people with T2DM (mean age 75.5 years) and 692 without T2DM (mean age 74.1 years). After adjusting for age, sex, total intracranial volume, APO ε4 status, and cognitive diagnosis, T2DM was associated with lower bilateral frontal and parietal cortical thickness (mL) (β = −0.03, p = 0.01). T2DM was not associated with 11C Pittsburgh compound B standardized uptake value ratio (AU) in any brain region or with CSF Aβ42 levels (pg/mL). T2DM was associated with greater CSF total tau (pg/mL) (β = 16.06, p = 0.04) and phosphorylated tau (β = 5.84, p = 0.02). The association between T2DM and cortical thickness was attenuated by 15% by the inclusion of phosphorylated tau. Conclusions: T2DM may promote neurodegeneration independent of AD dementia diagnosis, and its effect may be driven by tau phosphorylation. The mechanisms through which T2DM may promote tau phosphorylation deserve further study.

Brain structural change and gait decline: a longitudinal population-based study

To investigate longitudinal associations between changes in brain structure and gait decline.

Sensorimotor Factors Affecting Gait Variability in Older People—A Population-Based Study

BACKGROUND Intra-individual gait variability predicts falls and disability in older people. Knowledge of factors that contribute to gait variability may lead to interventions aimed at reducing decline in mobility and falls risk. The aim of this population-based study was to examine whether poorer performance on a range of sensorimotor measures was associated with greater gait variability. METHODS Individuals aged 60-86 years (n = 412) were randomly selected from the Southern Tasmanian electoral roll. Spatial (step length and step width) and temporal (step time and double support time [DST]) gait measures were recorded with a GAITRite walkway. Variability for each gait measure was the standard deviation of measurements recorded during six walks. Sensorimotor measures included visual contrast sensitivity, lower limb proprioception, quadriceps strength, reaction time, and body sway (eyes open and closed). Regression analysis was used to determine the relationships between sensorimotor measures and gait variability. RESULTS Greater sway on a foam mat (eyes closed) was associated with greater variability in all gait measures (p < .05). Slower reaction time was associated with greater variability in both temporal gait measures (p < .05), whereas poorer proprioception was only associated with greater DST variability (p = .01) and weaker quadriceps strength with greater step time variability. Other sensorimotor factors were not independently associated with gait variability. CONCLUSIONS Body sway, reaction time, quadriceps strength, and proprioception are likely factors that may explain gait variability in the general older population. Further research is warranted to determine causality of these associations and whether intervention programs addressing these factors may reduce gait variability in older people.

Risk of falls in older people during fast-walking--the TASCOG study.

AIMS To investigate the relationship between fast-walking and falls in older people. METHODS Individuals aged 60-86 years were randomly selected from the electoral roll (n=176). Gait speed, step length, cadence and a walk ratio were recorded during preferred- and fast-walking using an instrumented walkway. Falls were recorded prospectively over 12 months. Log multinomial regression was used to estimate the relative risk of single and multiple falls associated with gait variables during fast-walking and change between preferred- and fast-walking. Covariates included age, sex, mood, physical activity, sensorimotor and cognitive measures. RESULTS The risk of multiple falls was increased for those with a smaller walk ratio (shorter steps, faster cadence) during fast-walking (RR 0.92, CI 0.87, 0.97) and greater reduction in the walk ratio (smaller increase in step length, larger increase in cadence) when changing to fast-walking (RR 0.73, CI 0.63, 0.85). These gait patterns were associated with poorer physiological and cognitive function (p<0.05). A higher risk of multiple falls was also seen for those in the fastest quarter of gait speed (p=0.01) at fast-walking. A trend for better reaction time, balance, memory and physical activity for higher categories of gait speed was stronger for fallers than non-fallers (p<0.05). CONCLUSION Tests of fast-walking may be useful in identifying older individuals at risk of multiple falls. There may be two distinct groups at risk--the frail person with short shuffling steps, and the healthy person exposed to greater risk.