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1.  White matter volume mediates the relationship between self-efficacy and mobility in older women 
Experimental aging research  2016;42(5):460-470.
With our aging population, understanding determinants of healthy aging is a priority. One essential component of healthy aging is mobility. While self-efficacy can directly impact mobility in older adults, it is unknown what role brain health may play in this relationship.
We conducted a cross-sectional pilot analysis of community-dwelling women (n = 80, mean age = 69 years) to examine whether brain volume mediates the relationship between falls-related self-efficacy, as measured by the Activities-specific Balance Confidence (ABC) scale, and mobility, as measured by the Timed Up and Go (TUG) test. Age, depression, education, functional comorbidities, and Montreal Cognitive Assessment (MoCA) were included in the model as covariates.
We report that total white matter volume, specifically, significantly mediates the relationship between self-efficacy and mobility, where higher self-efficacy was associated with greater white matter volume (r=0.28), which in turn, was associated with better mobility (r=−0.30).
Our pilot study extends our understanding of the psychosocial and neurological factors that contribute to mobility, and provides insight into effective strategies that may be used to improve functional independence among older adults. Future prospective and intervention studies are required to further elucidate the nature of the relationship between self-efficacy, mobility, and brain health.
PMCID: PMC5289890  PMID: 27749206 CAMSID: cams6536
Mobility; Self-efficacy; Aging; Brain health; White matter volume
2.  The Impact of Aerobic Exercise on Fronto-Parietal Network Connectivity and Its Relation to Mobility: An Exploratory Analysis of a 6-Month Randomized Controlled Trial 
Impaired mobility is a major concern for older adults and has significant consequences. While the widely accepted belief is that improved physical function underlies the effectiveness of targeted exercise training in improving mobility and reducing falls, recent evidence suggests cognitive and neural benefits gained through exercise may also play an important role in promoting mobility. However, the underlying neural mechanisms of this relationship are currently unclear. Thus, we hypothesize that 6 months of progressive aerobic exercise training would alter frontoparietal network (FPN) connectivity during a motor task among older adults with mild subcortical ischemic vascular cognitive impairment (SIVCI)—and exercise-induced changes in FPN connectivity would correlate with changes in mobility. We focused on the FPN as it is involved in top-down attentional control as well as motor planning and motor execution. Participants were randomized either to usual-care (CON), which included monthly educational materials about VCI and healthy diet; or thrice-weekly aerobic training (AT), which was walking outdoors with progressive intensity. Functional magnetic resonance imaging was acquired at baseline and trial completion, where the participants were instructed to perform bilateral finger tapping task. At trial completion, compared with AT, CON showed significantly increased FPN connectivity strength during right finger tapping (p < 0.05). Across the participants, reduced FPN connectivity was associated with greater cardiovascular capacity (p = 0.05). In the AT group, reduced FPN connectivity was significantly associated with improved mobility performance, as measured by the Timed-Up-and-Go test (r = 0.67, p = 0.02). These results suggest progressive AT may improve mobility in older adults with SIVCI via maintaining intra-network connectivity of the FPN.
PMCID: PMC5492161  PMID: 28713255
aging; impaired mobility; vascular cognitive impairment; fronto-parietal network; functional connectivity; fMRI
3.  The Neurocognitive Basis for Impaired Dual-Task Performance in Senior Fallers 
Falls are a major health-care concern, and while dual-task performance is widely recognized as being impaired in those at-risk for falls, the underlying neurocognitive mechanisms remain unknown. A better understanding of the underlying mechanisms could lead to the refinement and development of behavioral, cognitive, or neuropharmacological interventions for falls prevention. Therefore, we conducted a cross-sectional study with community-dwelling older adults aged 70–80 years with a history of falls (i.e., two or more falls in the past 12 months) or no history of falls (i.e., zero falls in the past 12 months); n = 28 per group. We compared functional activation during cognitive-based dual-task performance between fallers and non-fallers using functional magnetic resonance imaging (fMRI). Executive cognitive functioning was assessed via Stroop, Trail Making, and Digit Span. Mobility was assessed via the Timed Up and Go test (TUG). We found that non-fallers exhibited significantly greater functional activation compared with fallers during dual-task performance in key regions responsible for resolving dual-task interference, including precentral, postcentral, and lingual gyri. Further, we report slower reaction times during dual-task performance in fallers and significant correlations between level of functional activation and independent measures of executive cognitive functioning and mobility. Our study is the first neuroimaging study to examine dual-task performance in fallers, and supports the notion that fallers have reduced functional brain activation compared with non-fallers. Given that dual-task performance—and the underlying neural concomitants—appears to be malleable with relevant training, our study serves as a launching point for promising strategies to reduce falls in the future.
PMCID: PMC4746244  PMID: 26903862
falls risk; fallers; dual-task; fMRI; aging neuroscience
4.  Overall reductions in functional brain activation are associated with falls in older adults: an fMRI study 
Falls are a common geriatric condition, and while impaired cognitive function has been identified as a key risk factor, the neural correlates that contribute to reduced executive functioning and falls currently remain unknown. In this study, community-dwelling adults aged 65–75 years were divided into two groups based on their recent history of falls (fallers versus non-fallers). All participants completed the Flanker task during functional magnetic resonance imaging (fMRI). We examined the hemodynamic response of congruent and incongruent trials separately in order to separate the relative contribution of each trial type as a function of falls history. We found that fallers exhibited a smaller difference in functional activation between congruent and incongruent trials relative to non-fallers, as well as an overall reduction in level of blood-oxygen-level dependent response. Of particular note, the medial frontal gyrus – a region implicated in motor planning – demonstrated hypo-activation in fallers, providing evidence that the prefrontal cortex might play a central role in falls risk in older adults.
PMCID: PMC3867665  PMID: 24391584
falls; older adults; fMRI; executive cognitive functions; Flanker task; medial frontal gyrus
5.  Emerging Concept: ‘Central Benefit Model’ of Exercise in Falls Prevention 
Falls are a common geriatric syndrome and are the third leading cause of chonic disability worldwide. Falls are not random events and occur, at least in part, due to impaired physiological function, such as impaired balance, and cognitive impairment. The clinical syndrome of falls is important for sports and exercise medicine clinicians as there is Level 1 evidence that targeted exercise prescription is an effective intervention strategy. The widely accepted dogma is that improved physical function, balance and muscle strength, underlies the effectiveness of the exercise in reducing falls. However, findings from randomized controlled trials suggest that exercise reduce falls via mechanisms other than improved physiological function. We propose that improved cognitive function – specifically, executive functions – and associated functional plasticity may be an important yet under-appreciated mechanism by which the exercise reduces falls in older adults.
PMCID: PMC5226845  PMID: 22522589 CAMSID: cams6449
Executive Functions; Exercise; Falls
6.  Falls-related self-efficacy is independently associated with quality adjusted life years in older women 
Age and ageing  2011;40(3):340-346.
Falls-related self-efficacy is associated with falls, falls-related injury and subsequent functional decline which may lead to poor health related quality of life (HRQL). To our knowledge, no previous studies have examined the independent contribution of falls-related self-efficacy to HRQL. Our primary objective was to determine whether falls-related self-efficacy is independently associated HRQL, measured by Quality Adjusted Life Years (QALYs), in older women after accounting for known covariates.
We conducted a secondary analysis of 135 community-dwelling older women aged 65–75 years who participated in a 12-month randomized controlled trial of resistance training. We assessed falls-related self-efficacy using the Activities Specific Balance Confidence Scale and QALYs calculated from the EuroQol EQ-5D (EQ-5D).
Our multivariate linear regression model demonstrated that falls-related self-efficacy as assessed using the Activities Specific Balance Confidence Scale was independently associated with QALYs after accounting for age, group, education, functional comorbidity index, general mobility, global cognition and physiological falls risk. The final model explained 52% of the variation in QALYs. The ABC Scale accounted for an additional 5% of the total variance in the final model.
Although falls related self efficacy was independently associated with QALYs after controlling for a number of known variables, there may well be other factors not investigated, such as risk taking behaviour and psychological measures, which could account for some of the association.
Trial Registration Identifier: NCT00426881.
PMCID: PMC3990565  PMID: 21436152 CAMSID: cams2564
self-efficacy; quality adjusted life years; older women
7.  Exercise and Cognition in Older Adults: Is there a Role for Resistance Training Programs? 
In recent years, there has been a strong interest in physical activity as a primary behavioural prevention strategy against cognitive decline. A number of large prospective cohort studies have highlighted the protective role of regular physical activity in lowering the risk of cognitive impairment and dementia. The majority of prospective intervention studies of exercise and cognition to date have focused on aerobic-based exercise training. These studies highlight that aerobic-based exercise training enhances both brain structure and function. However, it has been suggested that other types of exercise training, such as resistance training, may also benefit cognition. The purpose of this brief review is to examine the evidence regarding resistance training and cognitive benefits. Three recent randomized exercise trials involving resistance training among seniors provide evidence that resistance training may have cognitive benefits. Resistance training may prevent cognitive decline among seniors via mechanisms involving IGF-1 and homocysteine. A side benefit of resistance training, albeit a very important one, is its established role in reducing morbidity among seniors. Resistance training specifically moderates the development of sarcopenia. The multifactorial deleterious sequelae of sarcopenia include increased falls and fracture risk as well as physical disability. Thus, clinicians should consider encouraging their clients to undertake both aerobic-based exercise training and resistance training not only for ‘physical health’ but also because of the almost certain benefits for ‘brain health’.
PMCID: PMC5298919  PMID: 19019904 CAMSID: cams6534
Resistance Training; Cognition; Older Adults
8.  Exercise is Medicine, For the Body and the Brain 
British journal of sports medicine  2014;48(12):943-944.
Dementia is one of the most pressing health care issues of the 21st century. Exercise is a modifiable lifestyle factor that has been identified as positively impacting cognitive functioning across the lifespan. Despite surmounting evidence linking exercise and cognitive functions in older adults, there is reluctance to adopt exercise as a prevention strategy; this view has been partially fueled by published reviews that have failed to include all the relevant literature. Therefore, in this commentary, we provide an update on the recent converging neuroimaging, behavioural, and biomarker evidence linking exercise with cognitive and brain health. We highlight that endorsing exercise as an effective strategy for improving health and well-being among older adults may potentially have a high impact for mitigating multiple health concerns, and should therefore be considered as a leading treatment strategy for dementia prevention.
PMCID: PMC4330095  PMID: 24659507 CAMSID: cams4566
Exercise; Physical activity; Cognition; Brain health; Aging
9.  Mind-wandering and falls risk in older adults 
Psychology and aging  2013;28(3):685-691.
While mind-wandering is common, engaging in task-irrelevant thoughts can have negative functional consequences. We examined whether mind-wandering frequency may be related to falls – a major health care problem. Seniors completed a sustained attention task and self-reported their current attentional states. Monthly falls reports were collected over 12 months. Falls were associated with an increased frequency of mind-wandering. Additionally, poorer performance on the sustained attention task was associated with more falls over 12 months. Given that fallers are known to have impaired executive cognitive functioning, our results are consistent with the current theory that poor attentional control may contribute to the occurrence of mind-wandering.
PMCID: PMC4357518  PMID: 24041001 CAMSID: cams4312
Aging; Mind-wandering; Falls
10.  Altered visual-spatial attention to task-irrelevant information is associated with falls risk in older adults 
Neuropsychologia  2013;51(14):3025-3032.
Executive cognitive functions play a critical role in falls risk – a pressing health care issue in seniors. In particular, intact attentional processing is integral for safe mobility and navigation. However, the specific contribution of impaired visual-spatial attention in falls remains unclear. In this study, we examined the association between visual-spatial attention to task-irrelevant stimuli and falls risk in community-dwelling older adults. Participants completed a visual target discrimination task at fixation while task-irrelevant probes were presented in both visual fields. We assessed attention to left and right peripheral probes using event-related potentials (ERPs). Falls risk was determined using the valid and reliable Physiological Profile Assessment (PPA). We found a significantly positive association between reduced attentional facilitation, as measured by the N1 ERP component, and falls risk. This relationship was specific to probes presented in the left visual field and measured at ipsilateral electrode sites. Our results suggest that fallers exhibit reduced attention to the left side of visual space and provide evidence that impaired right hemispheric function and/or structure may contribute to falls.
PMCID: PMC4318690  PMID: 24436970 CAMSID: cams4313
Visual-spatial attention; Aging; Older adults; Falls risk; Event-related potentials (ERPs); Neuroimaging
11.  Resting State Default Mode Network Connectivity, Dual Task Performance, Gait Speed, and Postural Sway in Older Adults with Mild Cognitive Impairment 
Aging is associated with an increased risk of falling. In particular, older adults with mild cognitive impairment (MCI) are more vulnerable to falling compared with their healthy counterparts. Major contributors to this increased falls risk include a decline in dual task performance, gait speed, and postural sway. Recent evidence highlights the potential influence of the default mode network (DMN), the frontoparietal network (FPN), and the supplementary motor area (SMA) on dual task performance, gait speed, and postural sway. The DMN is active during rest and deactivates during task-oriented processes, to maintain attention and stay on task. The FPN and SMA are involved in top-down attentional control, motor planning, and motor execution. The DMN shows less deactivation during task in older adults with MCI. This lack of deactivation is theorized to increase competition for resources between the DMN and task-related brain regions (e.g., the FPN and SMA), increasing distraction from the task and reducing task performance. However, no study has yet investigated the relationship between the between-network connectivity of the DMN with these regions and dual task walking, gait speed or postural sway. We hypothesized that greater functional connectivity both within the DMN and between DMN–FPN and DMN–SMA, will be associated with poorer performance during dual task walking, slower gait speed, and greater postural sway in older adults with MCI. Forty older adults with MCI were measured on a dual task-walking paradigm, gait speed over a 4-m walk, and postural sway using a sway-meter. Greater within-DMN connectivity was significantly correlated with poorer dual task performance. Furthermore, greater inter-network connectivity between the DMN and SMA was significantly correlated with slower gait speed and greater postural sway on the eyes open floor sway task. Thus, greater resting state DMN functional connectivity may be an underlying neural mechanism for reduced dual task ability, slower gait speed, and greater postural sway, resulting in the increased risk of mobility disability and falling in older adults with MCI.
PMCID: PMC5742581
functional connectivity; default mode network; dual task; gait speed; postural sway; mild cognitive impairment
12.  Measuring physical activity in older adults: calibrating cut-points for the MotionWatch 8© 
Given the world’s aging population, the staggering economic impact of dementia, the lack of effective treatments, and the fact a cure for dementia is likely many years away – there is an urgent need to develop interventions to prevent or at least delay dementia’s progression. Thus, lifestyle approaches to promote healthy aging are an important line of scientific inquiry. Good sleep quality and physical activity (PA) are pillars of healthy aging, and as such, are an increasing focus for intervention studies aimed at promoting health and cognitive function in older adults. However, PA and sleep quality are difficult constructs to evaluate empirically. Wrist-worn actigraphy (WWA) is currently accepted as a valid objective measure of sleep quality. The MotionWatch 8© (MW8) is the latest WWA, replacing the discontinued Actiwatch 4 and Actiwatch 7. In the current study, concurrent measurement of WWA and indirect calorimetry was performed during 10 different activities of daily living for 23 healthy older adults (aged 57–80 years) to determine cut-points for sedentary and moderate-vigorous PA – using receiver operating characteristic curves – with the cut-point for light activity being the boundaries between sedentary and moderate to vigorous PA. In addition, simultaneous multi-unit reliability was determined for the MW8 using inter-class correlations. The current study is the first to validate MW8 activity count cut-points – for sedentary, light, and moderate to vigorous PA – specifically for use with healthy older adults. These cut-points provide important context for better interpretation of MW8 activity counts, and a greater understanding of what these counts mean in terms of PA. Hence, our results validate another level of analysis for researchers using the MW8 in studies aiming to examine PA and sleep quality concurrently in older adults.
PMCID: PMC4548198  PMID: 26379546
accelerometers; actigraphy; indirect calorimeters; validation; physical activity; older adults
13.  Improvements to executive function during exercise training predict maintenance of physical activity over the following year 
Previous studies have shown that exercise training benefits cognitive, neural, and physical health markers in older adults. It is likely that these positive effects will diminish if participants return to sedentary lifestyles following training cessation. Theory posits that that the neurocognitive processes underlying self-regulation, namely executive function (EF), are important to maintaining positive health behaviors. Therefore, we examined whether better EF performance in older women would predict greater adherence to routine physical activity (PA) over 1 year following a 12-month resistance exercise training randomized controlled trial. The study sample consisted of 125 community-dwelling women aged 65–75 years old. Our primary outcome measure was self-reported PA, as measured by the Physical Activity Scale for the Elderly (PASE), assessed on a monthly basis from month 13 to month 25. Executive function was assessed using the Stroop Test at baseline (month 0) and post-training (month 12). Latent growth curve analyses showed that, on average, PA decreased during the follow-up period but at a decelerating rate. Women who made greater improvements to EF during the training period showed better adherence to PA during the 1-year follow-up period (β = −0.36, p < 0.05); this association was unmitigated by the addition of covariates (β = −0.44, p < 0.05). As expected, EF did not predict changes in PA during the training period (p > 0.10). Overall, these findings suggest that improving EF plays an important role in whether older women maintain higher levels of PA following exercise training and that this association is only apparent after training when environmental support for PA is low.
PMCID: PMC4034407  PMID: 24904387
executive function; aging; physical activity adherence; exercise training; temporal self-regulation theory
14.  Exercise Training and Recreational Activities to Promote Executive Functions in Chronic Stroke: A Proof-of-Concept Study 
Stroke survivors represent a target population in need of intervention strategies to promote cognitive function and prevent dementia. Both exercise and recreational activities are promising strategies. We assessed the effect of a six-month exercise and recreation program on executive functions in adults with chronic stroke.
A six-month ancillary study within a multi-centre randomized trial. Twenty-eight chronic stroke survivors (i.e., ≥ 12 months since an index stroke) were randomized to one of two experimental groups: intervention (INT; n=12) or delayed intervention (D-INT; n=16). Participants of the INT group received a six-month community-based structured program that included two sessions of exercise training and one session of recreation and leisure activities per week. Participants of the D-INT group received usual care. The primary outcome measure was the Stroop Test, a cognitive test of selective attention and conflict resolution. Secondary cognitive measures included set shifting and working memory. Mood, functional capacity, and general balance and mobility were additional secondary outcome measures.
Compared with the D-INT group, the INT group significantly improved selective attention and conflict resolution (p=0.02), working memory (p=0.04), and functional capacity (p=0.02) at the end of the six-month intervention period. Improved selective attention and conflict resolution was significantly associated with functional capacity at six months (r=0.39; p=0.04).
This is the first randomized study to demonstrate that an exercise and recreation program can significantly benefit executive functions in community-dwelling chronic stroke survivors who are mildly cognitively impaired – a population at high-risk for dementia and functional decline. Thus, clinicians should consider prescribing exercise and recreational activities in the cognitive rehabilitation of chronic stroke survivors.
Clinical Trial Registration Unique identifier: NCT01085240.
PMCID: PMC4486380  PMID: 25440324 CAMSID: cams4837
Exercise; Socialization; Executive Functions; Chronic Stroke
15.  Challenges with cost-utility analyses of behavioral interventions among older adults at risk for dementia 
British journal of sports medicine  2013;10.1136/bjsports-2013-092743.
Cognitive decline is one of the most prominent health care issues of the 21st century. Within the context of combating cognitive decline through behavioural interventions, physical activity is a promising approach. There is a dearth of health economic data in the area of behavioural interventions for dementia prevention. Yet, economic evaluations are essential for providing information to policy makers for resource allocation. It is essential we first address population and intervention specific methodological challenges prior to building a larger evidence base. We use a cost-utility analysis conducted alongside the Exercise for Cognition and Everyday Living (EXCEL) study to illustrate methodological challenges specific to assessing the cost-effectiveness of behavioural interventions aimed at older adults at risk of cognitive decline.
A cost-utility analysis conducted concurrently with a six-month three arm randomized controlled trial (i.e., the EXCEL study) was used as an example to identify and discuss methodological challenges.
Both the aerobic training and resistance training interventions were less costly than twice weekly balance and tone classes. In critically evaluating the economic evaluation of the EXCEL study we identified four category specific challenges: 1) Analyzing costs, 2) Assessing QALYs 3) Incomplete data and 4) ‘Intervention’ activities of the control group.
Resistance training and aerobic training resulted in health care cost saving and were equally effective to balance and tone classes after only 6 months of intervention. To ensure this population is treated fairly in terms of claims on resources, we first need to identify areas for methodological improvement.
PMCID: PMC4318691  PMID: 24195918 CAMSID: cams4287
cost-utility analysis; older adults; dementia; mild cognitive impairment
16.  Are the cognitive and economic benefits of resistance training sustained among community-dwelling senior women: A one-year follow-up study of the Brain Power study 
Archives of internal medicine  2010;170(22):2036-2038.
PMCID: PMC4516402  PMID: 21149764 CAMSID: cams4894
Resistance Training; Executive Functions; Older Adults; Economic Evaluation
17.  Aerobic Exercise Increases Hippocampal Volume in Older Women with Probable Mild Cognitive Impairment: A 6-Month Randomized Controlled Trial 
Mild cognitive impairment (MCI) is a well-recognized risk factor for dementia and represents a vital opportunity for intervening. Exercise is a promising strategy for combating cognitive decline, by improving both brain structure and function. Specifically, aerobic training (AT) improved spatial memory and hippocampal volume in healthy community-dwelling older adults. In older women with probable MCI, we previously demonstrated that both resistance training (RT) and AT improved memory. In this secondary analysis, we investigated: 1) the effect of both RT and AT on hippocampal volume; and 2) the association between change in hippocampal volume and change in memory.
Eighty-six females aged 70 to 80 years with probable MCI were randomly assigned to a six-month, twice-weekly program of: 1) AT, 2) RT, or 3) Balance and Tone Training (BAT; i.e., control). At baseline and trial completion, participants performed a 3T magnetic resonance imaging scan to determine hippocampal volume. Verbal memory and learning was assessed by Rey’s Auditory Verbal Learning Test.
Compared with the BAT group, AT significantly improved left, right, and total hippocampal volumes (p≤0.03). After accounting for baseline cognitive function and experimental group, increased left hippocampal volume was independently associated with reduced verbal memory and learning performance as indexed by loss after interference (r=0.42, p=0.03).
Aerobic training significantly increased hippocampal volume in older women with probable MCI. More research is needed to ascertain the relevance of exercise-induced changes in hippocampal volume on memory performance in older adults with MCI.
PMCID: PMC4508129  PMID: 24711660 CAMSID: cams4891
Mild cognitive impairment; aerobic exercise; memory; hippocampus; brain volume
18.  Examining the relationship between specific cognitive processes and falls risk in older adults: a systematic review 
Recent evidence suggests that impaired cognition increases seniors’ risk of falling. The purpose of this review was to identify the cognitive domains that are significantly associated with falls or falls risk in older adults.
We conducted a systematic review of peer-reviewed journal articles published from 1948 to present, focusing on studies investigating different domains of cognitive function and their association with falls or falls risk in adults aged 60 years or older. In accordance with Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) guidelines, we completed a comprehensive search of MEDLINE, Pubmed, and EMBASE databases to identify studies examining the association between cognitive function and falls or falls risk. With an expert in the field, we developed a quality assessment questionnaire to rate the quality of the studies included in this systematic review.
Twenty-five studies were included in the review. We categorized studies based on two related but distinct cognitive domains: 1) executive functions, or 2) dual-task ability. Twelve studies reported a significant association between executive functions and falls risk. Thirteen studies reported that dual-task performance is a predictor of falls or falls risk in older adults. Three studies did not report an association between cognition and falls risk.
Consistent evidence demonstrated that executive functions and dual-task performance were highly associated with falls or falls risk. The results from this review will aid healthcare professionals and researchers in developing innovative screening and treatment strategies for mitigating falls risk by targeting specific cognitive domains.
PMCID: PMC4476839  PMID: 22638707 CAMSID: cams2568
falls; systematic review; cognition; executive function; older adults
19.  Self-efficacy is independently associated with brain volume in older women 
Age and ageing  2012;41(4):495-501.
Aging is highly associated with neurodegeneration and atrophy of the brain. Evidence suggests that personality variables are risk factors for reduced brain volume. We examine whether falls-related self-efficacy is independently associated with brain volume.
A cross-sectional analysis of whether falls-related self-efficacy is independently associated with brain volumes (total, grey, and white matter). Three multivariate regression models were constructed. Covariates included in the models were age, global cognition, systolic blood pressure, functional comorbidity index, and current physical activity level. MRI scans were acquired from 79 community-dwelling senior women aged 65 to 75 years old. Falls-related self-efficacy was assessed by the Activities Specific Balance Confidence (ABC) Scale.
After accounting for covariates, falls-related self-efficacy was independently associated with both total brain volume and total grey matter volume. The final model for total brain volume accounted for 17% of the variance, with the ABC score accounting for 8%. For total grey matter volume, the final model accounted for 24% of the variance, with the ABC score accounting for 10%.
We provide novel evidence that falls-related self-efficacy, a modifiable risk factor for healthy aging, is positively associated with total brain volume and total grey matter volume.
Trial Registration Identifier: NCT00426881.
PMCID: PMC4461373  PMID: 22436405 CAMSID: cams4718
self-efficacy; brain volume; older women
20.  Elevated body mass index and maintenance of cognitive function in late life: exploring underlying neural mechanisms 
Background: Obesity is associated with vascular risk factors that in turn, may increase dementia risk. However, higher body mass index (BMI) in late life may be neuroprotective. The possible neural mechanisms underlying the benefit of higher BMI on cognition in older adults are largely unknown. Thus, we used functional connectivity magnetic resonance imaging (fcMRI) to examine: (1) the relationship between BMI and functional brain connectivity; and (2) the mediating role of functional brain connectivity in the association between baseline BMI and change in cognitive function over a 12-month period.
Methods:We conducted a 12-month, prospective study among 66 community-dwelling older adults, aged 70 to 80 years, who were categorized as: normal weight (BMI from 18.50 to 24.99); overweight (BMI from 25.00 to 29.99); and obese (BMI ≥ 30.00). At baseline, participants performed a finger-tapping task during fMRI scanning. Relevant neural networks were initially identified through independent component analysis (ICA) and subsequently examined through seed-based functional connectivity analysis. At baseline and 12-months, we measured three executive cognitive processes: (1) response inhibition; (2) set shifting; and (3) working memory.
Results:Obese individuals showed lower task-related functional connectivity during finger tapping in the default mode network (DMN) compared with their healthy weight counterparts (p < 0.01). Lower task-related functional connectivity in the DMN at baseline was independently associated with better working memory performance at 12-months (p = 0.02). Finally, DMN functional connectivity during finger tapping significantly mediated the relationship between baseline BMI and working memory at 12-months (indirect effect: −0.155, 95% confidence interval [−0.313, −0.053]).
Conclusions:These findings suggest that functional connectivity of the DMN may be an underlying mechanism by which higher BMI confers protective effects to cognition in late life.
PMCID: PMC4539697  PMID: 26347646
older adults; default mode network (DMN); mediation analysis; executive functions; body mass index
21.  Measuring sleep quality in older adults: a comparison using subjective and objective methods 
Sleep quality decreases with aging and thus sleep complaints are prevalent in older adults, particularly for those with cognitive impairment and dementia. For older adults, emerging evidence suggests poor sleep quality increases risk of developing cognitive impairment and dementia. Given the aging population—and the impending economic burden associated with increasing numbers of dementia patients—there is pressing need to improve sleep quality among older adults. As such, research efforts have increased focus on investigating the association between age-related sleep changes and cognitive decline in older adults. Sleep quality is a complex construct to evaluate empirically, and yet the Pittsburg Sleep Quality Index (PSQI) is commonly used in studies as their only measure of sleep quality. Furthermore, the PSQI may not be the best sleep quality measure for older adults, due to its reliance on the cognitive capacity to reflect on the past month. Further study is needed to determine the PSQI's validity among older adults. Thus, the current study examined sleep quality for 78 community dwelling adults 55+ to determine the PSQI's predictive validity for objective sleep quality (as measured by actigraphy). We compared two subjective measures of sleep quality—the PSQI and Consensus Sleep Diary (CSD)—with actigraphy (MotionWatch 8©; camntech). Our results suggest perceived sleep quality is quite different from objective reality, at least for adults 55+. Importantly, we show this difference is unrelated to age, gender, education, or cognitive status (assessed using standard screens). Previous studies have shown the PSQI to be a valuable tool for assessing subjective sleep quality; however, our findings indicate for older adults the PSQI should not be used as a substitute for actigraphy, or vice versa. Hence, we conclude best practice is to include both subjective and objective measures when examining sleep quality in older adults (i.e., the PSQI, CSD, and actigraphy).
PMCID: PMC4561455  PMID: 26441633
circadian; sleep; aging; actigraphy; Pittsburg Sleep Quality Index; Consensus Sleep Diary; mild cognitive impairment; dementia
22.  Cognitive status is a determinant of health resource utilization among individuals with a history of falls: a 12-month prospective cohort study 
Although falls are costly there are no prospective data examining factors among fallers that drive health care resource utilization. We identified key determinants of health resource utilization (HRU) at 6 and 12 months among older adults with a history of falls. Specifically, with the increasing recognition that cognitive impairment is associated with increased falls risk, we investigated cognition as a potential driver of health resource utilisation.
This 12-month prospective cohort study at the Vancouver Falls Prevention Clinic (n=319) included participants with a history of at least one fall in the previous 12 months. Based on their cognitive status, participants were divided into two groups: 1) No Mild Cognitive Impairment (MCI) and 2) MCI. We constructed two linear regression models with HRU at 6 and 12 months as the dependent variables for each model, respectively. Predictors relating to mobility, global cognition, executive functions and cognitive status (MCI versus no MCI) were examined. Age, sex, comorbidities, depression status and activities of daily living were included regardless of statistical significance.
Global cognition, comorbidities, working memory and cognitive status (MCI versus no MCI ascertained using the MoCA) were significant determinants of total HRU at 6 months. The number of medical comorbidities and global cognition were significant determinants of total HRU at 12 months.
MCI status was a determinant of HRU at 6 months among older adults with a history of falls. As such, efforts to minimize health care resource use related to falls, it is important to tailor future interventions to be effective for people with MCI who fall.
Trial Registration Identifier: NCT01022866
PMCID: PMC4898957  PMID: 26449355 CAMSID: cams5759
falls; cost; health resource utilization; older adults
23.  Sustained economic benefits of resistance training among community-dwelling senior women 
Previously, we demonstrated that 12 months of group based resistance training intervention delivered once or twice weekly provided significantly lower healthcare resource utilization costs and health benefits including improvement in health related quality of life than balance and tone exercises.
We conducted a 12-month follow-up study to determine whether these health and cost benefits of resistance training were sustained 12 months after formal cessation of the intervention.
Cost-utility analysis conducted alongside a randomized controlled trial.
Community-dwelling women aged 65 to 75 years living in Vancouver, British Columbia.
123 of the 155 community-dwelling women aged 65 to 75 years who originally were randomly allocated to once-weekly resistance training (n=54), twice-weekly resistance training (n=52), or to twice-weekly balance and tone exercises (i.e., control group) (n=49) participated in the 12-month follow-up study. Of these, 98 took part in the economic evaluation (twice-weekly balance and tone exercises, n=28, once-weekly resistance training, n=35; twice-weekly resistance training, n=35).
Our primary outcome measure was incremental cost per quality adjusted life year (QALY) gained. Healthcare resource utilization was assessed over 21 months (2009 prices); health status was assessed using the EQ-5D to calculate QALYs using a 21 month time horizon.
Once- and twice-weekly resistance training were less costly than balance and tone classes with incremental mean healthcare costs of Canadian dollars (CAD$) -$1857 and -$1077, respectively. The incremental QALYs for once- and twice weekly resistance training were -0.051 and -0.081, respectively, compared with balance and tone exercises.
The cost benefits of participating in a 12-month resistance training intervention were sustained for both the once- and twice-weekly resistance training group while the health benefits were not.
PMCID: PMC4019577  PMID: 21718265 CAMSID: cams2567
quality adjusted life year; executive functions; cognition; older adults; cost-utility analysis
24.  Guidelines for Assessment of Gait and Reference Values for Spatiotemporal Gait Parameters in Older Adults: The Biomathics and Canadian Gait Consortiums Initiative 
Background: Gait disorders, a highly prevalent condition in older adults, are associated with several adverse health consequences. Gait analysis allows qualitative and quantitative assessments of gait that improves the understanding of mechanisms of gait disorders and the choice of interventions. This manuscript aims (1) to give consensus guidance for clinical and spatiotemporal gait analysis based on the recorded footfalls in older adults aged 65 years and over, and (2) to provide reference values for spatiotemporal gait parameters based on the recorded footfalls in healthy older adults free of cognitive impairment and multi-morbidities.
Methods: International experts working in a network of two different consortiums (i.e., Biomathics and Canadian Gait Consortium) participated in this initiative. First, they identified items of standardized information following the usual procedure of formulation of consensus findings. Second, they merged databases including spatiotemporal gait assessments with GAITRite® system and clinical information from the “Gait, cOgnitiOn & Decline” (GOOD) initiative and the Generation 100 (Gen 100) study. Only healthy—free of cognitive impairment and multi-morbidities (i.e., ≤ 3 therapeutics taken daily)—participants aged 65 and older were selected. Age, sex, body mass index, mean values, and coefficients of variation (CoV) of gait parameters were used for the analyses.
Results: Standardized systematic assessment of three categories of items, which were demographics and clinical information, and gait characteristics (clinical and spatiotemporal gait analysis based on the recorded footfalls), were selected for the proposed guidelines. Two complementary sets of items were distinguished: a minimal data set and a full data set. In addition, a total of 954 participants (mean age 72.8 ± 4.8 years, 45.8% women) were recruited to establish the reference values. Performance of spatiotemporal gait parameters based on the recorded footfalls declined with increasing age (mean values and CoV) and demonstrated sex differences (mean values).
Conclusions: Based on an international multicenter collaboration, we propose consensus guidelines for gait assessment and spatiotemporal gait analysis based on the recorded footfalls, and reference values for healthy older adults.
PMCID: PMC5540886
gait; aged; guidelines; reference values
25.  Corrigendum: The Impact of Aerobic Exercise on Fronto-Parietal Network Connectivity and Its Relation to Mobility: An Exploratory Analysis of a 6-Month Randomized Controlled Trial 
PMCID: PMC5591871  PMID: 28900392
aging; impaired mobility; vascular cognitive impairment; fronto-parietal network; functional connectivity; fMRI

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