Cortisol secretion and functional disabilities in old age: importance of using adaptive control strategies

The Effect of Occupational Engagement on Lifestyle in Adults Living with Chronic Pain: A Systematic Review and Meta-analysis

Background. Healthy lifestyle is important to decrease health risks in individuals living with chronic pain. From an occupational therapy perspective, human health and lifestyle are linked to occupational engagement in meaningful everyday activities. This study is aimed at investigating the effect of including occupational engagement in chronic pain interventions on lifestyle. Methods. In this systematic review (PROSPERO reg. CRD42020159279), we included randomized controlled trials (RCTs) on interventions involving occupational engagement (i.e., occupational performance based on involvement, choice, positive meaning, and commitment) and assessing modifiable lifestyle factors: physical activity, body anthropometrics, alcohol consumption, smoking, stress, and sleep. We sought the databases Ovid MEDLINE, Embase, PsycINFO, CINAHL, Cochrane, Scopus, Web of Science, OTseeker, ClinicalTrials.gov, OpenGrey, and the web engine Google Scholar and citations and references of relevant publications. We evaluated methodological quality with the Cochrane risk-of-bias tool 2.0, determined the overall evidence certainty using the GRADE methodology, and performed meta-analysis when two or more trials reported on the outcomes. Results. Of the 9526 items identified, 286 were full text screened. We included twelve articles with eleven RCTs comprising 995 adults and assessing physical activity, sleep quality, stress, and Body Mass Index. Sufficient data for meta-analysis was only available for physical activity and sleep quality. The meta-analysis suggested a moderate increase in physical activity after behavioral interventions for fibromyalgia and musculoskeletal pain ( $\text{SMD}=0.69$ (0.29; 1.09)) and a small increase in sleep quality up to 6 months after multidisciplinary self-management of fibromyalgia ( $\text{SMD}=0.35$ (95% CI 0.08; 0.61)). The overall certainty of the evidence was deemed low. Conclusion. Including occupational engagement in chronic pain interventions may increase short-term physical activity and long-term sleep quality. Due to the few available RCTs including occupational engagement in chronic pain treatment for adults living with chronic pain, further high-quality RCTs are needed and will likely change the conclusion.

Functional Limitations, Volunteering, and Diurnal Cortisol Patterns in Older Adults

OBJECTIVES

Older adults often experience functional limitations that affect their everyday lives, but many of them continue to make positive contributions to society and benefit from these contributions themselves. We examine (a) whether older adults' functional limitations are associated with diurnal cortisol patterns and (b) whether these associations vary on volunteering days versus nonvolunteering days.

METHODS

Participants were adults aged older than 60 years (N = 435) from the National Study of Daily Experiences, part of the Midlife in the United States Study. They completed an initial interview on functional limitations and background characteristics, indicated volunteering activities in daily interviews, and also provided salivary samples across 4 days.

RESULTS

Multilevel models showed that older adults with greater functional limitations exhibited dysregulated cortisol awakening responses and diurnal cortisol slopes throughout the rest of the day, compared to older adults with lower limitations. Yet, we also observed a significant moderating effect of volunteering on these associations.

DISCUSSION

This study advances our understanding of functional limitations and cortisol stress responses, revealing the benefits of volunteering to older adults who experience these limitations. Rather than treating these older adults solely as care recipients, interventions should offer them opportunities to help others.

The Link between Activities of Daily Living and Cortisol in Late-Life Depression

OBJECTIVES

Dysregulated cortisol in older individuals is associated with neurodegeneration and executive dysfunction, among other negative health outcomes. Executive functioning deficits are believed to underlie declines in functioning among older adults. Despite these associations, there is limited research examining the relationship between cortisol and impaired functional status.

METHODS

The present study examined the relationship between cortisol and functional status in a community sample of 51 older adults with depression. Pearson correlations and ordinal regressions were used to determine whether greater cortisol dysregulation was associated with ADL and IADL impairment.

RESULTS

Results indicated that individuals who had higher levels of cortisol also tended to demonstrate greater functional deficits. These findings remained true when functional status was measured by either a clinician-rated tool or a self-report measure.

CONCLUSIONS

The results of this study provide preliminary support for the hypothesis that elevated cortisol, in the context of depression, is associated with functional status deficits in older adults.

CLINICAL IMPLICATIONS

Findings from this study begin to fill the gap in research examining the relationship between cortisol and functional impairment in older adults and suggest that unique information can be gathered with the use of different functional status measures.

Effect of music therapy on cortisol as a stress biomarker in children undergoing IV-line insertion

OBJECTIVE

An IV-line insertion can often provoke stress that can lead to an increase in cortisol levels. Complementary medication such as music therapy is needed to overcome the increase in cortisol levels. We conducted this study to determine the effect of music therapy on salivary cortisol levels in children with leukaemia undergoing IV-line insertion.

METHOD

This was a pre-experimental study with a pre- and post-test design. We analysed the salivary cortisol levels in 30 children with leukaemia undergoing IV-Line insertion from January until February 2018. Music was played using earphones after the completion of the IV-line insertion procedure. The salivary cortisol levels were analysed by an enzyme-linked immunosorbent assay (ELISA) test. Changes in cortisol levels were considered clinically significant if the differences were ≥0.05 ng/ml. The Wilcoxon test was used to test the effect of music therapy on cortisol levels and a p-value of <0.05 was considered statistically significant.

RESULT

Levels of cortisol before and after the music therapy had a median (min-max) of 4.14 (0.25-9.89) and 3.47 (0.16-15.31), respectively. The median difference of cortisol levels was 0.67 ng/ml. This change of ≥0.05 ng/ml indicates the clinical effect of music therapy on cortisol levels. Though the music therapy did not significantly affect salivary cortisol levels (p = 0.99), this study revealed the clinical effect of music therapy in reducing cortisol levels.

CONCLUSIONS

This study did not indicate a statistically significant effect of music therapy on cortisol levels of children with leukaemia during an IV-line insertion. However, the study findings reflect the clinical effect of music therapy in reducing cortisol levels.

Going the distance: The diurnal range of cortisol and its association with cognitive and physiological functioning

Cortisol features prominently in theories describing how chronic stress wears away at physical and cognitive health. The current study examines composite measures of physiological and cognitive functioning in relation to two aspects of daily cortisol: total daily output and change in levels throughout the day. Participants (N = 1001; aged 28-84 years-old) from the Midlife Development in the United States (MIDUS) study provided 4 daily saliva samples across four consecutive days and underwent a physical exam that provided information about six inter-related physiological systems that were combined into a measure of allostatic load. They also completed a phone-based battery of cognitive tasks, which provided a composite score combining memory, reasoning, and speed of processing performance. Total daily cortisol output was captured using area under the curve with respect to ground (AUCg). Change in cortisol levels was assessed using two methods: slope, calculated through piecewise spline models, and dynamic range, calculated by the difference between the day's highest and lowest log-cortisol levels. Findings indicate that, when examined together, overall cortisol output was not associated with either outcome, but a greater range in cortisol throughout the day was associated with both lower allostatic load and higher cognitive functioning. Results emphasize the importance of dynamic daily processes, assessed either using slopes or dynamic range, to both physiological and cognitive functioning.

A pilot study on salivary cortisol secretion and auditory P300 event-related potential in patients with physical disability-related stress

Objective: To evaluate the stress level and attention in workers with physical disabilities-related stress.Methods: Morning salivary cortisol was used as a stress marker while the event-related potential during the performance of the auditory oddball paradigm was conducted to investigate the attentive ability to sound stimuli. Eighteen injured workers (IP) and eighteen unaffected healthy adults (CP) were recruited for this study with half being men and the other half women (aged 21-55). Behavioral performance measures including reaction time (RT), accuracy rate, and commission error as well as the latency and amplitude of P300 wave over the central (Cz), centroparietal (CPz), and parietal (Pz) electroencephalogram electrode sites were used to compare the two groups.Results: This study demonstrated significantly higher salivary cortisol levels, longer RT, less accuracy to respond to the target during the auditory oddball paradigm in the IP group as compared to CP group. In addition, a significant prolongation of the peak latency of auditory P300 wave over CPz electrodes was also detected in IP group.Conclusion: The increased cortisol levels found in the IP group reflect the alteration of the basal hypothalamic-pituitary-adrenal axis as a result of the stresses of living with a physical disability. Delayed RT and the decreased in accuracy together with changing in peak latencies of auditory P300 wave indicate the impairment of attention networks in IP. Our study revealed that the patients with permanent physical disability.

Diurnal cortisol profiles, inflammation, and functional limitations in aging: Findings from the MIDUS study

OBJECTIVE

The current study examined the association between diurnal cortisol profiles, inflammation, and functional limitations, among adults ranging in age from 34-84 years.

METHOD

Participants (N = 799) completed Waves 2 (between 2004 and 2006) and 3 (between 2014 and 2016) of the Midlife Development in the United States Survey. At Wave 2, participants provided saliva samples across 4 consecutive days, from which cortisol was assayed. Previously validated diurnal cortisol profiles (i.e., normative, flattened, or elevated) were examined in relation to concurrent inflammation risk burden and to predict long-term changes in functional limitations.

RESULTS

Compared with participants with normative profiles across all interview days, participants with dysregulated profiles across all interview days (i.e., all days elevated, flattened, or a combination of elevated and flattened) showed greater concurrent inflammation risk burden and more functional limitations at follow-up. Regions of significance testing indicated that the association was significant beginning at age 60 for inflammation risk burden and beginning at age 66 for functional limitations. Variable profiles (i.e., a mix of normative and flattened and/or elevated across the four days of assessment) were not significantly associated with these health indices.

CONCLUSIONS

Findings, consistent with the theoretical model of Strength and Vulnerability Integration, illustrate the importance of considering age when examining cortisol and its association with other health indices. (PsycINFO Database Record

Promoting physical activity in people with intellectual and multiple disabilities through a basic technology-aided program

This study assessed a technology-aided program (monitoring responding, and ensuring preferred stimulation and encouragements) for promoting physical activity with 11 participants with severe/profound intellectual and multiple disabilities. Each participant was provided with an exercise device (e.g. a static bicycle and a stepper) and exposed to the program according to an ABAB design, in which A and B represented baseline and intervention phases, respectively. Data recording concerned (a) the participants' responses with the exercise device (e.g. pedaling) during baseline and intervention phases and (b) their heart rates during the last intervention phase. The results showed that all participants had significant increases in responding with the exercise devices during the intervention phases. Heart-rate values during the intervention sessions indicated that the participants' responding during those sessions mostly amounted to moderate-intensity physical activity, with potential benefits for their overall physical condition. Implications of the findings and questions for future research in the area were discussed.

The interplay of subjective social status and essentialist beliefs about cognitive aging on cortisol reactivity to challenge in older adults

Older adults are more likely than younger adults to experience stress when confronted with cognitive challenges. However, little is known about individual differences that might explain why some older adults exhibit stronger stress responses than others. We examined the interplay of two social-cognitive factors to explain older adults' cortisol reactivity: (1) subjective social status, and (2) essentialist beliefs about cognitive aging. We hypothesized that, depending on whether older adults believe that aging-related cognitive decline is inevitable versus modifiable, low subjective social status should lead to stronger or weaker cortisol reactivity. Using longitudinal data, we assessed the impact of cognitive challenges on stress reactivity in a sample of older adults (N = 389; 61-86 years). As predicted, regression analyses confirmed that 44 min after cognitively challenging tasks, older adults exhibited a significantly different cortisol reactivity depending on their subjective social status and their essentialist beliefs about cognitive aging. Specifically, older adults with low subjective social status and high essentialist beliefs showed a significantly elevated cortisol reactivity. We discuss the role of essentialist beliefs about cognitive aging to predict when and why high versus low subjective social status leads to stress responses in older adults.

Resting steroid hormone concentrations in lifetime exercisers and lifetime sedentary males

INTRODUCTION

Advancing age in men is associated with a progressive decline in serum testosterone (T) and interactions between exercise, aging and androgen status are poorly understood. The primary aim of this study was to establish the influence of lifelong training history on serum T, cortisol (C) and sex hormone binding globulin (SHBG) in aging men. A secondary aim was to determine the agreement between serum and salivary measurement of steroid hormones in ageing men.

METHODS

Serum and salivary steroid hormones (serum C, T and SHBG, and salivary measures of C and T) were determined and compared between two distinct groups; lifelong exercising males (LE [n = 20], 60.4 ± 4.7 year) and age matched lifelong sedentary individuals (SED [n = 28], 62.5 ± 5.3 years).

RESULTS

T-test revealed a lack of significant differences for serum C or SHBG between LE and SED, while Mann-Whitney U revealed a lack of differences in total T (TT), bioavailable T (bio-T) or free testosterone (free-T). Further, salivary T (sal-T) did not correlate with serum markers of T in LE, SED, or when pooled (r = 0.040; p > 0.05).

CONCLUSIONS

Findings from this investigation suggested that resting levels of serum T and calculated free-T was unable to distinguish between diverse lifelong training histories in aging men. Further, sal-T was not an appropriate indicator of serum T and calculated free-T values in older males and considerable caution should be exercised when interpreting sal-T measurements in aging males.

Self-esteem change and diurnal cortisol secretion in older adulthood

OBJECTIVE

Research suggests that self-esteem can decline in older adulthood. This process could remove a buffer that normally protects individuals against distress-related changes in cortisol secretion. We examined this possibility by testing whether change in self-esteem would predict alterations in cortisol secretion, particularly among older adults who reported high levels of depressive symptoms or perceived stress.

METHODS

147 older adults (aged 60+) completed three days of diurnal cortisol measurements at three different time points, namely every two years over a total period of four years. Measures of self-esteem, depressive symptoms, and perceived stress were assessed at T1 and T2. Potential demographic and health-related confounds were measured at baseline (partnership status, SES, mortality risk index, and medication).

RESULTS

Linear regression models indicated that a decline in self-esteem from T1 to T2 predicted elevated cortisol output (AUCG) from T2 to T3, F (1, 137)=8.09, β=-.25, R(2)=.05, p=.005. Interaction analyses revealed that this association was particularly strong among participants who experienced higher T1 or T2 levels of depressive symptoms or perceived stress, +1SD: βs=-.34 to -.51, ps<.001, but not significant among their counterparts who reported relatively lower levels of depressive symptoms or perceived stress, -1SD: βs=.03 to 11, ps>.43.

CONCLUSIONS

Declines in self-esteem represent a mechanism that contributes to higher levels of diurnal cortisol secretion if older adults experience psychological distress. Increases in self-esteem, by contrast, can ameliorate older adults' cortisol regulation in stressful circumstances.

Cortisol profile and depressive symptoms in older adults residing in Brazil and in Canada

BACKGROUND AND AIM

How cortisol, a stress biological marker, differs according to depressive symptoms has mostly been examined in high-income countries. Including low- and middle-income countries in research on this matter would allow examining a wider range of exposure to adversity and improving the estimates of the associations between diurnal cortisol and depression. The aim of this study is to compare the profile of diurnal cortisol and depressive symptoms in 65- to 74-year-old residents of Santa Cruz (in an underdeveloped region, northeast Brazil, n = 64) and Saint-Bruno (a suburban area, QC, Canada, n = 60).

METHODS

Home interviews included assessments of socioeconomic variables, health behaviors, depressive symptoms (Center for Epidemiologic Studies Depression Scale, CES-D) and Cortisol Awakening Response (CAR: awakening, 30, 60 min afterward), and at 1500 hours and bedtime from saliva collected over 2 days. Mixed linear models were used to estimate the associations between diurnal cortisol and depressive symptoms.

RESULTS

Santa Cruz residents had lower cortisol levels upon awakening (β = -1.24, p = 0.04) and elevated bedtime levels (β = 20.29, p < 0.001) indicating chronic stress compared to Saint-Bruno residents. Elevated depressive symptoms were associated with a blunted CAR (flatter slope, indicative of chronic stress) in Santa Cruz residents (β = -0.19, p = 0.04), while greater diurnal cortisol levels (larger area under the curve), indicative of moderate stress, were observed in Saint-Bruno residents (β = 1.96, p = 0.047).

CONCLUSION

Adverse living conditions in this remote area of Brazil may lead to a state of chronic stress and a different relationship with elevated depressive symptoms from persons aging in a Canadian suburban area.

Age-dependent and gender-dependent regulation of hypothalamic-adrenocorticotropic-adrenal axis

Tightly regulated output of glucocorticoids is critical to maintaining immune competence, the structure of neurons, muscle, and bone, blood pressure, glucose homeostasis, work capacity, and vitality in the human and experimental animal. Age, sex steroids, gender, stress, body composition, and disease govern glucocorticoid availability through incompletely understood mechanisms. According to an ensemble concept of neuroendocrine regulation, successful stress adaptations require repeated incremental signaling adjustments among hypothalamic corticotropin-releasing hormone and arginine vasopressin, pituitary adrenocorticotropic hormone, and adrenal corticosteroids. Signals are transduced via (positive) feedforward and (negative) feedback effects. Age and gonadal steroids strongly modulate stress-adaptive glucocorticoid secretion by such interlinked pathways.

Associations between dispositional optimism and diurnal cortisol in a community sample: when stress is perceived as higher than normal

OBJECTIVES

This study examined whether dispositional optimism would be associated with reduced levels of cortisol secretion among individuals who perceive stress levels that are either higher than their normal average (i.e., within-person associations) or higher than the stress levels of other individuals (i.e., between-person associations).

METHODS

Stress perceptions and four indicators of diurnal cortisol (area-under-the-curve, awakening, afternoon/evening, and cortisol awakening response [CAR] levels) were assessed on 12 different days over 6 years in a sample of 135 community-dwelling older adults.

RESULTS

Hierarchical linear models showed that although pessimists secreted relatively elevated area-under-the-curve, awakening, and afternoon/evening levels of cortisol (but not CAR) on days they perceived stress levels that were higher than their normal average, optimists were protected from these stress-related elevations in cortisol. However, when absolute stress levels were compared across participants, there was only a significant effect for predicting CAR (but not the other cortisol measures), indicating that optimism was associated particularly strongly with a reduced CAR among participants who experienced high levels of stress.

CONCLUSIONS

Dispositional optimism can buffer the association between stress perceptions and elevated levels of diurnal cortisol when individuals perceive higher-than-normal levels of stress, and it may predict a reduced CAR among individuals who generally perceive high stress levels. Research should examine relative, in addition to absolute, levels of stress to identify the personality factors that help individuals adjust to psychological perceptions of stress.

Self-regulation of unattainable goals in suicide attempters: a two year prospective study

BACKGROUND

Although suicide is a global public health concern with approximately one million people dying by suicide annually, our knowledge of the proximal risk mechanisms is limited. In the present study, we investigated the utility of two proximal mechanisms (goal disengagement and goal reengagement) in the prediction of hospital-treated self-harm repetition in a sample of suicide attempters.

METHODS

Two hundred and thirty-seven patients hospitalised following a suicide attempt completed a range of clinical (depression, anxiety, hopelessness, suicidal ideation) and goal regulation measures (goal reengagement and disengagement) while in hospital. They were followed up two years later to determine whether they had been re-hospitalised with self-harm between baseline and the follow-up.

RESULTS

Self-harm hospitalisation in the past 10 years, suicidal ideation and difficulty reengaging in new goals independently predicted self-harm two years later. In addition, among younger people, having difficulty re-engaging in new goals further predicted self-harm re-hospitalisation when disengagement from existing unattainable goals was also low. Conversely, the deleterious impact of low reengagement in older people was elevated when goal disengagement was also high.

LIMITATIONS

Only hospital-treated self-harm and suicide were recorded at follow-up, episodes of less medically serious self-harm were not recorded.

CONCLUSIONS

Suicidal behaviour is usefully conceptualised in terms of goal self-regulation following the experience of unattainable goals. Treatment interventions should target the self-regulation of goals among suicide attempters and clinicians should recognise that different regulation processes need to be addressed at different points across the lifespan.

Associations between health-related self-protection, diurnal cortisol, and C-reactive protein in lonely older adults

OBJECTIVES

The aim of this study was to examine whether health-related self-protection (e.g., using positive reappraisals or avoiding self-blame) prevents lonely older adults from exhibiting increases in diurnal cortisol secretion and higher levels of C-reactive protein (CRP).

METHODS

This longitudinal study (n = 122) examined diurnal cortisol levels (area under the curve) at baseline and 2-year follow-up. Levels of CRP were measured at 6-year follow-up. The main predictors included baseline levels of loneliness and health-related self-protection.

RESULTS

Among lonely participants, baseline self-protection predicted an amelioration of 2-year increases in diurnal cortisol volume (β = -.34, p = .03) and lower levels of CRP at 6-year follow-up (β = -.42, p = .006). These significant associations were not found among nonlonely participants (β < .14, p = .33). In addition, mediation analyses demonstrated that the buffering effect of self-protection on lonely older adults' levels of CRP at 6-year follow-up was statistically mediated by 2-year changes in cortisol volume (β = -.16, p = .06).

CONCLUSIONS

These findings suggest that lonely older adults may ameliorate biologic disturbances if they engage in self-protection to cope with their health threats.

Sleep duration buffers diurnal cortisol increases in older adulthood

This study examined the long-term associations between reports of sleep duration and diurnal cortisol secretion in older adulthood. It was hypothesized that longer sleep would protect older adults against increases in diurnal cortisol secretion over time. We tested this hypothesis using three waves of data from a 4-year longitudinal study involving 157 older adults. Results from growth curve and cross-lagged panel analyses demonstrated that levels and increases in sleep duration buffered long-term elevations of diurnal cortisol secretion. Reversed analyses indicated that diurnal cortisol secretion did not predict changes in sleep duration over time. These results were independent from sociodemographic characteristics (i.e., age, sex, partnership status, and education) and health-related variables (i.e., chronic illness, medication usage, body mass index, and smoking). They suggest that long sleep exerts restorative functions and protects older adults from exhibiting increases in diurnal cortisol secretion over time.

The healing power of well-being

Neuroendocrine system plays an important role in modulating our body functions and emotions. At the same time, emotions implicate a pivotal role in the regulation of brain function and neuroendocrine system. Negative affective states such as depression and stress are associated with premature mortality and increase the risk of various fatal diseases. It has been suggested that positive affective states are protective and improve our health and productiveness. Several potential mechanisms have been posited to account for these associations including improved health behaviour, direct physiological benefits, enhanced resistance and recovery from stress among individuals with high versus low positive emotional resources. This review summarises information concerning the neuronal and hormonal systems in mood, impact of negative and positive affective states on the level of cortisol, epinephrine, serotonin, dopamine and endorphins. The functional correlation of neuronal and hormonal systems in the development of diseases and their ability to enhance health-relevant biological processes are also evaluated.

Making up for lost opportunities: the protective role of downward social comparisons for coping with regrets across adulthood

Two longitudinal studies showed that if adults confront low opportunities to overcome regrets, downward social comparisons can exert self-protective functions across the adult life span, irrespective of age (Study 1 N = 104 young and older adults, Study 2 N = 51 older adults). Both studies found that downward relative to upward social comparisons were associated with improvements in participants' positive (but not negative) affect, if they perceived low as opposed to high opportunities to overcome regrets. Moreover, Study 2 showed that this beneficial effect on change in positive affect mediated the experience of fewer cold symptoms over time. Supplemental analyses further indicated that the mechanism linking social comparison processes and opportunities with positive (but not negative) affect was associated with the capacity for goal reengagement. In addition, these analyses showed that the obtained effects were largely unrelated to the severity of regret-related consequences and thus ruled out an alternative explanation of the findings.

Promoting functional health in midlife and old age: long-term protective effects of control beliefs, social support, and physical exercise

Background

Previous studies have examined physical risk factors in relation to functional health, but less work has focused on the protective role of psychological and social factors. We examined the individual and joint protective contribution of control beliefs, social support and physical exercise to changes in functional health, beyond the influence of health status and physical risk factors in middle-aged and older adults. Given that functional health typically declines throughout adulthood, it is important to identify modifiable factors that can be implemented to maintain functioning, improve quality of life, and reduce disability.

Methodology/Principal Findings

We conducted a national longitudinal study, Midlife in the United States (MIDUS), with assessments in 1995–1996 and 2004–2006, and 3,626 community-residing adults, aged 32 to 84, were included in the analyses. Functional health (Physical Functioning subscale of the SF-36) and protective factors were measured at both occasions. While controlling for socio-demographic, health status, and physical risk factors (large waist circumference, smoking, and alcohol or drug problems), a composite of the three protective variables (control beliefs, social support, and physical exercise) at Time 1 was significantly related to functional health change. The more of these factors at Time 1, the better the health maintenance over 10 years. Among middle-aged and older adults, declines in health were significantly reduced with an increased number of protective factors.

Conclusion/Significance

Age-related declines in health were reduced among those with more protective factors up to a decade earlier in life. Modifiable psychological, social, and physical protective factors, individually and in the aggregate, are associated with maintenance of functional health, beyond the damaging effects of physical risk factors. The results are encouraging for the prospect of developing interventions to promote functional health and for reducing public health expenditures for physical disability in later life.