A template for physical resilience research in older adults: Methods of the PRIME-KNEE study

Trajectories of Physical Resilience Among Older Veterans With Stage 4 CKD

RATIONALE & OBJECTIVE

Although functional impairment is common among older adults with chronic kidney disease (CKD), functional reserve before an acute health event and physical resilience after the event have not been characterized in this population. The purpose of this study was to identify distinct patterns of physical function before and after an acute health event among older veterans with stage 4 CKD.

STUDY DESIGN

Prospective cohort study.

SETTING & PARTICIPANTS

National sample of veterans≥70 years of age with an estimated glomerular filtration rate (eGFR) of<30mL/min/1.73m2 who had an acute care encounter (emergency department visit or hospitalization) during the follow-up period (n = 272).

PREDICTORS

Demographic characteristics, eGFR, basic and instrumental activities of daily living (ADL/IADL) difficulty, symptom burden, cognition, depressive symptoms, social support.

OUTCOME

Function measured using the life-space mobility assessment obtained by telephone survey before and after an acute care encounter.

ANALYTICAL APPROACH

General growth mixture models to identify classes of functional trajectories. Calculation of percentages for demographic characteristics and means for eGFR, ADL/IADL difficulty, symptom burden, cognition, depressive symptoms, and social support by trajectory class.

RESULTS

Four trajectory classes were identified and characterized by different levels of life-space mobility before (reserve) and change in life-space mobility after (resilience) an acute care encounter: (1) low reserve, low resilience (n=91), (2) high reserve, high resilience (n=23), (3) moderate reserve, moderate resilience (n=89), and (4) high reserve, low resilience (n=69). Mean levels of ADL/IADL difficulty, symptom burden, cognition, and depressive symptoms, but not demographic characteristics, eGFR, or social support, differed by trajectory class.

LIMITATIONS

Veteran cohort was primarily male.

CONCLUSIONS

Among older adults with stage 4 CKD, physical function trajectories before and after an acute health event vary. Integrating reserve and resilience into care for this population may be useful for anticipating changes in function and developing tailored treatment plans.

Preoperative electroencephalographic alpha-power changes with eyes opening are associated with postoperative attention impairment and inattention-related delirium severity

BACKGROUND

In the eyes-closed, awake condition, EEG oscillatory power in the alpha band (7-13 Hz) dominates human spectral activity. With eyes open, however, EEG alpha power substantially decreases. Less alpha attenuation with eyes opening has been associated with inattention; thus, we analysed whether reduced preoperative alpha attenuation with eyes opening is associated with postoperative inattention, a delirium-defining feature.

METHODS

Preoperative awake 32-channel EEG was recorded with eyes open and eyes closed in 71 non-neurological, noncardiac surgery patients aged ≥ 60 years. Inattention and other delirium features were assessed before surgery and twice daily after surgery until discharge. Eyes-opening EEG alpha-attenuation magnitude was analysed for associations with postoperative inattention, primarily, and with delirium severity, secondarily, using multivariate age- and Mini-Mental Status Examination (MMSE)-adjusted logistic and proportional-odds regression analyses.

RESULTS

Preoperative alpha attenuation with eyes opening was inversely associated with postoperative inattention (odds ratio [OR] 0.73, 95% confidence interval [CI]: 0.57, 0.94; P=0.038). Sensitivity analyses showed an inverse relationship between alpha-attenuation magnitude and inattention chronicity, defined as 'never', 'newly', or 'chronically' inattentive (OR 0.76, 95% CI: 0.62, 0.93; P=0.019). In addition, preoperative alpha-attenuation magnitude was inversely associated with postoperative delirium severity (OR 0.79, 95% CI: 0.65, 0.95; P=0.040), predominantly as a result of the inattention feature.

CONCLUSIONS

Preoperative awake, resting, EEG alpha attenuation with eyes opening might represent a neural biomarker for risk of postoperative attentional impairment. Further, eyes-opening alpha attenuation could provide insight into the neural mechanisms underlying postoperative inattention risk.

Psychological Correlates of Self-Rated Resilience in the Context of Subjective Cognitive Concerns in Older Adults

OBJECTIVE

The purpose of this study was to evaluate psychological correlates of self-rated resilience, as assessed with the 10-item version of the Connor-Davidson Resilience Scale (CD-RISC-10), in older adults. In particular, we were interested in the degree to which self-rated resilience might be a protective factor against cognitive decline.

METHOD

In total, 100 adults aged 60-90 years who had been referred because of subjective cognitive concerns completed self-report measures of resilience, symptoms of anxiety and depression, and satisfaction with life. They also completed a test of learning and memory. Ratings about daily functioning at home and in the community were obtained from both participants and proxy informants.

RESULTS

Resilience ratings correlated strongly negatively with concurrent self-rated symptoms of anxiety and depression, and strongly positively with self-rated life satisfaction. However, only informant ratings of daily functioning correlated with actual participant performance on a test of learning and memory, with lower ratings being associated with worse test performance.

CONCLUSIONS

Self-rated resilience, as measured by the CD-RISC-10, is primarily related to subjective well-being and does not inform sufficiently about relative risk for cognitive dysfunction in older adults.

Engineering Virtuous health habits using Emotion and Neurocognition: Flexibility for Lifestyle Optimization and Weight management (EVEN FLOW)

Interventions to preserve functional independence in older adults are critically needed to optimize 'successful aging' among the large and increasing population of older adults in the United States. For most aging adults, the management of chronic diseases is the most common and impactful risk factor for loss of functional independence. Chronic disease management inherently involves the learning and adaptation of new behaviors, such as adopting or modifying physical activity habits and managing weight. Despite the importance of chronic disease management in older adults, vanishingly few individuals optimally manage their health behavior in the service of chronic disease stabilization to preserve functional independence. Contemporary conceptual models of chronic disease management and health habit theory suggest that this lack of optimal management may result from an underappreciated distinction within the health behavior literature: the behavioral domains critical for initiation of new behaviors (Initiation Phase) are largely distinct from those that facilitate their maintenance (Maintenance Phase). Psychological factors, particularly experiential acceptance and trait levels of openness are critical to engagement with new health behaviors, willingness to make difficult lifestyle changes, and the ability to tolerate aversive affective responses in the process. Cognitive factors, particularly executive function, are critical to learning new skills, using them effectively across different areas of life and contextual demands, and updating of skills to facilitate behavioral maintenance. Emerging data therefore suggests that individuals with greater executive function are better able to sustain behavior changes, which in turn protects against cognitive decline. In addition, social and structural supports of behavior change serve a critical buffering role across phases of behavior change. The present review attempts to address these gaps by proposing a novel biobehavioral intervention framework that incorporates both individual-level and social support system-level variables for the purpose of treatment tailoring. Our intervention framework triangulates on the central importance of self-regulatory functioning, proposing that both cognitive and psychological mechanisms ultimately influence an individuals' ability to engage in different aspects of self-management (individual level) in the service of maintaining independence. Importantly, the proposed linkages of cognitive and affective functioning align with emerging individual difference frameworks, suggesting that lower levels of cognitive and/or psychological flexibility represent an intermediate phenotype of risk. Individuals exhibiting self-regulatory lapses either due to the inability to regulate their emotional responses or due to the presence of executive functioning impairments are therefore the most likely to require assistance to preserve functional independence. In addition, these vulnerabilities will be more easily observable for individuals requiring greater complexity of self-management behavioral demands (e.g. complexity of medication regimen) and/or with lesser social support. Our proposed framework also intuits several distinct intervention pathways based on the profile of self-regulatory behaviors: we propose that individuals with intact affect regulation and impaired executive function will preferentially respond to 'top-down' training approaches (e.g., strategy and process work). Individuals with intact executive function and impaired affect regulation will respond to 'bottom-up' approaches (e.g., graded exposure). And individuals with impairments in both may require treatments targeting caregiving or structural supports, particularly in the context of elevated behavioral demands.

Assessment of Physical Resilience Using Residual Methods and Its Association With Adverse Outcomes in Older Adults

Background and Objectives

Physical resilience (PR) is recognized as the ability to recover from the adverse effects of a stressor. However, there is a lack of consensus on how to optimally measure PR in older adults in general. We aimed to measure PR using residuals from regression analyses and investigated its association with adverse outcomes in older adults.

Research Design and Methods

A total of 6 508 older adults were included from the National Health and Aging Trends Study, which was a population-based prospective cohort study. PR was assessed using residual methods from a linear model regressing the short physical performance battery on clinical diseases, age, sex, race/ethnicity, and health condition. Adverse outcomes included all-cause mortality, falls, and overnight hospitalization.

Results

The mean age was 77.48 (7.84) years. Increased PR was associated with a lower risk of all-cause mortality (hazard ratio [HR] = 0.85, 95% confidence interval [CI]: 0.83-0.87). Compared to participants with reduced PR, those with normal PR had a lower risk for mortality (HR = 0.51, 95% CI: 0.46-0.56). Specifically, restricted cubic spline regression revealed a dose-response relationship between PR and all-cause mortality (p-overall < .0001, p-nonlinear = .011). Additionally, we also found significant associations of increased PR with lower risks of falls (HR = 0.98, 95% CI: 0.96-0.99) and overnight hospitalization (HR = 0.98, 95% CI: 0.97-1.00).

Discussion and Implications

PR, measured by residual methods, was robustly and independently associated with all-cause mortality, falls, and overnight hospitalization. Our findings provide evidence that this approach may be a simple and feasible strategy to assess PR.

Ageing and physical resilience after health stressors

The objectives of this article are to introduce a conceptual framework for physical resilience in the context of ageing and to discuss key elements and challenges in the design of studies of physical resilience after health stressors. Advancing age is associated with increasing exposure to multiple stressors and declining capacity to respond to health stressors. Resilience is defined broadly as the ability to resist or recover well from the adverse effects of a health stressor. In ageing-related study designs of physical resilience after a health stressor, this dynamic resilience response can be observed as changes in repeated measures of function or health status in various domains important to older adults. Methodologic issues in selecting the study population, defining the stressor, covariates, outcomes, and analytic strategies are highlighted in the context of an ongoing prospective cohort study of physical resilience after total knee replacement surgery. The article concludes with approaches to intervention development to optimize resilience.

An overview of the resilience world: Proceedings of the American Geriatrics Society and National Institute on Aging State of Resilience Science Conference

Resilience, which relates to one's ability to respond to stressors, typically declines with age and the development of comorbid conditions in older organisms. Although progress has been made to improve our understanding of resilience in older adults, disciplines have employed different frameworks and definitions to study various aspects of older adults' response to acute or chronic stressors. "Overview of the Resilience World: State of the Science," a bench-to-bedside conference on October 12-13, 2022, was sponsored by the American Geriatrics Society and National Institute on Aging. This conference, summarized in this report, explored commonalities and differences among the frameworks of resilience most commonly used in aging research in the three domains of resilience: physical, cognitive, and psychosocial. These three main domains are intertwined, and stressors in one domain can lead to effects in other domains. The themes of the conference sessions included underlying contributors to resilience, the dynamic nature of resilience throughout the life span, and the role of resilience in health equity. Although participants did not agree on a single definition of "resilience(s)," they identified common core elements of a definition that can be applied to all domains and noted unique features that are domain specific. The presentations and discussions led to recommendations for new longitudinal studies of the impact of exposures to stressors on resilience in older adults, the use of new and existing cohort study data, natural experiments (including the COVID-19 pandemic), and preclinical models for resilience research, as well as translational research to bring findings on resilience to patient care.

A Real-Time Neurophysiologic Stress Test for the Aging Brain: Novel Perioperative and ICU Applications of EEG in Older Surgical Patients

As of 2022, individuals age 65 and older represent approximately 10% of the global population [1], and older adults make up more than one third of anesthesia and surgical cases in developed countries [2, 3]. With approximately > 234 million major surgical procedures performed annually worldwide [4], this suggests that > 70 million surgeries are performed on older adults across the globe each year. The most common postoperative complications seen in these older surgical patients are perioperative neurocognitive disorders including postoperative delirium, which are associated with an increased risk for mortality [5], greater economic burden [6, 7], and greater risk for developing long-term cognitive decline [8] such as Alzheimer's disease and/or related dementias (ADRD). Thus, anesthesia, surgery, and postoperative hospitalization have been viewed as a biological "stress test" for the aging brain, in which postoperative delirium indicates a failed stress test and consequent risk for later cognitive decline (see Fig. 3). Further, it has been hypothesized that interventions that prevent postoperative delirium might reduce the risk of long-term cognitive decline. Recent advances suggest that rather than waiting for the development of postoperative delirium to indicate whether a patient "passed" or "failed" this stress test, the status of the brain can be monitored in real-time via electroencephalography (EEG) in the perioperative period. Beyond the traditional intraoperative use of EEG monitoring for anesthetic titration, perioperative EEG may be a viable tool for identifying waveforms indicative of reduced brain integrity and potential risk for postoperative delirium and long-term cognitive decline. In principle, research incorporating routine perioperative EEG monitoring may provide insight into neuronal patterns of dysfunction associated with risk of postoperative delirium, long-term cognitive decline, or even specific types of aging-related neurodegenerative disease pathology. This research would accelerate our understanding of which waveforms or neuronal patterns necessitate diagnostic workup and intervention in the perioperative period, which could potentially reduce postoperative delirium and/or dementia risk. Thus, here we present recommendations for the use of perioperative EEG as a "predictor" of delirium and perioperative cognitive decline in older surgical patients.

Physical activity is a potential measure of physical resilience in older adults receiving hemodialysis

Background

Physical resilience, or the ability to recover after a physical stressor, declines with aging. Efforts to preserve physical resilience in the older dialysis population are critically needed; however, validated, patient-centered measures that are sensitive to change are also needed. Our objective was to assess accelerometer-derived step count variability, or a measure of intra-individual variation in physical activity, as a potential measure of physical resilience among older adults receiving hemodialysis.

Methods

Community-dwelling ambulatory older adults receiving in-center hemodialysis were prospectively enrolled. Participants wore wrist accelerometers during daytime hours on both dialysis and non-dialysis days up to 14 days, and the feasibility of accelerometer use was assessed from wear time. We used accelerometer data to compute step counts in 4-hour blocks and step count variability. Physical function was assessed with the Short Physical Performance Battery (SPPB which includes gait speed test), grip strength, activities of daily living (ADLs) instruments, and life space mobility. We assessed interval fatigue (subjective rating from 0 to 10) on dialysis and non-dialysis days and self-reported recovery time. We assessed the correlations of step count variability with measures of physical function and step count and interval fatigue.

Results

Of 37 enrolled participants, 29 had sufficient accelerometer data for analyses. Among the 29 participants, mean (SD) age was 70.6(4.8) years, and 55% (n=16) were male and 72% (n=21) were Black race. Participants were largely sedentary with median (Q1-Q3) self-reported total kilocalories per week of 200 (36-552). Step count variability was positively correlated with measures of physical function: SPPB (r=0.50, p<0.05), gait speed (r=0.59, p<0.05), handgrip strength (r=0.71, p<0.05), Instrumental ADLs (r=0.44, p<0.05) and life space mobility (r=0.54, p<0.05).There was a weak inverse correlation between post-dialysis step counts (4-hour blocks after a dialysis session) and post-dialysis interval fatigue [r=-0.19 (n=102, p=0.06).

Conclusions

Physical activity assessment via accelerometer is feasible for older adults receiving hemodialysis. Step count variability correlated with physical function, so it may be a novel measure of physical resilience. Further studies are needed to validate this measure.

Reserve and resilience in CKD: concept introduction and baseline results from the Physical REsilience Prediction in Advanced REnal Disease (PREPARED) study

BACKGROUND

The purpose of this manuscript is to introduce reserve and resilience as novel concepts in chronic kidney disease (CKD) research and present baseline data from a unique prospective cohort study designed to characterize recovery from functional decline after a health event.

METHODS

The Physical REsilience Prediction in Advanced REnal Disease (PREPARED) study recruited a national, prospective cohort of Veterans ≥70 years old with an estimated glomerular filtration rate (eGFR) < 30 ml/min/1.73 m², prior nephrology care, and at high risk for hospitalization. Electronic health record data were paired with telephone surveys. Self-reported measures of reserve included physical, psychological, and cognitive capacity and environmental resources. We calculated counts (frequencies) and medians (25th, 75th percentiles) for baseline measures of reserve. The study's longitudinal follow-up of physical function every 8 weeks or following an acute care encounter, which will be used to define resilience, is ongoing.

RESULTS

Participants had a median (25th, 75th percentile) age of 76.3 (72.8, 81.4) years and eGFR of 23.4 (18.2, 28.8) ml/min/1.73 m²; 23.3% were Black, and 97.4% were male, 91.6% had hypertension, 67.4% had diabetes mellitus, 46.0% had coronary heart disease, and 39.8% had heart failure. Baseline measures of physical, psychological, and cognitive domains showed low reserve on average, but with wide ranges.

CONCLUSIONS

Despite similar levels of kidney function, older adults participating in PREPARED had a wide range of measures of reserve in other health domains. Non-renal measures of reserve may be important indicators of capacity of CKD patients to recover after acute care encounters.

Resilience: Biological Basis and Clinical Significance - A Perspective Report from the International Conference on Frailty and Sarcopenia Research (ICFSR) Task Force

The Resilience is a construct receiving growing attention from the scientific community in geriatrics and gerontology. Older adults show extremely heterogeneous (and often unpredictable) responses to stressors. Such heterogeneity can (at least partly) be explained by differences in resilience (i.e., the capacity of the organism to cope with stressors). The International Conference on Frailty and Sarcopenia Research (ICFSR) Task Force met in Boston (MA,USA) on April 20, 2022 to discuss the biological and clinical significance of resilience in older adults. The identification of persons with low resilience and the prompt intervention in this at-risk population may be critical to develop and implement preventive strategies against adverse events. Unfortunately, to date, it is still challenging to capture resilience, especially due to its dynamic nature encompassing biological, clinical, subjective, and socioeconomic factors. Opportunities to dynamically measure resilience were discussed during the ICFSR Task Force meeting, emphasizing potential biomarkers and areas of intervention. This article reports the results of the meeting and may serve to support future actions in the field.