@article {6000, title = {Do changes in circulating biomarkers track with each other and with functional changes in older adults?}, journal = {J Gerontol A Biol Sci Med Sci}, volume = {69}, year = {2014}, month = {2014 Feb}, pages = {174-81}, abstract = {

BACKGROUND: It is unclear if changes in proposed circulating biomarkers of aging are strongly correlated to each other or functional change. We tested if biomarker changes track with each other and with functional measures over 9 years in older adults.

METHODS: Dehydroepiandrosterone sulfate (DHEAS), adiponectin, insulin-like growth factor 1 (IGF-1), IGF binding proteins 1 (IGFBP-1) and 3 (IGFBP-3), interleukin-6 (IL-6), cholesterol, and function (gait speed, grip strength, Modified Mini Mental Status Exam [3MSE] and Digit Symbol Substitution Test [DSST] scores) were measured in 1996-1997 and 2005-2006 in the Cardiovascular Health Study All Stars study (N = 901, mean [standard deviation, SD] age 85.3 [3.6] years in 2005-2006). Adjusted Pearson correlations illustrated if biomarkers tracked together. Multivariable linear regression demonstrated if biomarker changes tracked with functional changes.

RESULTS: Correlations among biomarker changes were mostly <0.2. In models with each biomarker entered separately, a 1-SD increase biomarker change was associated with change in function as follows: grip strength (DHEAS β = 0.61kg, p = .001; IL-6 β = -0.46kg, p = .012; cholesterol men β = 0.79kg, p = .016); gait speed (DHEAS β = 0.02 meters per second, p = .039; IL-6 β = -0.018 meters per second, p = .049); and DSST score (DHEAS women β = 1.46, p = .004; IL-6 β = -0.83, p = .027). When biomarkers were entered in the same model, significant associations remaining were as follows: grip strength (DHEAS β = 0.54kg, p = .005; IL-6 β = -0.43kg, p = .022); 3MSE score (IGF-1 β = 0.96, p = .04; IGFBP-3 β = -1.07, p = .024); and DSST score (DHEAS women β = 1.27, p = .012; IL-6 β = -0.80, p = .04).

CONCLUSION: Changes in biomarkers were poorly correlated, supporting a model of stochastic, independent change across systems. DHEAS and IL-6 tracked most closely with function, illustrating that changes in inflammation and sex steroids may play dominant roles in changes of these functional outcomes.

}, keywords = {Adiponectin, Aged, Aged, 80 and over, Aging, Biomarkers, Cholesterol, Cognition, Cohort Studies, Dehydroepiandrosterone Sulfate, Female, Gait, Hand Strength, Humans, Insulin-Like Growth Factor Binding Protein 1, Insulin-Like Growth Factor Binding Protein 3, Insulin-Like Growth Factor I, Interleukin-6, Male, Neuropsychological Tests, Psychomotor Performance, Time Factors}, issn = {1758-535X}, doi = {10.1093/gerona/glt088}, author = {Sanders, Jason L and Ding, Victoria and Arnold, Alice M and Kaplan, Robert C and Cappola, Anne R and Kizer, Jorge R and Boudreau, Robert M and Cushman, Mary and Newman, Anne B} } @article {6596, title = {Multisystem physiologic impairments and changes in gait speed of older adults.}, journal = {J Gerontol A Biol Sci Med Sci}, volume = {70}, year = {2015}, month = {2015 Mar}, pages = {319-24}, abstract = {

BACKGROUND: Slowed gait is an important health indicator in older adults but a single identifiable cause is often lacking. We assessed whether a summary index measuring impairments across multiple physiologic systems was associated with slowed gait in older individuals.

METHODS: Data from the Cardiovascular Health Study (n = 3,010) were used to assess associations between baseline physiologic index (measuring vasculature, brain, kidneys, lungs, and glucose metabolism; range 0-10 with 0-2 points/system and lower score indicating higher function) and annual gait speed (m/s) over 6 years. Participants with complete data on the physiologic index and at least two gait speed measures were included. Mean gait speed and 95\% confidence intervals (CI) by category of index were calculated using mixed effects models.

RESULTS: Those with scores of three or higher on the index had significantly slower gait speed at baseline compared to those with scores of 0-2 (7-10: mean speed = 0.83 m/s, 95\% CI: 0.80, 0.84; 0-2: mean speed = 1.01 m/s, 95\% CI: 0.99, 1.03). Those with higher indices also had faster decline in gait speed compared to those with lower scores after adjustment for demographic and health characteristics (7-10: change in speed = -0.020 m/s/year, 95\% CI: -0.024, -0.016; 0-2: change in speed= -0.010 m/s/year, 95\% CI: -0.014, -0.006).

CONCLUSIONS: Greater impairment across five organ systems was associated with slower gait speed and greater declines in gait speed over 6 years. Impairments accumulated over multiple physiologic systems may make older adults more vulnerable to slow gait speed.

}, keywords = {Age Factors, Aged, Aged, 80 and over, Brain, Cardiovascular Physiological Phenomena, Cohort Studies, Female, Gait, Geriatric Assessment, Glucose, Health Status Indicators, Humans, Kidney, Lung, Male, Sensitivity and Specificity, Time Factors}, issn = {1758-535X}, doi = {10.1093/gerona/glu176}, author = {Rosso, Andrea L and Sanders, Jason L and Arnold, Alice M and Boudreau, Robert M and Hirsch, Calvin H and Carlson, Michelle C and Rosano, Caterina and Kritchevsky, Stephen B and Newman, Anne B} }