Data-driven MRI analysis reveals fitness-related functional change in default mode network and cognition following an exercise intervention

Previous research has indicated that cardiorespiratory fitness (CRF) is structurally and functionally neuroprotective in older adults. However, questions remain regarding the mechanistic role of CRF on cognitive and brain health. The purposes of this study were to investigate if higher pre-intervention CRF was associated with greater change in functional brain connectivity during an exercise intervention and to determine if the magnitude of change in connectivity was related to better post-intervention cognitive performance. The sample included low-active older adults (n = 139) who completed a 6-month exercise intervention and underwent neuropsychological testing, functional neuroimaging, and CRF testing before and after the intervention. A data-driven multi-voxel pattern analysis was performed on resting-state MRI scans to determine changes in whole-brain patterns of connectivity from pre- to post-intervention as a function of pre-intervention CRF. Results revealed a positive correlation between pre-intervention CRF and changes in functional connectivity in the precentral gyrus. Using the precentral gyrus as a seed, analyses indicated that CRF-related connectivity changes within the precentral gyrus were derived from increased correlation strength within clusters located in the Dorsal Attention Network (DAN) and increased anti-correlation strength within clusters located in the Default Mode Network (DMN). Exploratory analysis demonstrated that connectivity change between the precentral gyrus seed and DMN clusters were associated with improved post-intervention performance on perceptual speed tasks. These findings suggest that in a sample of low-active and mostly lower-fit older adults, even subtle individual differences in CRF may influence the relationship between functional connectivity and aspects of cognition following a 6-month exercise intervention.

Feasibility and impact of a remote moderate-intensity yoga intervention on stress and executive functioning in working adults: a randomized controlled trial

The feasibility of a moderate-intensity yoga intervention, delivered remotely via supervised and unsupervised sessions, and its psychosocial and cognitive effects have not been thoroughly investigated. This randomized controlled trial assessed feasibility and preliminary efficacy of an 8-week moderate-intensity yoga intervention (3×/week, 50 min) delivered remotely (vs. a waitlist control arm), on stress and cognitive functioning. Participants (n = 86) were low active, full-time working adults (81.40% female; Mage = 41 years) with symptoms of stress. Feasibility was assessed via adherence, enjoyment, and safety; stress and anxiety via self-report questionnaires; and executive functioning via neuropsychological tests. Overall attendance was 75.1%, 100% of participants enjoyed the intervention, and only one adverse event was reported. At follow-up, the yoga group had significantly lower stress and anxiety, and higher accuracy on working memory tasks. Remote moderate intensity yoga practice proved safe, enjoyable, and may reduce stress and improve cognitive functioning. This study was pre-registered on ClinicalTrials.gov (NCT04740229).

Abstract P347: Measures of Microvascular Complications Varies Across Racial/Ethnic Groups Over a Seven Year Period: Post-Hoc Analysis of Action to Control Cardiovascular Risk in Diabetes (ACCORD) Trial Data

Introduction: Type 2 diabetes (T2D) microvascular complications is a major public health issue that disproportionately affects people of color in the U.S. and Canada. There is limited understanding of racial/ethnic disparities in the longitudinal natural history of microvascular complications. We aimed to address this gap in knowledge by examining racial/ethnic differences in microvascular complication-related measures over seven years among T2D adults living in the U.S. and Canada.

Hypothesis: We assessed the hypothesis that measures of microvascular complications vary by race/ethnic group over a period of seven years.

Methods: From 10,251 Action to Control Cardiovascular Risk in Diabetes (ACCORD) (2003-2009) trial participants, we derived 6,683 participants having a baseline and ≥ two years of outcome recordings for our analysis (baseline mean age 62 ± 6.6 years, and 11 ± 7.4 years of diabetes diagnosis). In this longitudinal study, we used T2D microvascular measurements recorded at baseline, yearly for seven years, and during a trial exit period. Neuropathy-related measures analyzed was the Michigan Neuropathy Screening Instrument (MNSI); Nephropathy-related measures included the glomerular filtration rate (eGFR) by four-variable Modification of Diet in Renal Disease equation (ml/min/1.73 m 2 ), urine albumin (mg/dl), and urine albumin : creatinine (mg/g). We examined differences in measurement among Black (n 1 = 1,176), White (n 2 = 4,282), and Other race adults (n 3 = 1,229). We used multigroup latent growth modeling to compare models from fully constrained to unconstrained means, covariances, and residual variances models.

Results: MNSI, eGFR, and urine albumin significantly differed across racial/ethnic groups (ΔX 2 MNSI (2) = 231.8, p<0.001; ΔX 2 eGFR (2) = 489.2, p<0.001; ΔX 2 urine-albumin (2) = 194.6, p<0.001). We noticed that at least one of the means and covariances differed across racial/ethnic groups. The average MNSI trajectory for Other race/ethnicity (intercept=1.88, slope=-0.08) were better than that for Black (intercept=2.07, slope=-0.09) and White adults (intercept=2.67, slope=-0.14). The average eGFR trajectories for Black (intercept=88.86, slope=-1.16) and Other race/ethnicity (intercept=85.68, slope=-1.15) were better than that for White adults (intercept=82.59, slope=-1.36). However, average urine albumin trajectories for Black adults were worst (intercept=10.77, slope=0.98) followed by Other race/ethnicity (intercept=9.36, slope=0.73) and White adults (intercept=7.65, slope=0.57).

Conclusion: Trajectories of microvascular complication-related measures appear to vary by racial/ethnic group. Other race adults, with primarily consists of Hispanics, appeared to at lower risk of neuropathy for years than Black and White adults. Nephropathy outcomes could vary across racial/ethnic group depending on how nephropathy is defined.

FEASIBILITY AND ACCEPTABILITY OF A HYBRID AEROBIC EXERCISE PROGRAM FOR OLDER ADULTS DURING THE COVID-19 PANDEMIC

The COVID-19 pandemic and ensuing lockdowns, physical distancing and mask mandates exacerbated the challenges older adults (OAs) face towards exercise engagement. We present data on the feasibility, safety, and acceptability of a hybrid (in-person and virtual) aerobic exercise program for OAs. Nf39 (30 females, Mage=64.10) low-active OAs completed an aerobics-based exercise program as part of a larger ongoing RCT. Participants exercised 3x/week by attending one in-person and two Zoom-based exercise classes. Attendance, attrition, format preferences, and adverse events were documented. Participants also completed an anonymous survey to detail their experiences with the hybrid delivery model. Thirty participants completed the program. Total average attendance of 83.64%; 58.93% and 24.71% of the attended sessions were on Zoom and in-person, respectively. On post-program surveys, 36.67% reported preferring Zoom sessions, followed by 33.33% preferring both formats equally. No adverse events were reported. From the anonymous program feedback surveys, common reasons for preferring the Zoom sessions included convenience; not having to wear a mask; not worrying about COVID exposure; and not feeling self-conscious about exercising with others. Commonly reported reasons for preferring the in-person sessions were increased motivation from group energy; social support; more space to move around; and better engagement with instructors. Collectively, these findings show a hybrid aerobic exercise program is feasible and safe for OAs to engage in and is overall well-accepted. Findings are encouraging for the design of future exercise programs for OAs, who continue to remain a vulnerable population during the pandemic but need a structure to remain sufficiently active.

CHANGES IN GENERAL SELF-EFFICACY FOLLOWING THE WITS WELLNESS PROGRAM: PRELIMINARY FINDINGS FROM THE 12-WEEK RCT

Self-efficacy among older adults has been associated with better sleep, increased vitality, decreased pain and discomfort as well as overall satisfaction with life. Interventions designed to increase general self-efficacy can therefore have wide-ranging effects on individual’s health as well as reduce the burden on healthcare systems. In this abstract we present preliminary data examining the impact of Wits Wellness on general self-efficacy among participants. Middle aged and older adults, Nf285 (Mean age 65.58 yrs, males=28) were randomized to either a Wits Wellness group or a Waitlist Control for 12-weeks. The 12-week wellness program addresses multiple factors including physical activity, stress, sleep, social isolation and diet with the goal of empowering older adults to make healthier lifestyle choices. At baseline and end of the 12-week trial, the 10-item PROMIS general self-efficacy scale was used to assess global self-efficacy which reflects a problem-solving approach despite perceived obstacles and challenges. Older participants aged 65 and above, who attended 8 or more weeks (Nf123, n=63 in Wits Wellness group) of the program demonstrated significant increases in their general self-efficacy. Results showed a significant group*time effect favoring the Wits Wellness intervention (F(1,120)=4.10, p=.045, partial eta2=.03). The intervention was most effective in boosting confidence among the older adults within the trial (>65 yrs.). These findings demonstrate preliminary efficacy of the Wits Wellness program and are significant as general self-efficacy is considered an important moderator of healthy adaptation to illness which is critical in old age. Funded by the Midwest Roybal Center grant P30AG022849.

EFFECTS OF A SIX-MONTH EXERCISE PROGRAM ON PHYSICAL ACTIVITY AMONG OLDER ADULTS WITH CHRONIC CONDITIONS

Health benefits of structured physical activity (PA) for older adults have been well documented. Older adults are highly impacted with major chronic conditions, leading to limitations in daily activities. This study examined the effects of an exercise program on moderate-vigorous physical activity (MVPA) and sedentary time after six months of exercise. Participants from a larger-ongoing trial were randomized into either yoga, aerobic or stretch-tone groups. A subsample of 58 participants was classified as chronic individuals (CI) based on presence of at least one chronic condition, and 31 as healthy individuals (HI), who completed accelerometer measures before and after the exercise program. A repeated measures analysis was performed to identify changes in PA over time for HI and CI. At both time-points, MVPA was significantly higher for HI. There was a significant increase in MVPA at month six for all participants, irrespective of health status. Mean MVPA in minutes for baseline HI: 153, CI: 98 and for month 6 HI: 188 CI: 116. There were no significant differences in sedentary time after the six-months of exercise. Although there was an increase in MVPA for HI and CI after structured exercise, no change was noted for sedentary time. Increased sedentary time has been proven to be a risk factor for poor health and although meeting criteria for MVPA is important, it is essential to address sedentary time in CI by implementing educational and interventional components that focus specifically on sedentary time. Funding: This data is from NCT04323163 funded by NIH-NIA – grant-AG066630.

EVALUATING THE FEASIBILITY AND ACCEPTABILITY OF THE WITS WELLNESS COGNITIVE HEALTH PROGRAM

About 11% of U.S. older adults are at risk for or have subjective cognitive decline. Although some factors that affect brain health cannot be changed, research indicates lifestyle changes (i.e., physical activity, social engagement, heart-healthy diet) can delay or reduce cognitive decline. Drawing from existing research, UI Extension developed Wits Wellness, a 12-week program designed to enhance brain health among people ages 50 and older. Wits Wellness addresses multiple factors that affect cognitive health (e.g., physical activity, stress, sleep, social isolation, diet). Using a two-arm randomized control trial, 285 participants (mean age = 66.6 years, 24 males) were randomly assigned to the Wits Wellness intervention (in person or virtual) or a waitlist control group. Summative program evaluation surveys indicated adherence to the intervention was high, with 68% of participants attending 9 or more of the 12 sessions. Program acceptability was high, with 82.7% evaluating the program as great to excellent, and 90.8% reporting great to excellent interaction with program leaders. Approximately 63.6% of participant write-in comments included positive statements about the program challenging their brains, and 59.1% indicated the program positively affected participants’ socialization. For program feasibility, 90.4% rated the 60-minute weekly sessions ‘just right’ for program length, while 66.3% rated the 12-week program duration ‘just right’ and 27.7% rated it ‘too long’. Thus, preliminary results suggest that Wits Wellness delivered both in-person and virtually was well attended and highly acceptable in the community setting. Future studies will examine the program’s efficacy in improving physical and mental health related outcomes.

Comparative assessment of ActiGraph data processing techniques for measuring sedentary behavior in adults with COPD

Objective.The ActiGraph is commonly used for measuring sedentary behavior (SB), but the best data processing technique is not established for sedentary adults with chronic illness. The purpose of this study was to process ActiGraph vertical axis and vector magnitude data with multiple combinations of filters, non-wear algorithm lengths, and cut-points and to compare ActiGraph estimates to activPAL-measured sedentary time in sedentary adults with chronic obstructive pulmonary disease (COPD).Approach.This study was a secondary analysis of adults ≥50 years (N = 59; mean age: 69.4 years;N = 31 males) with COPD. Participants woreActiGraph GT9XandactivPAL3for 7 d. ActiGraph vertical axis and vector magnitude data were processed using combinations of filters (normal, low frequency extension (LFE)), non-wear algorithm lengths (60, 90, 120 min), and cut-points for SB previously validated in older adults (two for vertical axis and three for vector magnitude data). The Bland-Altman method was used to assess concordance between sedentary time measured with 30 ActiGraph techniques and activPAL-measured sedentary time.Main results. Agreement between the two devices was moderate to strong for all techniques; concordance correlations ranged from 0.614 to 0.838. Limits of agreement were wide. The best overall technique was vector magnitude data with LFE filter, 120 min non-wear algorithm, and <40 counts/15 s SB cut-point (concordance correlation 0.838; mean difference -11.7 min d^-1).Significance. This analysis supports the use of ActiGraph vector magnitude data and LFE filter in adults with COPD, but also demonstrates that other techniques may be acceptable with appropriate cut-points. These results can guide ActiGraph data processing decisions.

Development of a Multicomponent Intervention to Initiate Health Behavior Change in Primary Care: The Kickstart Health Program

There is a growing movement to integrate behavioral health specialists into primary care settings in order to better manage patients' health behaviors. Group interventions in healthcare settings can provide services to multiple individuals simultaneously; however, the participants' experiences taking part in these activities and the logistics of integrating them into clinical settings are largely under-studied. This article describes the development and implementation of a novel group intervention for health behavior change, The Kickstart Health Program, which integrates components of cognitive, behavioral, acceptance, and experiential therapies. Participant feasibility, acceptability, experiences, and treatment course were assessed. Acceptability among a small sample of attendees was high, and initial data on behavior change suggest there were benefits to patients who attended the program. Increases in mindfulness practice and decreases in exercise barriers from baseline to 10-week follow-up were detected as were improvements in overall perceived health and well-being. Participants expressed that the program was acceptable and successful at helping them reach their individual health goals; however, enrollment barriers negatively impacted the feasibility of the program in regard to attendance. Modification to the enrollment process such as embedding referrals into the electronic medical record, encouraging spouse or family co-enrollment, and peer coaching may address these barriers. The Kickstart Health Program has the potential to improve health behaviors and paves the way for unique studies of dissemination and implementation of efficacious behavioral health interventions into real-world healthcare settings.

Can Light Physical Activity Improve Cognition Among Older Adults? A Scoping Review

Although the physical and cognitive benefits of moderate-vigorous intensity physical activity (MVPA) for older adults is well documented, this population often faces age-related functional and physical limitations impeding recommended MVPA participation. Recently, there has been a surge of interest in the independent health benefits of light-intensity physical activity (LPA) and its association with morbidity and mortality risk. LPA is the most common form of activity among older adults and its potential to combat cognitive aging needs to be investigated. The purpose of this scoping review was to catalog existing evidence on the association between device-based or technologically measured LPA and cognition among healthy older adults, identify trends in the literature, and pinpoint future areas of research. Six electronic databases were searched between January and August 2020. Eighteen published studies met the inclusion criteria: one acute exercise study, two randomized control trials (RCTs), twelve cross-sectional studies, and three longitudinal studies. Overall, n=9 studies (n=1 RCT, n=7 cross-sectional, and n=1 longitudinal) reported a significant, positive relationship between LPA and one or more cognitive outcomes including memory, attention, executive function and global cognition (MMSE/MOCA). These heterogeneous findings can largely be attributed to the diverse study designs, inconsistent definitions of LPA and numerous assessments used to test the cognitive domains. Collectively, these findings suggest LPA may be a potential lifestyle intervention to improve cognition among healthy older adults. However, the inconsistent approaches used among these studies suggests a more concerted, unified scientific approach and rigorous methodology are needed to further understand the LPA-cognition relationship.

White Matter Integrity Declined Over 6-Months, but Dance Intervention Improved Integrity of the Fornix of Older Adults

Degeneration of cerebral white matter (WM), or structural disconnection, is one of the major neural mechanisms driving age-related decline in cognitive functions, such as processing speed. Past cross-sectional studies have demonstrated beneficial effects of greater cardiorespiratory fitness, physical activity, cognitive training, social engagement, and nutrition on cognitive functioning and brain health in aging. Here, we collected diffusion magnetic resonance (MRI) imaging data from 174 older (age 60–79) adults to study the effects of 6-months lifestyle interventions on WM integrity. Healthy but low-active participants were randomized into Dance, Walking, Walking + Nutrition, and Active Control (stretching and toning) intervention groups (NCT01472744 on ClinicalTrials.gov). Only in the fornix there was a time × intervention group interaction of change in WM integrity: integrity declined over 6 months in all groups but increased in the Dance group. Integrity in the fornix at baseline was associated with better processing speed, however, change in fornix integrity did not correlate with change in processing speed. Next, we observed a decline in WM integrity across the majority of brain regions in all participants, regardless of the intervention group. This suggests that the aging of the brain is detectable on the scale of 6-months, which highlights the urgency of finding effective interventions to slow down this process. Magnitude of WM decline increased with age and decline in prefrontal WM was of lesser magnitude in older adults spending less time sedentary and more engaging in moderate-to-vigorous physical activity. In addition, our findings support the anterior-to-posterior gradient of greater-to-lesser decline, but only in the in the corpus callosum. Together, our findings suggest that combining physical, cognitive, and social engagement (dance) may help maintain or improve WM health and more physically active lifestyle is associated with slower WM decline. This study emphasizes the importance of a physically active and socially engaging lifestyle among aging adults.

White matter microstructure mediates the relationship between cardiorespiratory fitness and spatial working memory in older adults

White matter structure declines with advancing age and has been associated with a decline in memory and executive processes in older adulthood. Yet, recent research suggests that higher physical activity and fitness levels may be associated with less white matter degeneration in late life, although the tract-specificity of this relationship is not well understood. In addition, these prior studies infrequently associate measures of white matter microstructure to cognitive outcomes, so the behavioral importance of higher levels of white matter microstructural organization with greater fitness levels remains a matter of speculation. Here we tested whether cardiorespiratory fitness (VO2max) levels were associated with white matter microstructure and whether this relationship constituted an indirect pathway between cardiorespiratory fitness and spatial working memory in two large, cognitively and neurologically healthy older adult samples. Diffusion tensor imaging was used to determine white matter microstructure in two separate groups: Experiment 1, N=113 (mean age=66.61) and Experiment 2, N=154 (mean age=65.66). Using a voxel-based regression approach, we found that higher VO2max was associated with higher fractional anisotropy (FA), a measure of white matter microstructure, in a diverse network of white matter tracts, including the anterior corona radiata, anterior internal capsule, fornix, cingulum, and corpus callosum (PFDR-corrected<.05). This effect was consistent across both samples even after controlling for age, gender, and education. Further, a statistical mediation analysis revealed that white matter microstructure within these regions, among others, constituted a significant indirect path between VO2max and spatial working memory performance. These results suggest that greater aerobic fitness levels are associated with higher levels of white matter microstructural organization, which may, in turn, preserve spatial memory performance in older adulthood.

The influence of aerobic fitness on cerebral white matter integrity and cognitive function in older adults: results of a one-year exercise intervention

Cerebral white matter (WM) degeneration occurs with increasing age and is associated with declining cognitive function. Research has shown that cardiorespiratory fitness and exercise are effective as protective, even restorative, agents against cognitive and neurobiological impairments in older adults. In this study, we investigated whether the beneficial impact of aerobic fitness would extend to WM integrity in the context of a one-year exercise intervention. Further, we examined the pattern of diffusivity changes to better understand the underlying biological mechanisms. Finally, we assessed whether training-induced changes in WM integrity would be associated with improvements in cognitive performance independent of aerobic fitness gains. Results showed that aerobic fitness training did not affect group-level change in WM integrity, executive function, or short-term memory, but that greater aerobic fitness derived from the walking program was associated with greater change in WM integrity in the frontal and temporal lobes, and greater improvement in short-term memory. Increases in WM integrity, however, were not associated with short-term memory improvement, independent of fitness improvements. Therefore, while not all findings are consistent with previous research, we provide novel evidence for correlated change in training-induced aerobic fitness, WM integrity, and cognition among healthy older adults.

Cardiorespiratory fitness, hippocampal volume, and frequency of forgetting in older adults

OBJECTIVE

The purpose of this study was to extend our earlier work to determine the extent to which cardiorespiratory fitness is associated with the frequency of memory problems via its effects on the hippocampus and spatial working memory. We hypothesized that age, sex, education, body composition, and physical activity were direct determinants of fitness, which, in turn, influenced frequency of forgetting indirectly through hippocampal volume and spatial working memory.

METHOD

We conducted assessments of demographic characteristics, Body Mass Index (BMI), physical activity, cardiorespiratory fitness, hippocampal volume, spatial working memory, and frequency of forgetting in 158 older adults (M age = 66.49). Path analyses within a covariance modeling framework were used to examine relationships among these constructs.

RESULTS

Sex, age, BMI, and education were all significant determinants of cardiorespiratory fitness. The hypothesized path models for testing the effects of fitness on frequency of forgetting through hippocampal volume and accuracy and speed of spatial working memory all fit the data well.

CONCLUSIONS

Our findings suggest that older adults with higher levels of fitness show greater preservation of hippocampal volume, which, in turn, is associated with more accurate and faster spatial memory and fewer episodes of forgetting. Given the proportion of older adults reporting memory problems, it is necessary to determine whether improvements in fitness brought about by physical activity interventions can result in subsequent attenuation of memory problems or potentially in improvements in memory.

Physical activity, function, and quality of life: design and methods of the FlexToBa trial

The Flexibility, Toning, and Balance (FlexToBa) Trial is a two-armed randomized controlled trial which will contrast the effects of a DVD-delivered, home-based, physical activity intervention and a Healthy Aging attention control condition on physical activity, functional performance, functional limitations, and quality of life in low active, older adults. This innovative trial will recruit 300 participants across central Illinois who will be randomized into the intervention arm or control arm of the study. The intervention will last 6 months with a 6 month follow-up. Assessments at baseline, post intervention and follow-up will include physical activity (self-report and accelerometry), a battery of functional performance measures, functional limitations, quality of life, and an array of psychological health measures. In addition, measures of external validity will be included to determine public health significance of a successful outcome. Participants will engage in a progressive series of activities focusing on flexibility, strengthening, and balance exercises which are demonstrated by a trained exercise leader and age-appropriate models on a series of DVDs. Delivery of the intervention has its basis in social cognitive theory. The specific aims of the trial are (a) to determine the effects of the DVD-delivered FlexToBa program on physical activity, functional performance, functional limitations, and quality of life, (b) to examine the mediators of the relationships between physical activity and functional limitations and quality of life, (c) to assess external validity indicators relative to the intervention, and (d) to determine differential effects of the intervention on psychosocial health measures.

Growth trajectories of exercise self-efficacy in older adults: influence of measures and initial status

OBJECTIVE

This study examined differential trajectories of exercise-related self-efficacy beliefs across a 12-month randomized controlled exercise trial.

METHOD

Previously inactive older adults (N = 144; M age = 66.5) were randomly assigned to one of two exercise conditions (walking, flexibility-toning-balance) and completed measures of barriers self-efficacy (BARSE), exercise self-efficacy (EXSE), and self-efficacy for walking (SEW) across a 12-month period. Changes in efficacy were examined according to efficacy type and interindividual differences. Latent growth curve modeling was employed to (a) examine average levels and change in each type of efficacy for the collapsed sample and by intervention condition and (b) explore subpopulations (i.e., latent classes) within the sample that differ in their baseline efficacy and trajectory.

RESULTS

Analyses revealed two negative trends in BARSE and EXSE at predicted transition points, in addition to a positive linear trend in SEW. Two subgroups with unique baseline efficacy and trajectory profiles were also identified.

CONCLUSION

These results shed new light on the relationship between exercise and self-efficacy in older adults. They also highlight the need for strategies for increasing and maintaining efficacy within interventions, namely targeting participants who start with a disadvantage (lower efficacy) and integrating efficacy-boosting strategies for all participants prior to program end.

Non-Exercise Estimated Cardiorespiratory Fitness: Associations with Brain Structure, Cognition, and Memory Complaints in Older Adults

There is increasing evidence that cardiorespiratory fitness (CRF) is associated with brain structure and function, and improvements in CRF through exercise training have been associated with neural and cognitive functioning in older adults. The objectives of this study were to validate the use of a non-exercise estimate of CRF, and to examine its association with cognitive function, brain structure and subjective memory complaints. Low active, older adults (N = 86; M age= 65.14) completed a physician-supervised maximal exercise test, a 1-mile timed walk, several measures of cognitive function, and a 3 Tesla structural MRI. Fitness was also calculated from an equation derived by (Jurca et al., 2005) based on age, sex, body mass index, resting heart rate, and self-reported physical activity level. Analyses indicated that all three measures of CRF were significantly correlated with one another. In addition, measures of cognitive function, hippocampus volume, and memory complaints were significantly correlated with each measure of fitness. These findings have implications for using a low-risk, low-cost, non-exercise estimate of CRF in determining fitness associations with brain structure and cognitive function in older adults. As such, this measure may have utility for larger population based studies. Further validation is required, as is determination of whether such relationships hold over the course of exercise interventions.

Longitudinal invariance and construct validity of the abbreviated late-life function and disability instrument in healthy older adults

OBJECTIVE

To cross-validate the psychometric properties of the abbreviated Late-Life Function and Disability Instrument (LL-FDI), a measure of perceived functional limitations and disability.

DESIGN

Baseline and 12-month follow-up assessments conducted across the course of a 12-month exercise program.

SETTING

University research community.

PARTICIPANTS

Older healthy adults (N=179; mean ± SD age, 66.43±5.67y) at baseline; 145 were retained at follow-up.

INTERVENTIONS

Not applicable.

MAIN OUTCOME MEASURES

LL-FDI and functional performance measures.

RESULTS

Factor analyses confirmed the factor structure of the abbreviated LL-FDI, and all subscales met minimal criteria for temporal invariance. Significant correlations also were found between functional limitations subscales and an array of physical function performance measures, supporting the scale's construct validity.

CONCLUSIONS

The abbreviated LL-FDI with some modifications appears to be temporally invariant in community-dwelling older adults. Additionally, moderate relationships between functional limitations and functional performance provide further support for these being conceptually distinct constructs.

Self-efficacy: Implications for Physical Activity, Function, and Functional Limitations in Older Adults

Attenuating the physical decline and increases in disability associated with the aging process is an important public health priority. Evidence suggests that regular physical activity participation improves functional performance, such as walking, standing balance, flexibility, and getting up out of a chair, and also plays an important role in the disablement process by providing a protective effect against functional limitations. Whether these effects are direct or indirect has yet to be reliably established. In this review, the authors take the perspective that such relationships are indirect and operate through self-efficacy expectations. They first provide an introduction to social cognitive theory followed by an overview of self-efficacy's reciprocal relationship with physical activity. They then consider the literature that documents the effects of physical activity on functional performance and functional limitations in older adults and the extent to which self-efficacy might mediate these relationships. Furthermore, they also present evidence that suggests that self-efficacy plays a pivotal role in a model in which the protective effects conferred by physical activity on functional limitations operate through functional performance. The article concludes with a brief section making recommendations for the development of strategies within physical activity and rehabilitative programs for maximizing the major sources of efficacy information.

Plasticity of brain networks in a randomized intervention trial of exercise training in older adults

Research has shown the human brain is organized into separable functional networks during rest and varied states of cognition, and that aging is associated with specific network dysfunctions. The present study used functional magnetic resonance imaging (fMRI) to examine low-frequency (0.008 < f < 0.08 Hz) coherence of cognitively relevant and sensory brain networks in older adults who participated in a 1-year intervention trial, comparing the effects of aerobic and non-aerobic fitness training on brain function and cognition. Results showed that aerobic training improved the aging brain's resting functional efficiency in higher-level cognitive networks. One year of walking increased functional connectivity between aspects of the frontal, posterior, and temporal cortices within the Default Mode Network and a Frontal Executive Network, two brain networks central to brain dysfunction in aging. Length of training was also an important factor. Effects in favor of the walking group were observed only after 12 months of training, compared to non-significant trends after 6 months. A non-aerobic stretching and toning group also showed increased functional connectivity in the DMN after 6 months and in a Frontal Parietal Network after 12 months, possibly reflecting experience-dependent plasticity. Finally, we found that changes in functional connectivity were behaviorally relevant. Increased functional connectivity was associated with greater improvement in executive function. Therefore the study provides the first evidence for exercise-induced functional plasticity in large-scale brain systems in the aging brain, using functional connectivity techniques, and offers new insight into the role of aerobic fitness in attenuating age-related brain dysfunction.