Caterina Rosano

Gait Speed and Survival in Older Adults

CONTEXT Survival estimates help individualize goals of care for geriatric patients, but life tables fail to account for the great variability in survival. Physical performance measures, such as gait speed, might help account for variability, allowing clinicians to make more individualized estimates. OBJECTIVE To evaluate the relationship between gait speed and survival. DESIGN, SETTING, AND PARTICIPANTS Pooled analysis of 9 cohort studies (collected between 1986 and 2000), using individual data from 34,485 community-dwelling older adults aged 65 years or older with baseline gait speed data, followed up for 6 to 21 years. Participants were a mean (SD) age of 73.5 (5.9) years; 59.6%, women; and 79.8%, white; and had a mean (SD) gait speed of 0.92 (0.27) m/s. MAIN OUTCOME MEASURES Survival rates and life expectancy. RESULTS There were 17,528 deaths; the overall 5-year survival rate was 84.8% (confidence interval [CI], 79.6%-88.8%) and 10-year survival rate was 59.7% (95% CI, 46.5%-70.6%). Gait speed was associated with survival in all studies (pooled hazard ratio per 0.1 m/s, 0.88; 95% CI, 0.87-0.90; P < .001). Survival increased across the full range of gait speeds, with significant increments per 0.1 m/s. At age 75, predicted 10-year survival across the range of gait speeds ranged from 19% to 87% in men and from 35% to 91% in women. Predicted survival based on age, sex, and gait speed was as accurate as predicted based on age, sex, use of mobility aids, and self-reported function or as age, sex, chronic conditions, smoking history, blood pressure, body mass index, and hospitalization. CONCLUSION In this pooled analysis of individual data from 9 selected cohorts, gait speed was associated with survival in older adults.

Physical activity predicts gray matter volume in late adulthood The Cardiovascular Health Study

Objectives: Physical activity (PA) has been hypothesized to spare gray matter volume in late adulthood, but longitudinal data testing an association has been lacking. Here we tested whether PA would be associated with greater gray matter volume after a 9-year follow-up, a threshold could be identified for the amount of walking necessary to spare gray matter volume, and greater gray matter volume associated with PA would be associated with a reduced risk for cognitive impairment 13 years after the PA evaluation. Methods: In 299 adults (mean age 78 years) from the Cardiovascular Health Cognition Study, we examined the association between gray matter volume, PA, and cognitive impairment. Physical activity was quantified as the number of blocks walked over 1 week. High-resolution brain scans were acquired 9 years after the PA assessment on cognitively normal adults. White matter hyperintensities, ventricular grade, and other health variables at baseline were used as covariates. Clinical adjudication for cognitive impairment occurred 13 years after baseline. Results: Walking amounts ranged from 0 to 300 blocks (mean 56.3; SD 69.7). Greater PA predicted greater volumes of frontal, occipital, entorhinal, and hippocampal regions 9 years later. Walking 72 blocks was necessary to detect increased gray matter volume but walking more than 72 blocks did not spare additional volume. Greater gray matter volume with PA reduced the risk for cognitive impairment 2-fold. Conclusion: Greater amounts of walking are associated with greater gray matter volume, which is in turn associated with a reduced risk of cognitive impairment.

Limited Literacy in Older People and Disparities in Health and Healthcare Access

OBJECTIVES: To determine the relationship between health literacy, demographics, and access to health care.

Association between Physical and Cognitive Function in Healthy Elderly: The Health, Aging and Body Composition Study

Performance measures of physical function (gait speed, chair stands, standing balance) and cognitive function [Teng-modified Mini-Mental Status Exam (3MS) and digit symbol substitution test (DSST)] were assessed at baseline in 3,075 participants in the Health, Aging and Body Composition Study. Each physical function measure was examined for the strength and magnitude of association with cognitive function. All physical function measures were associated with both the 3MS and DSST scores (p < 0.001), and in multivariate analysis each relationship was independent of demographic characteristics, weight, physical activity and comorbid health conditions of participants. The association of motor performance was consistently greater for the DSST than the 3MS and, among the motor tests, gait speed retained a significant association with both cognitive measures independent of demographic, weight, physical activity and comorbid health conditions. In this large cohort of high-functioning older adults, the correlation between physical and cognitive function was not entirely explained by demographics. Longitudinal studies are needed to determine the direction of causality in this relationship.

Subclinical brain magnetic resonance imaging abnormalities predict physical functional decline in high-functioning older adults

Objectives: To determine whether severity of subclinical brain magnetic resonance imaging (MRI) abnormalities predicts incident self‐reported physical impairment or rate of decline in motor performance.

Diabetes, Glucose Control, and 9-Year Cognitive Decline Among Older Adults Without Dementia

OBJECTIVES To determine if prevalent and incident diabetes mellitus (DM) increase risk of cognitive decline and if, among elderly adults with DM, poor glucose control is related to worse cognitive performance. DESIGN Prospective cohort study. SETTING Health, Aging, and Body Composition Study at 2 community clinics. PARTICIPANTS A total of 3069 elderly adults (mean age, 74.2 years; 42% black; 52% female). MAIN OUTCOME MEASURES Participants completed the Modified Mini-Mental State Examination (3MS) and Digit Symbol Substitution Test (DSST) at baseline and selected intervals over 10 years. Diabetes mellitus status was determined at baseline and during follow-up visits. Glycosylated hemoglobin A1c level was measured at years 1 (baseline), 4, 6, and 10 from fasting whole blood. RESULTS At baseline, 717 participants (23.4%) had prevalent DM and 2352 (76.6%) were without DM, 159 of whom developed incident DM during follow-up. Participants with prevalent DM had lower baseline test scores than participants without DM (3MS: 88.8 vs 90.9; DSST: 32.5 vs 36.3, respectively; t = 6.09; P = .001 for both tests). Results from mixed-effects models showed a similar pattern for 9-year decline (3MS: -6.0- vs -4.5-point decline; t = 2.66; P = .008; DSST: -7.9- vs -5.7-point decline; t = 3.69; P = .001, respectively). Participants with incident DM tended to have baseline and 9-year decline scores between the other 2 groups but were not statistically different from the group without DM. Multivariate adjustment for demographics and medical comorbidities produced similar results. Among participants with prevalent DM, glycosylated hemoglobin A1c level was associated with lower average mean cognitive scores (3MS: F = 8.2; P for overall = .003; DSST: F = 3.4; P for overall = .04), even after multivariate adjustment. CONCLUSION Among well-functioning older adults, DM and poor glucose control among those with DM are associated with worse cognitive function and greater decline. This suggests that severity of DM may contribute to accelerated cognitive aging.

Quantitative Measures of Gait Characteristics Indicate Prevalence of Underlying Subclinical Structural Brain Abnormalities in High-Functioning Older Adults

Abnormal gait in high-functioning older adults may indicate underlying subtle structural brain abnormalities. We tested the hypothesis that temporal and spatial parameters of gait, including speed, stride length and double support time, are cross-sectionally associated with white matter hyperintensity, subcortical infarcts or brain atrophy on brain MRI. We examined 321 men and women (mean age = 78.3) participating to the Cardiovascular Health Study who were free of dementia or stroke at the time of the gait assessment. Analyses were set with gait as independent variable and brain MRIs as dependent variables. Gait measures were determined from the footfalls recorded on a 4-meter-long instrumented walking surface, the GaitMat II. Brain MRIs were examined for the presence of white matter hyperintensity (WMG, graded from 0 to 9), brain infarcts (predominantly subcortical) and ventricular enlargement (graded from 0 to 9). Slower gait, shorter stride length and longer double support times were associated with greater prevalence of white matter grade ≧3 (p = 0.02), and at least 1 brain infarct (p = 0.04) independent of age. In multivariate logistic regression models adjusted for demographics and clinical cardiovascular diseases, those with gait speed <1.02 m/s were more likely to have WMG ≧3 and at least 1 brain infarct, compared with those with faster gait – odds ratio (OR): 2.85, 95% confidence interval (95% CI): 1.35, 6.02, and OR: 2.09, 95% CI: 1.04, 4.19. Shorter stride length was also associated with greater probability of having at least 1 brain infarct (gait stride <0.88 vs. >1.10 m: OR: 3.20, 95% CI: 1.49, 6.88), while longer double support times were associated with a greater probability of having WMG ≧3 (double support time >0.19 vs. <0.14 s: OR: 2.3, 95% CI: 1.1, 4.7) independent of demographics and clinical cardiovascular diseases. Gait parameters were not significantly associated with ventricular grade. In summary, in this group of high-functioning older adults, poorer gait speed, shorter stride and longer double support time are associated with high white matter disease and subclinical strokes.

Executive Function, Memory, and Gait Speed Decline in Well-Functioning Older Adults

BACKGROUND In community-dwelling older adults, global cognitive function predicts longitudinal gait speed decline. Few prospective studies have evaluated whether specific executive cognitive deficits in aging may account for gait slowing over time. METHODS Multiple cognitive tasks were administered at baseline in 909 participants in the Health, Aging, and Body Composition Study Cognitive Vitality Substudy (mean age 75.2 ± 2.8 years, 50.6% women, 48.4% black). Usual gait speed (m/s) over 20 minutes was assessed at baseline and over a 5-year follow-up. RESULTS Poorer performance in each cognitive task was cross-sectionally associated with slower gait independent of demographic and health characteristics. In longitudinal analyses, each 1 SD poorer performance in global function, verbal memory, and executive function was associated with 0.003-0.004 m/s greater gait speed decline per year (p =.03-.05) after adjustment for baseline gait speed, demographic, and health characteristics. CONCLUSIONS In this well-functioning cohort, several cognitive tasks were associated with gait speed cross-sectionally and predicted longitudinal gait speed decline. These data are consistent with a shared pathology underlying cognitive and motor declines but do not suggest that specific executive cognitive deficits account for slowing of usual gait in aging.

Gait Variability Is Associated with Subclinical Brain Vascular Abnormalities in High-Functioning Older Adults

Background: Gait variability is an index of how much gait parameters, such as step length, change from one step to the next. Gait variability increases with age and in individuals affected by cortical and subcortical neurodegenerative conditions, and it is associated with falls and incident mobility disability. The brain anatomical correlates of gait variability have not been studied in high-functioning community-dwelling older adults. Methods: Gait variability and brain MRIs were assessed in a cohort of 331 men and women (mean age = 78.3 years) free from stroke, dementia or Parkinson’s disease. Gait variability was computed for spatial parameters (step length and step width) and for temporal parameters (stance time). Subclinical brain vascular abnormalities were measured on brain MRIs as infarcts and white matter hyperintensities. Results: Greater variability of step length was associated with greater prevalence of infarcts, including infarcts in the basal ganglia, and with greater white matter hyperintensities severity, independent of age, gender, cognitive function and cardiovascular disease. Weaker associations were found between the other variability measures and the MRI measures. Conclusion: In this group of older adults free from neurodegenerative diseases, a greater variability of step length was associated with greater burden of subclinical brain vascular abnormalities as defined by MRI.

Serum leptin level and cognition in the elderly: Findings from the Health ABC Study

Leptin is a peptide hormone secreted by adipocytes. It has been shown to modulate production and clearance of amyloid beta (Abeta) in rodent models. We sought to determine if serum leptin was associated with cognitive decline in the elderly. We studied 2871 well-functioning elders, aged 70-79, who were enrolled in a prospective study. Serum leptin concentrations were measured at baseline and analyzed by mean+/-1S.D. Clinically significantly cognitive decline over 4 years was defined as > or =5-point drop on the Modified Mini Mental State Exam (3MS). Compared to those in the lower leptin groups, elders in the high leptin group had less cognitive decline, 20.5% versus 24.7% (OR=0.79; 95% CI 0.61-1.02, p=0.07). After adjustment for demographic and clinical variables, including body mass index and total percent body fat, those in the high leptin group had significantly less likelihood of cognitive decline, OR=0.66 (95% CI 0.48-0.91). We conclude that in elderly individuals, higher serum leptin appears to protect against cognitive decline, independent of comorbidites and body fat.