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Farrell S, Kane AE, Bisset E, Howlett SE, Rutenberg AD. Measurements of damage and repair of binary health attributes in aging mice and humans reveal that robustness and resilience decrease with age, operate over broad timescales, and are affected differently by interventions. eLife 2022; 11:e77632. [PMID: 36409200 PMCID: PMC9725749 DOI: 10.7554/elife.77632] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/05/2022] [Accepted: 11/20/2022] [Indexed: 11/23/2022] Open
Abstract
As an organism ages, its health-state is determined by a balance between the processes of damage and repair. Measuring these processes requires longitudinal data. We extract damage and repair transition rates from repeated observations of binary health attributes in mice and humans to explore robustness and resilience, which respectively represent resisting or recovering from damage. We assess differences in robustness and resilience using changes in damage rates and repair rates of binary health attributes. We find a conserved decline with age in robustness and resilience in mice and humans, implying that both contribute to worsening aging health - as assessed by the frailty index (FI). A decline in robustness, however, has a greater effect than a decline in resilience on the accelerated increase of the FI with age, and a greater association with reduced survival. We also find that deficits are damaged and repaired over a wide range of timescales ranging from the shortest measurement scales toward organismal lifetime timescales. We explore the effect of systemic interventions that have been shown to improve health, including the angiotensin-converting enzyme inhibitor enalapril and voluntary exercise for mice. We have also explored the correlations with household wealth for humans. We find that these interventions and factors affect both damage and repair rates, and hence robustness and resilience, in age and sex-dependent manners.
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Affiliation(s)
| | - Alice E Kane
- Blavatnik Institute, Department of Genetics, Paul F. Glenn Center for Biology of Aging Research at Harvard Medical SchoolBostonUnited States
| | - Elise Bisset
- Department of Pharmacology, Dalhousie UniversityHalifaxCanada
| | - Susan E Howlett
- Department of Pharmacology, Dalhousie UniversityHalifaxCanada
- Department of Medicine (GeriatricMedicine), Dalhousie UniversityHalifaxCanada
| | - Andrew D Rutenberg
- Department of Physics and Atmospheric Science, Dalhousie UniversityHalifaxCanada
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Armstrong JJ, Godin J, Launer LJ, White LR, Mitnitski A, Rockwood K, Andrew MK. Changes in Frailty Predict Changes in Cognition in Older Men: The Honolulu-Asia Aging Study. J Alzheimers Dis 2016; 53:1003-13. [PMID: 27314525 PMCID: PMC5469372 DOI: 10.3233/jad-151172] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023]
Abstract
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-ɛ4 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.
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Affiliation(s)
- Joshua J Armstrong
- Geriatric Medicine Research Unit, Department of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Judith Godin
- Geriatric Medicine Research Unit, Nova Scotia Health Authority, Halifax, NS, Canada
| | - Lenore J Launer
- Laboratory of Epidemiology and Population Sciences, National Institute on Aging, Bethesda, MD, USA
| | - Lon R White
- Pacific Health Research & Education Institute, Honolulu, Hawaii, USA
| | - Arnold Mitnitski
- Geriatric Medicine Research Unit, Department of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Kenneth Rockwood
- Geriatric Medicine Research Unit, Department of Medicine, Dalhousie University, Halifax, NS, Canada
| | - Melissa K Andrew
- Geriatric Medicine Research Unit, Department of Medicine, Dalhousie University, Halifax, NS, Canada
- Geriatric Medicine Research Unit, Nova Scotia Health Authority, Halifax, NS, Canada
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Armstrong JJ, Mitnitski A, Andrew MK, Launer LJ, White LR, Rockwood K. Cumulative impact of health deficits, social vulnerabilities, and protective factors on cognitive dynamics in late life: a multistate modeling approach. ALZHEIMERS RESEARCH & THERAPY 2015; 7:38. [PMID: 26052349 PMCID: PMC4457088 DOI: 10.1186/s13195-015-0120-7] [Citation(s) in RCA: 32] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 01/06/2015] [Accepted: 03/16/2015] [Indexed: 01/03/2023]
Abstract
Introduction Many factors influence late-life cognitive changes, and evaluating their joint impact is challenging. Typical approaches focus on average decline and a small number of factors. We used multistate transition models and index variables to look at changes in cognition in relation to frailty (accumulation of health deficits), social vulnerability, and protective factors in the Honolulu-Asia Aging Study (HAAS). Methods The HAAS is a prospective cohort study of 3,845 men of Japanese descent, aged 71 to 93 years at baseline. Cognitive function was measured using the Cognitive Abilities Screening Instrument (CASI). Baseline index variables were constructed of health deficits (frailty), social vulnerabilities, and protective factors. The chances of improvement/stability/decline in cognitive function and death were simultaneously estimated using multistate transition modeling for 3- and 6-year transitions from baseline. Results On average, CASI scores declined by 5.3 points (standard deviation (SD) = 10.0) over 3 years and 9.5 points (SD = 13.9) over 6 years. After adjusting for education and age, baseline frailty was associated with an increased risk of cognitive decline at 3 years (β = 0.18, 95% confidence interval (CI), 0.08 to 0.29) and 6 years (β = 0.40, 95% CI, 0.27 to 0.54). The social vulnerability index was associated with 3-year changes (β = 0.16, 95% CI, 0.09 to 0.23) and 6-year changes (β = 0.14, 95% CI, 0.05 to 0.24) in CASI scores. The protective index was associated with reductions in cognitive decline over the two intervals (3-year: β = −0.16, 95% CI, −0.24 to −0.09; 6-year: β = −0.21, 95% CI, −0.31 to –0.11,). Conclusions Research on cognition in late life needs to consider overall health, the accumulation of protective factors, and the dynamics of cognitive change. Index variables and multistate transition models can enhance understanding of the multifactorial nature of late-life changes in cognition. Electronic supplementary material The online version of this article (doi:10.1186/s13195-015-0120-7) contains supplementary material, which is available to authorized users.
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Affiliation(s)
- Joshua J Armstrong
- Geriatric Medicine Research, Faculty of Medicine, Dalhousie University, Halifax, NS Canada
| | - Arnold Mitnitski
- Geriatric Medicine Research, Faculty of Medicine, Dalhousie University, Halifax, NS Canada
| | - Melissa K Andrew
- Geriatric Medicine Research, Faculty of Medicine, Dalhousie University, Halifax, NS Canada ; Department of Medicine, Division of Geriatric Medicine, Dalhousie University, Halifax, NS Canada
| | - Lenore J Launer
- Laboratory of Epidemiology, Demography, and Biometry, National Institute on Aging, Bethesda, MD USA
| | - Lon R White
- Pacific Health Research & Education Institute, Honolulu, HI USA
| | - Kenneth Rockwood
- Geriatric Medicine Research, Faculty of Medicine, Dalhousie University, Halifax, NS Canada ; Department of Medicine, Division of Geriatric Medicine, Dalhousie University, Halifax, NS Canada
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Engler D, Chitnis T, Healy B. Joint assessment of dependent discrete disease state processes. Stat Methods Med Res 2015; 26:1182-1198. [DOI: 10.1177/0962280215569899] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
Abstract
In multiple sclerosis, the primary clinical measure of disability level is an ordinal score, the expanded disability severity scale score. In relapsing-remitting multiple sclerosis, measures of relapse are additionally of interest. Multiple sclerosis patients are typically assessed with regard to both the expanded disability severity scale and relapse state at each follow-up visit. As both are discrete measures, the two can be viewed as jointly dependent Markov processes. One of the main goals of multiple sclerosis research is to accurately model, over time, both transitions between expanded disability severity scale states and change in relapse state. This objective requires a number of significant modeling decisions, including decisions about whether or not the combination of specific disease states is warranted and assessment of the dependence structure between the two disease processes. Historically, such decisions are often made in an ad hoc manner and are not formally justified. We propose novel use of Bayes factors and Bayesian variable selection in the assessment of jointly dependent Markovian processes in multiple sclerosis. Methods are assessed using both simulated data and data collected from the Partners Multiple Sclerosis Center in Boston, MA.
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Affiliation(s)
- David Engler
- Department of Statistics, Brigham Young University, Provo, USA
| | - Tanuja Chitnis
- Partners MS Center, Brigham and Women’s Hospital, Brookline, USA
| | - Brian Healy
- Biostatistics Center, Massachusetts General Hospital, Boston, USA
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Abstract
BACKGROUND Despite its importance in the lived experience of dementia, symptom fluctuation has been little studied outside Lewy body dementia. We aimed to characterize symptom fluctuation in patients with Alzheimer's disease (AD) and mixed dementia. METHODS A qualitative analysis of health records that included notations on good days and bad days yielded 52 community-dwelling patients (women, n = 30; aged 39-91 years; mild dementia, n = 26, chiefly AD, n = 36). RESULTS Good days/bad days were most often described as changes in the same core set of symptoms (e.g. less/more verbal repetition). In other cases, only good or only bad days were described (e.g., no bad days, better sense of humor on good days). Good days were typically associated with improved global cognition, function, interest, and initiation. Bad days were associated with frequent verbal repetition, poor memory, increased agitation and other disruptive behaviors. CONCLUSIONS Clinically important variability in symptoms appears common in AD and mixed dementia. Even so, what makes a day "good" is not simply more (or less) of what makes a day "bad". Further investigation of the factors that facilitate or encourage good days and mitigate bad days may help improve quality of life for patients and caregivers.
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Fallah N, Hsu CL, Bolandzadeh N, Davis J, Beattie BL, Graf P, Liu-Ambrose T. A multistate model of cognitive dynamics in relation to resistance training: the contribution of baseline function. Ann Epidemiol 2013; 23:463-8. [PMID: 23830936 DOI: 10.1016/j.annepidem.2013.05.008] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2013] [Revised: 05/08/2013] [Accepted: 05/19/2013] [Indexed: 10/26/2022]
Abstract
PURPOSE We investigated: (1) the effect of different targeted exercise training on an individual's overall probability for cognitive improvement, maintenance, or decline; and (2) the simultaneous effect of targeted exercise training and baseline function on the dynamics of executive functions when a multistate transition model is used. METHODS Analyses are based on a 12-month randomized clinical trial including 155 community-dwelling women 65-75 years of age who were randomly allocated to once-weekly resistance training (1x RT; n = 54), twice-weekly resistance training (2x RT; n = 52), or twice-weekly balance and tone training (BAT; n = 49). The primary outcome measure was performance on the Stroop test, an executive cognitive test of selective attention and conflict resolution. Secondary outcomes of executive functions were set shifting and working memory. RESULTS Individuals in the 1x RT or 2x RT group demonstrated a significantly greater probability for improved performance on the Stroop Test (0.49; 95% confidence interval, 0.41-0.57) compared with those in the BAT group (0.25; 95% confidence interval, 0.25-0.40). Resistance training had significant effects on transitions in selective attention and conflict resolution. CONCLUSIONS Resistance training is efficacious in improving a measure of selective attention and conflict resolution in older women, probably more so among those with greater baseline cognitive function.
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Affiliation(s)
- Nader Fallah
- Department of Physical Therapy, University of British Columbia, Vancouver, Canada
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Mitnitski A, Fallah N, Rockwood MRH, Rockwood K. Transitions in cognitive status in relation to frailty in older adults: a comparison of three frailty measures. J Nutr Health Aging 2011; 15:863-7. [PMID: 22159774 DOI: 10.1007/s12603-011-0066-9] [Citation(s) in RCA: 95] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Abstract
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.
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Affiliation(s)
- A Mitnitski
- Department of the Community Health and Epidemiology, Dalhousie University, Halifax, NS, Canada.
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Mitnitski AB, Fallah N, Dean CB, Rockwood K. A multi-state model for the analysis of changes in cognitive scores over a fixed time interval. Stat Methods Med Res 2011; 23:244-56. [PMID: 21937474 DOI: 10.1177/0962280211406470] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
In this article, we present the novel approach of using a multi-state model to describe longitudinal changes in cognitive test scores. Scores are modelled according to a truncated Poisson distribution, conditional on survival to a fixed endpoint, with the Poisson mean dependent upon the baseline score and covariates. The model provides a unified treatment of the distribution of cognitive scores, taking into account baseline scores and survival. It offers a simple framework for the simultaneous estimation of the effect of covariates modulating these distributions, over different baseline scores. A distinguishing feature is that this approach permits estimation of the probabilities of transitions in different directions: improvements, declines and death. The basic model is characterised by four parameters, two of which represent cognitive transitions in survivors, both for individuals with no cognitive errors at baseline and for those with non-zero errors, within the range of test scores. The two other parameters represent corresponding likelihoods of death. The model is applied to an analysis of data from the Canadian Study of Health and Aging (1991-2001) to identify the risk of death, and of changes in cognitive function as assessed by errors in the Modified Mini-Mental State Examination. The model performance is compared with more conventional approaches, such as multivariate linear and polytomous regressions. This model can also be readily applied to a wide variety of other cognitive test scores and phenomena which change with age.
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Affiliation(s)
- Arnold B Mitnitski
- Department of Medicine, Capital Health & Dalhousie University, Halifax, NS, Canada Department of Mathematics and Statistics, Dalhousie University, Halifax, NS, Canada
| | - Nader Fallah
- Geriatric Medicine Research Unit, Department of Medicine, Capital Health & Dalhousie University, Halifax, NS, Canada
| | - Charmaine B Dean
- Department of Statistics and Actuarial Science, Simon Fraser University, Vancouver, BC, Canada
| | - Kenneth Rockwood
- Geriatric Medicine Research Unit, Department of Medicine, Capital Health & Dalhousie University, Halifax, NS, Canada
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Mitnitski A, Fallah N, Rockwood K. A Multistate Model of Cognitive Dynamics in Relation to Frailty in Older Adults. Ann Epidemiol 2011; 21:507-16. [DOI: 10.1016/j.annepidem.2011.01.006] [Citation(s) in RCA: 30] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/24/2010] [Revised: 12/24/2010] [Accepted: 01/04/2011] [Indexed: 10/18/2022]
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Fallah N, Mitnitski A, Searle SD, Gahbauer EA, Gill TM, Rockwood K. Transitions in frailty status in older adults in relation to mobility: a multistate modeling approach employing a deficit count. J Am Geriatr Soc 2011; 59:524-9. [PMID: 21391943 PMCID: PMC3125634 DOI: 10.1111/j.1532-5415.2011.03300.x] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
OBJECTIVES To investigate how changes in frailty status and mortality risk relate to baseline frailty state, mobility performance, age, and sex. DESIGN Cohort study. SETTING The Yale Precipitating Events Project, New Haven, Connecticut. PARTICIPANTS Seven hundred fifty-four community-dwelling people aged 70 and older at baseline followed up at 18, 36, and 54 months. MEASUREMENTS Frailty status, assessed at 18-month intervals, was defined using a frailty index (FI) as the number of deficits in 36 health variables. Mobility was defined as time in seconds on the rapid gait test, in which participants walked back and forth over a 20-foot course as quickly as possible. Multistate transition probabilities were calculated with baseline frailty, mobility, age, and sex estimated using Poisson and logistic regressions in survivors and those who died, respectively. RESULTS In multivariable analyses, baseline frailty status and age were significantly associated with changes in frailty status and risk of death, whereas mobility was significantly associated with the frailty but not with mortality. At all values of the FI, participants with better mobility were more likely than those with poor mobility to remain stable or to improve. For example, at 54 months, 20.6% (95% confidence interval (CI)=16-25.2) of participants with poor mobility had the same or fewer deficits, compared with 32.4% (95% CI=27.9-36.9) of those with better mobility. CONCLUSION A multistate transition model effectively measured the probability of change in frailty status and risk of death. Mobility, age, and baseline frailty were significant factors in frailty state transitions.
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Affiliation(s)
- Nader Fallah
- Division of Geriatric Medicine, Dalhousie University, Halifax, NS Canada
| | - Arnold Mitnitski
- Division of Geriatric Medicine, Dalhousie University, Halifax, NS Canada
- Department of Mathematics and Statistics, Dalhousie University, Halifax, NS Canada
| | - Samuel D Searle
- Division of Geriatric Medicine, Dalhousie University, Halifax, NS Canada
| | - Evelyne A Gahbauer
- Yale University School of Medicine, Department of Internal Medicine, New Haven, CT USA
| | - Thomas M Gill
- Yale University School of Medicine, Department of Internal Medicine, New Haven, CT USA
| | - Kenneth Rockwood
- Division of Geriatric Medicine, Dalhousie University, Halifax, NS Canada
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