Mitnitski A.B.,Dalhousie University |
Mitnitski A.B.,Geriatric Medicine Research Unit |
Rutenberg A.D.,Dalhousie University |
Farrell S.,Dalhousie University |
And 2 more authors.
Biogerontology | Year: 2017
When people age their mortality rate increases exponentially, following Gompertz’s law. Even so, individuals do not die from old age. Instead, they accumulate age-related illnesses and conditions and so become increasingly vulnerable to death from various external and internal stressors. As a measure of such vulnerability, frailty can be quantified using the frailty index (FI). Larger values of the FI are strongly associated with mortality and other adverse health outcomes. This association, and the insensitivity of the FI to the particular health variables that are included in its construction, makes it a powerful, convenient, and increasingly popular integrative health measure. Still, little is known about why the FI works so well. Our group has recently developed a theoretical network model of health deficits to better understand how changes in health are captured by the FI. In our model, health-related variables are represented by the nodes of a complex network. The network has a scale-free shape or “topology”: a few nodes have many connections with other nodes, whereas most nodes have few connections. These nodes can be in two states, either damaged or undamaged. Transitions between damaged and non-damaged states are governed by the stochastic environment of individual nodes. Changes in the degree of damage of connected nodes change the local environment and make further damage more likely. Our model shows how age-dependent acceleration of the FI and of mortality emerges, even without specifying an age-damage relationship or any other time-dependent parameter. We have also used our model to assess how informative individual deficits are with respect to mortality. We find that the information is larger for nodes that are well connected than for nodes that are not. The model supports the idea that aging occurs as an emergent phenomenon, and not as a result of age-specific programming. Instead, aging reflects how damage propagates through a complex network of interconnected elements. © 2017 Springer Science+Business Media Dordrecht
Armstrong J.J.,Dalhousie University |
Godin J.,Geriatric Medicine Research Unit |
Launer L.J.,U.S. National Institute on Aging |
White L.R.,Pacific Health Research and Education Institute |
And 4 more authors.
Journal of Alzheimer's Disease | Year: 2016
Background: As cognitive decline mostly occurs in late life, where typically it co-exists with many other ailments, it is important to consider frailty in understanding cognitive change. Objective: Here, we examined the association of change in frailty status with cognitive trajectories in a well-studied cohort of older Japanese-American men. Methods: Using the prospective Honolulu-Asia Aging Study (HAAS), 2,817 men of Japanese descent were followed (aged 71-93 at baseline). Starting in 1991 with follow-up health assessments every two to three years, cognition was measured using the Cognitive Abilities Screening Instrument (CASI). For this study, health data was used to construct an accumulation of deficits frailty index (FI). Using six waves of data, multilevel growth curve analyses were constructed to examine simultaneous changes in cognition in relation to changes in FI, controlling for baseline frailty, age, education, and APOE-ϵ4 status. Results: On average, CASI scores declined by 2.0 points per year (95 confidence interval 1.9-2.1). Across six waves, each 10 within-person increase in frailty from baseline was associated with a 5.0 point reduction in CASI scores (95 confidence interval 4.7-5.2). Baseline frailty and age were associated both with lower initial CASI scores and with greater decline across the five follow-up assessments (p<0.01). Discussion: Cognition is adversely affected by impaired health status in old age. Using a multidimensional measure of frailty, both baseline status and within-person changes in frailty were predictive of cognitive trajectories. © 2016 - IOS Press and the authors. All rights reserved.
PubMed | U.S. National Institute on Aging, Pacific Health Research & Education Institute, Geriatric Medicine Research Unit and Dalhousie University
Type: Journal Article | Journal: Journal of Alzheimer's disease : JAD | Year: 2016
As cognitive decline mostly occurs in late life, where typically it co-exists with many other ailments, it is important to consider frailty in understanding cognitive change.Here, we examined the association of change in frailty status with cognitive trajectories in a well-studied cohort of older Japanese-American men.Using the prospective Honolulu-Asia Aging Study (HAAS), 2,817 men of Japanese descent were followed (aged 71-93 at baseline). Starting in 1991 with follow-up health assessments every two to three years, cognition was measured using the Cognitive Abilities Screening Instrument (CASI). For this study, health data was used to construct an accumulation of deficits frailty index (FI). Using six waves of data, multilevel growth curve analyses were constructed to examine simultaneous changes in cognition in relation to changes in FI, controlling for baseline frailty, age, education, and APOE-4 status.On average, CASI scores declined by 2.0 points per year (95% confidence interval 1.9-2.1). Across six waves, each 10% within-person increase in frailty from baseline was associated with a 5.0 point reduction in CASI scores (95% confidence interval 4.7-5.2). Baseline frailty and age were associated both with lower initial CASI scores and with greater decline across the five follow-up assessments (p<0.01).Cognition is adversely affected by impaired health status in old age. Using a multidimensional measure of frailty, both baseline status and within-person changes in frailty were predictive of cognitive trajectories.
Mitnitski A.,Dalhousie University |
Fallah N.,Geriatric Medicine Research Unit |
Rockwood M.R.H.,Geriatric Medicine Research Unit |
Rockwood K.,Dalhousie University
Journal of Nutrition, Health and Aging | Year: 2011
Objectives: Cognitive decline is related to frailty. Frailty can be operationalized in different ways, which have an unknown impact on the estimation of risk. Here, we compared 3 frailty measures in relation to cognitive changes and mortality in the Canadian Study of Health and Aging (CSHA). Design: Prospective population-based study, with 5 year follow up. Participants/Setting: 2,305 subjects aged 70+ years. Methods: For each participant, cognitive status was measured by the errors in the Modified Mini-Mental State Examination (3MS) score. Three frailty measures were used: a Frailty Index based on the Comprehensive Geriatric Assessment (FI-CGA) evaluated from 47 potential deficits, a Clinical Frailty Score and the Fried frailty phenotype. Multivariate Poisson regression and multivariate logistic regression were used to examine the association between baseline cognitive errors and frailty and death, respectively, while controlling for possible confounders (age, sex, education, and baseline cognitive status). Results: Changes in cognitive status were strongly associated with baseline cognition and frailty, however defined. In multivariate models adjusted for age, sex and education, each frailty measure was associated with cognitive decline and with mortality. The frailest people (from the highest FI-CGA tertile) rarely showed cognitive improvement or stabilization (1.5%, 95% CI=0.002%-2.8%) compared with non-frail people (from the lowest tertile of the FI-CGA), of whom 27.8% (95% CI=24.5%-31.1%) did not deteriorate. Conclusions: Frail elderly people have an increased risk of cognitive decline. All frailty measures allowed quantification of individual vulnerability and predict both cognitive changes and mortality. © 2011 Serdi and Springer Verlag France.
Shi J.,Beijing Hospital |
Shi J.,Geriatric Medicine Research Unit |
Yang Z.,Geriatric Medicine Research Unit |
Yang Z.,Crandall University |
And 9 more authors.
Journals of Gerontology - Series A Biological Sciences and Medical Sciences | Year: 2014
Background. On average, as people age, they accumulate more health deficits and have an increased risk of death. The deficit accumulation-based frailty index (FI) can quantify health and its outcomes in aging. Previous studies have suggested that women show higher FI values than men and that the highest FI score (the limit to frailty) occurs at a value of FI ~ 0.7. Even so, gender differences in the limit to frailty have not been reported. Methods. Data for this analysis were obtained from the Beijing Longitudinal Study of Aging that involved 3,257 community-dwelling Chinese people, aged 55+ years at baseline. The main outcome measure was 5-year mortality. An FI consisting of 35 health-related variables was constructed. The absolute and 99% FI limits were calculated for different age groups and analyzed by sex. Results. The mean level of the FI increased with age and was lower in men than in women (F = 67.87, p <. 001). The 99% FI limit leveled off slightly earlier with a relatively lower value in men (60 years; 0.44 ± 0.02) compared with that in women (65 years; 0.52 ± 0.04). The highest absolute FI value was 0.61 in men and 0.69 in women. In both groups, people with an FI greater than or equal to the 99% limit showed close to 100% mortality by 5 years. Conclusion. Compared with men, women appeared to better tolerate deficits in health, yielding both relatively lower mortality and higher limit values to the FI. Even so, the FI did not exceed 0.7 in any individual. © 2013 The Author.
PubMed | Geriatric Medicine Research Unit and Dalhousie University
Type: Journal Article | Journal: Canadian geriatrics journal : CGJ | Year: 2016
Frail older adults present to the Emergency Department (ED) with complex medical, functional, and social needs. When these needs can be addressed promptly, discharge is possible, and when they cannot, hospital admission is required. We evaluated the care needs of frail older adults in the ED who were consulted to internal medicine and seen by a geriatrician to determine, under current practices, which factors were associated with hospitalization and which allowed discharge.We preformed a chart-based, exploratory study. Data were abstracted from consultation records and ED charts. All cases had a standard Comprehensive Geriatric Assessment (CGA which records a Clinical Frailty Scale (CFA) and allows calculation of a Frailty Index (FI).Of 100 consecutive patients, 2 died in the ED, 75 were admitted, and 23 were discharged, including one urgent placement. Compared with discharged patients (0.39 SD 0.16), those admitted had a higher mean FI-CGA (0.48 0.13; p < .01). Greater mobility dependence (2% in discharged vs. 32% in admitted; p < .05) was notable.Discharge decisions require assessment of medical, functional, and social problems. Ill, frail patients often can be discharged home when social and nursing support can be provided. The degree of frailty, impaired mobility, and likely delirium must be taken into account when planning for their care.
PubMed | Geriatric Medicine Research Unit
Type: Journal Article | Journal: The journals of gerontology. Series A, Biological sciences and medical sciences | Year: 2010
Frailty has been conceptualized as a wasting disorder with weight loss as a key component. However, obesity is associated with disability and with physiological markers also recently linked with frailty, for example, increased inflammation and low antioxidant capacity. We aimed to explore the relationship between frailty and body mass index (BMI) in older people.Data were from 3,055 community-dwelling adults aged 65 years and older who participated in the English Longitudinal Study of Ageing. Frailty was defined both by an index of accumulated deficits and by the Fried phenotype. BMI was divided into five categories, and waist circumference 88 cm or more (for women) and 102 cm or more (for men) was defined as high. Analyses were adjusted for sex, age, wealth, level of education, and smoking status.The association between BMI and frailty showed a U-shaped curve. This relationship was consistent across different frailty measures. The lowest frailty index (FI) scores and lowest prevalence of Fried frailty were in those with BMI 25-29.9. At each BMI category, and using either measure of frailty, those with a high waist circumference were significantly more frail.Both the phenotypic definition of frailty and the FI show increased levels of frailty among those with low and very high BMIs. In view of the rise in obesity in older populations, the benefits and feasibility of diet and exercise for obese older adults should be a focus of urgent inquiries. The association of frailty with a high waist circumference, even among underweight older people, suggests that truncal obesity may be an additional target for intervention.