Four weeks of meditation training improves sustained attention in community-dwelling older adults: a proof-of-concept randomized controlled trial

Introduction: With our rapidly expanding population of older adults, identifying effective intervention strategies to improve cognitive functioning is an increasing priority. This study sought to examine whether 4 weeks of thrice-weekly meditation training can improve attention in older adults, as well as whether such benefits may extend to other domains of cognition as well as mobility. Methods: Forty-three participants (mean age 68 years) were randomized into either the focused attention meditation group or the music listening control group (Clinicaltrials.gov ID NCT03417635). Participants completed three 20-minute guided group sessions per week for four consecutive weeks. Our primary outcome measure was behavioural performance on the Sustained Attention to Response Task (SART). Secondary and tertiary outcome measures included event-related potentials (ERPs) during the SART task, measures of executive functioning, and measures of mobility. Results: We found that meditation training significantly improved attention, as demonstrated by improved SART accuracy and changes in N2 ERP amplitude and latency. Discussion: These findings suggest that meditation may lead to changes in attention and underlying cognitive processing in older adults, although a full-scale definitive trial is needed. Future research on the long-term benefits with real world applications is warranted.

Combining exercise with cognitive training and vitamin D3 to improve functional brain connectivity (FBC) in older adults with mild cognitive impairment (MCI). Results from the SYNERGIC trial

Changes in functional brain connectivity (FBC) may indicate how lifestyle modifications can prevent the progression to dementia; FBC identifies areas that are spatially separate but temporally synchronized in their activation and is altered in those with mild cognitive impairment (MCI), a prodromal state between healthy cognitive aging and dementia. Participants with MCI were randomly assigned to one of five study arms. Three times per week for 20-weeks, participants performed 30-min of (control) cognitive training, followed by 60-min of (control) physical exercise. Additionally, a vitamin D₃ (10,000 IU/pill) or a placebo capsule was ingested three times per week for 20-weeks. Using the CONN toolbox, we measured FBC change (Post-Pre) across four statistical models that collapsed for and/or included some or all study arms. We conducted Pearson correlations between FBC change and changes in physical and cognitive functioning. Our sample included 120 participants (mean age: 73.89 ± 6.50). Compared to the pure control, physical exercise (model one; p-False Discovery Rate (FDR) < 0.01 & < 0.05) with cognitive training (model two; p-FDR =  < 0.001), and all three interventions combined (model four; p-FDR =  < 0.01) demonstrated an increase in FBC between regions of the Default-Mode Network (i.e., hippocampus and angular gyrus). After controlling for false discovery rate, there were no significant correlations between change in connectivity and change in cognitive or physical function. Physical exercise alone appears to be as efficacious as combined interventional strategies in altering FBC, but implications for behavioral outcomes remain unclear.

What do functional neuroimaging studies tell us about the association between falls and cognition in older adults? A systematic review

Impaired cognition is a known risk factor for falls in older adults. To enhance prevention strategies and treatment of falls among an aging global population, an understanding of the neural processes and networks involved is required. We present a systematic review investigating how functional neuroimaging techniques have been used to examine the association between falls and cognition in seniors. Peer-reviewed articles were identified through searching five electronic databases: 1) Medline, 2) PsycINFO, 3) CINAHL, 4) EMBASE, and 5) Pubmed. Key author, key paper, and reference searching was also conducted. Nine studies were included in this review. A questionnaire composed of seven questions was used to assess the quality of each study. EEG, fMRI, and PET were utilized across studies to examine brain function in older adults. Consistent evidence demonstrates that cognition is associated with measures of falls/falls risk, specifically visual attention and executive function. Our results show that falls/falls risk may be implicated with specific brain regions and networks. Future studies should be prospective and long-term in nature, with standardized outcome measures. Mobile neuroimaging techniques may also provide insight into brain activity as it pertains to cognition and falls in older adults in real-world settings.

Reshaping the path of mild cognitive impairment by refining exercise prescription: a study protocol of a randomized controlled trial to understand the "what," "for whom," and "how" of exercise to promote cognitive function

Background

Targeted exercise training is a promising strategy for promoting cognitive function and preventing dementia in older age. Despite the utility of exercise as an intervention, variation still exists in exercise-induced cognitive gains and questions remain regarding the type of training (i.e., what), as well as moderators (i.e., for whom) and mechanisms (i.e., how) of benefit. Both aerobic training (AT) and resistance training (RT) enhance cognitive function in older adults without cognitive impairment; however, the vast majority of trials have focused exclusively on AT. Thus, more research is needed on RT, as well as on the combination of AT and RT, in older adults with mild cognitive impairment (MCI), a prodromal stage of dementia. Therefore, we aim to conduct a 6-month, 2 × 2 factorial randomized controlled trial in older adults with MCI to assess the individual effects of AT and RT, and the combined effect of AT and RT on cognitive function and to determine the possible underlying biological mechanisms.

Methods

Two hundred and sixteen community-dwelling adults, aged 65 to 85 years, with MCI from metropolitan Vancouver will be recruited to participate in this study. Randomization will be stratified by biological sex and participants will be randomly allocated to one of the four experimental groups: (1) 4×/week balance and tone (BAT; i.e., active control); (2) combined 2×/week AT + 2×/week RT; (3) 2×/week AT + 2×/week BAT; or (4) 2×/week RT + 2×/week BAT. The primary outcome is cognitive function as measured by the Alzheimer’s Disease Assessment Scale-Cognitive-Plus. Secondary outcomes include cognitive function, health-related quality of life, physical function, actigraphy measures, questionnaires, and falls. Outcomes will be measured at baseline, 6 months (i.e., trial completion), and 18 months (i.e., 12-month follow-up).

Discussion

Establishing the efficacy of different types and combinations of exercise training to minimize cognitive decline will advance our ability to prescribe exercise as “medicine” to treat MCI and delay the onset and progression of dementia. This trial is extremely timely as cognitive impairment and dementia pose a growing threat to global public health.

Trial registration

ClinicalTrials.gov NCT02737878. Registered on April 14, 2016.

Identification of Demographic Variables Influencing Dementia Literacy and Risk Perception Through a Global Survey

Dementia literacy is important for risk mitigation and preventative strategies before disease onset. The aim of our study was to investigate dementia literacy and how demographic characteristics influence these perceptions in order to provide evidence for how dementia-centered public health initiatives should structure their focus. We conducted a globally administered online survey, through Amazon Mechanical Turk (mTurk). Survey items evaluated: (1) personal perception on the preventability of dementia, and (2) risk awareness of lifestyle factors. Differences in risk scoring between the 598 respondents were compared using Kruskal-Wallis testing factored by demographic categorizations. Most of the sample demonstrated understanding that lifestyle factors contribute some risk toward dementia, though these risk scores were generally low. Differences in risk scoring varied by demographic characteristics. Women, older adults, those with non-post-secondary attainment, below average income, and White background tended to report lower risk scores. Public health education and initiatives for dementia prevention should focus on lifestyle risk factors, in addition to considering the barriers related to the demographic factors identified that may prevent populations from accessing programs and information.

The effect of physical exercise on functional brain network connectivity in older adults with and without cognitive impairment. A systematic review

INTRODUCTION

Neurodegeneration is a biproduct of aging that results in concomitant cognitive decline. Physical exercise is an emerging intervention to improve brain health. The underlying neural mechanisms linking exercise to neurodegeneration, however, are unclear. Functional brain network connectivity (FBNC) refers to neural regions that are anatomically separate but temporally synched in functional signalling. FBNC can be measured using functional Magnetic Resonance Imaging (fMRI) and is affected by neurodegeneration.

METHODS

We conducted a systematic review using PubMed and EMBASE to assess the effect of physical exercise on FBNC in older adults with and without cognitive impairment.

RESULTS

Our search yielded 1474 articles; after exclusion, 13 were included in the final review, 8 of which focused on cognitively healthy older adults. 10 studies demonstrated an increase in FBNC post-exercise intervention, while 11 studies showed improvements in secondary outcomes (cognitive and/or physical performance). One study showed significant correlations between FBNC and cognitive performance measures that significantly improved post-intervention.

DISCUSSION

We found evidence that physical exercise increases FBNC. When assessing the association between FBNC with physical and cognitive functioning, careful consideration must be given to variability in exercise parameters, neural regions of interest and networks examined, and heterogeneity in methodological approaches.

Brain deficits in prediabetic adults: A systematic review

Previous findings on the relationship between prediabetes (the precursor stage of type 2 diabetes) and brain health in humans are inconsistent. Thus, this systematic review of cross-sectional and longitudinal studies aimed to summarize what is currently known about brain deficits in prediabetic adults. Following the PRISMA reporting standards for systematic reviews, we conducted a comprehensive review of peer-reviewed journal articles published from 2009 to present, focusing on studies that assessed brain volume, structural connectivity, and cerebrovascular health in prediabetic adults and older adults (i.e., 18 years or older). We systematically searched PsychINFO, Scopus, Web of Science, Ovid MEDLINE, CINAHL, and EMbase databases. Quality assessment was based on the NIH Quality Assessment Tool for Observational and Cross-sectional Studies. In total, 19 studies were included in our review. Results from these studies show that prediabetes may be associated with deficits in brain structure and pathology, however, several studies also refute these findings. Moreover, we identified clear inconsistencies in study methodologies, including diabetes measures and classification, across studies that may account for these conflicting findings.

The role of physical exercise in modulating peripheral inflammatory and neurotrophic biomarkers in older adults: A systematic review and meta-analysis

BACKGROUND

Physiological cascades of neurotrophic factors and inflammatory cytokines may mediate the exercise-induced amelioration of cognition in older adults. However, there is limited understanding on how different exercise modalities improving cognition alter biomarkers. Our aim was to evaluate the effects of different exercise modalities on blood biomarker concentrations in cognitive clinical trials of older adults.

METHODS

A systematic review (SR) and meta-analysis (MA) were performed using the databases PubMed, EMBASE, and SCOPUS. After exclusions, 17 trials with 18 distinct exercise interventions were included.

RESULTS

Aerobic training increased (n = 2) or did not significantly change BDNF (n = 5), and resistance training increased (n = 2) or did not significantly change (n = 2) IGF-1. Multimodal training significantly increased (n = 1) or did not change (n = 3) BDNF. Interventions that recruited sex-specific cohorts showed an advantage in males for blood marker concentrations and cognitive performance outcomes (n = 3) compared to females (n = 3). Only one of three interventions decreased concentrations of CRP. Eight studies examining BDNF changes were suited for MA and showed that higher BDNF concentrations were reached post intervention, although not reaching statistical significance (p = .26, I² = 44 %).

DISCUSSION

Our results suggest that exercise has potential to ameliorate cognitive decline in older adults with divergent, modality-specific, neurotrophic mechanisms.

Feasibility of a 26-Week Exercise Program to Improve Brain Health in Older Adults at Risk for Type 2 Diabetes: A Pilot Study

OBJECTIVES

Older adults at risk for type 2 diabetes (i.e. overweight individuals or those with prediabetes) experience accelerated cognitive and brain deficits. Aerobic training is known to improve these deficits, but the effects of resistance training are relatively unknown. Before conducting a large-scale, randomized, controlled trial to assess the effects of resistance training, we first conducted a pilot feasibility study to examine recruitment, attendance and retention rates in this population.

METHODS

Program participants (aged 60 to 80 years, mean age 68.7±5.7 years, 50% females) at risk for type 2 diabetes (body mass index of ≥25 or fasting blood glucose of 6.1 to <7 mmol/L) underwent 26 weeks of thrice-weekly progressive resistance training (n=13) or balance-and-tone exercises (control group, n=11). Recruitment, attendance and retention rates were recorded, and study feedback from program participants and research assistants was collected via questionnaires.

RESULTS

We recruited 72 older adults (total number enrolled = 24) over 17 months. Program retention and attendance were 95.8% and 84.4%, respectively. Program participants and research assistants expressed a high level of study enjoyment, and suggestions on how to improve study procedures were provided.

CONCLUSIONS

Based on our findings, a large-scale study in this at-risk group of older adults is feasible, and key strategies to improving future trials were identified.

Memory Function and Brain Functional Connectivity Adaptations Following Multiple-Modality Exercise and Mind-Motor Training in Older Adults at Risk of Dementia: An Exploratory Sub-Study

Background

Multiple-modality exercise improves brain function. However, whether task-based brain functional connectivity (FC) following exercise suggests adaptations in preferential brain regions is unclear. The objective of this study was to explore memory function and task-related FC changes following multiple-modality exercise and mind-motor training in older adults with subjective cognitive complaints.

Methods

We performed secondary analysis of memory function data in older adults [n = 127, mean age 67.5 (7.3) years, 71% women] randomized to an exercise intervention comprised of 45 min of multiple-modality exercise with additional 15 min of mind-motor training (M4 group, n = 63) or an active control group (M2 group, n = 64). In total, both groups exercised for 60 min/day, 3 days/week, for 24 weeks. We then conducted exploratory analyses of functional magnetic resonance imaging (fMRI) data collected from a sample of participants from the M4 group [n = 9, mean age 67.8 (8.8) years, 8 women] who completed baseline and follow-up task-based fMRI assessment. Four computer-based memory tasks from the Cambridge Brain Sciences cognitive battery (i.e. Monkey Ladder, Spatial Span, Digit Span, Paired Associates) were employed, and participants underwent 5 min of continuous fMRI data collection while completing the tasks. Behavioral data were analyzed using linear mixed models for repeated measures and paired-samples t-test. All fMRI data were analyzed using group-level independent component analysis and dual regression procedures, correcting for voxel-wise comparisons.

Results

Our findings indicated that the M4 group showed greater improvements in the Paired Associates tasks compared to the M2 group at 24 weeks [mean difference: 0.47, 95% confidence interval (CI): 0.08 to 0.86, p = 0.019]. For our fMRI analysis, dual regression revealed significant decrease in FC co-activation in the right precentral/postcentral gyri after the exercise program during the Spatial Span task (corrected p = 0.008), although there was no change in the behavioral task performance. Only trends for changes in FC were found for the other tasks (all corrected p < 0.09). In addition, for the Paired Associates task, there was a trend for increased co-activation in the right temporal lobe (Brodmann Area = 38, corrected p = 0.07), and left middle frontal temporal gyrus (corrected p = 0.06). Post hoc analysis exploring voxel FC within each group spatial map confirmed FC activation trends observed from dual regression.

Conclusion

Our findings suggest that multiple modality exercise with mind-motor training resulted in greater improvements in memory compared to an active control group. There were divergent FC adaptations including significant decreased co-activation in the precentral/postcentral gyri during the Spatial Span task. Borderline significant changes during the Paired Associates tasks in FC provided insight into the potential of our intervention to promote improvements in visuospatial memory and impart FC adaptations in brain regions relevant to Alzheimer's disease risk.

Clinical Trial Registration

The trial was registered in ClinicalTrials.gov in April 2014, Identifier: NCT02136368.

Feasibility of a 6-month pilot randomised controlled trial of resistance training on cognition and brain health in Canadian older adults at-risk for diabetes: study protocol

INTRODUCTION

Type 2 diabetes (T2D) is associated with cognitive deficits and increased risk of dementia, and thus individuals at high risk for T2D (ie, those who are overweight or prediabetic) are also at greater risk for cognitive decline. Aerobic exercise is known to preserve and improve cognitive function, but the effects of resistance training (RT) are much less known in older adults. Moreover, research on the effects of RT on cognition and brain health (structure and function) in older adults at-risk for diabetes is limited. To address this question, a 6-month RT intervention is needed. Importantly, before conducting a full-scale randomised controlled trial (RCT), we are conducting a feasibility pilot study to assess potential recruitment rates, adherence and retention in this specific population.

METHODS AND ANALYSIS

We are conducting a 6-month, thrice-weekly RT RCT. Participants (aged 60-80; sedentary; fasting plasma glucose of 6.1-7.0 mmol/L or body mass index ≥25) are randomised into one of two groups: (1) RT or (2) balance and tone (control). Based on other exercise trials using a similar population, we will consider our trial feasible if we have adherence and retention at 70%. Recruitment rate will be measured as time it takes to enrol 20 participants. To assess behavioural and MRI data, we will report descriptive statistics and estimation using a 95% CI.

ETHICS AND DISSEMINATION

Our study has received ethics approval from the Health Sciences Research Ethics Board at Western University. As this is a small pilot study, data will only be made available to other researchers on request. Results from this study will be disseminated via academic publication.

TRIAL REGISTRATION NUMBER

NCT03254381.

Can meditation improve attention in older adults? Study protocol for a 4-week proof-of-concept intervention

Background

Falls are a major health care concern for our aging population. Previous research has identified impaired sustained attention as a risk factor for falls. Recently, meditation has been shown to improve different types of attention in various populations. However, there are no studies to date examining whether meditation training can improve sustained attention and mobility in older adults.

Methods

We are conducting a 4-week proof-of-concept meditation intervention. We will recruit community-dwelling older adults. Participants will be randomized into one of two groups: (1) meditation training or (2) music listening (control). All participants will complete three 20-min group sessions per week and will be encouraged to continue their practice independently on the remaining days each week. Our primary outcome measure is behavioral performance on the Sustained Attention to Response Task (SART). Our secondary and tertiary outcomes include electroencephalograms (EEG) to assess attention and cognitive processing, mobility, and executive function.

Discussion

Our proof-of-concept intervention aims to examine whether meditation training can improve sustained attention in older adults, who are known to be susceptible to falls. Importantly, our research has the potential to inform future clinical trials aimed at improving mobility and reducing falls risk in our aging population.

Trial registration

Clinicaltrials.gov ID NCT03417635.

The effects of physical exercise on executive function in community-dwelling older adults living with Alzheimer's-type dementia: A systematic review

Executive function deficit is an indicator of Alzheimer's-type dementia and manifests as disruptions of attentional control, memory, cognitive flexibility, planning, and reasoning, among other cognitive problems. Physical exercise is suggested to have a protective effect on global cognition with aging. However, whether it influences executive function in people living with Alzheimer's-type dementia specifically is unknown. The current systematic review examined the efficacy of physical exercise on executive function performance in community-dwelling older adults living with Alzheimer's-type dementia. An electronic search of databases retrieved randomized and non-randomized controlled trials of community-dwelling older adults diagnosed with Alzheimer's-type dementia who completed a physical exercise intervention and who were assessed using an executive function outcome measure. Methodological quality of six studies meeting the inclusion criteria published between 2009 and 2016 was scored independently by two raters using the Physiotherapy Evidence Database and a Cochrane informed domain-based assessment of risk of bias. Trends toward improvement in executive function scores were seen across all six studies, and significant improvement was seen in four of the eligible studies. Future studies should explore the benefits of the American College of Sports Medicine recommended 150 min of physical exercise per week with select measures of executive function.

Aerobic exercise promotes executive functions and impacts functional neural activity among older adults with vascular cognitive impairment

BACKGROUND

Vascular cognitive impairment (VCI) results from cerebrovascular disease, and worldwide, it is the second most common type of cognitive dysfunction. While targeted aerobic training is a promising approach to delay the progression of VCI by reducing cardiometabolic risk factors, few randomised controlled trials to date have specifically assessed the efficacy of aerobic training on cognitive and brain outcomes in this group at risk for functional decline.

AIM

To examine the effect of moderate-intensity aerobic training on executive functions and functional neural activity among older adults with mild subcortical ischaemic VCI (SIVCI).

METHODS

Older adults with mild SIVCI were randomly assigned to: (1) 6-month, 3×/week aerobic training (n=10) or (2) usual care (control; n=11). Participants completed functional MRI (fMRI) at baseline and trial completion. During the fMRI sessions, behavioural performance on the Eriksen flanker task and task-evoked neural activity were assessed.

RESULTS

At trial completion, after adjusting for baseline general cognition, total white matter lesion volume and flanker performance, compared with the control group, the aerobic training group significantly improved flanker task reaction time. Moreover, compared with the controls, the aerobic training group demonstrated reduced activation in the left lateral occipital cortex and right superior temporal gyrus. Reduced activity in these brain regions was significantly associated with improved (ie, faster) flanker task performance at trial completion.

SUMMARY

Aerobic training among older adults with mild SIVCI can improve executive functions and neural efficiency of associated brain areas. Future studies with greater sample size should be completed to replicate and extend these findings.

White Matter Volume Mediates the Relationship Between Self-Efficacy and Mobility in Older Women

Background/Study Context: With our aging population, understanding determinants of healthy aging is a priority. One essential component of healthy aging is mobility. Although self-efficacy can directly impact mobility in older adults, it is unknown what role brain health may play in this relationship.

METHODS

The authors 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.

RESULTS

The authors 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 = .28), which, in turn, was associated with better mobility (r = -.30).

CONCLUSION

This 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.

Exercise Mode Moderates the Relationship Between Mobility and Basal Ganglia Volume in Healthy Older Adults

OBJECTIVES

To examine whether 12 months of aerobic training (AT) moderated the relationship between change in mobility and change in basal ganglia volume than balance and toning (BAT) exercises in older adults.

DESIGN

Secondary analysis of a randomized controlled trial.

SETTING

Champaign-Urbana, Illinois.

PARTICIPANTS

Community-dwelling older adults (N=101; mean age 66.4).

INTERVENTION

Twelve-month exercise trial with two groups: AT and BAT.

MEASUREMENTS

Mobility was assessed using the Timed Up and Go test. Basal ganglia (putamen, caudate nucleus, pallidum) was segmented from T1-weighted magnetic resonance images using the Oxford Centre for Functional Magnetic Resonance Imaging of the Brain Software Library Integrated Registration and Segmentation Tool. Measurements were obtained at baseline and trial completion. Hierarchical multiple regression was conducted to examine whether exercise mode moderates the relationship between change in mobility and change in basal ganglia volume over 12 months. Age, sex, and education were included as covariates.

RESULTS

Exercise significantly moderated the relationship between change in mobility and change in left putamen volume. Specifically, for the AT group, volume of the left putamen did not change, regardless of change in mobility. Similarly, in the BAT group, those who improved their mobility most over 12 months had no change in left putamen volume, although left putamen volume of those who declined in mobility levels decreased significantly.

CONCLUSION

The primary finding that older adults who engaged in 12 months of BAT training and improved mobility exhibited maintenance of brain volume in an important region responsible for motor control provides compelling evidence that such exercises can contribute to the promotion of functional independence and healthy aging.

Structural neural correlates of impaired mobility and subsequent decline in executive functions: a 12-month prospective study

Impaired mobility, such as falls, may be an early biomarker of subsequent cognitive decline and is associated with subclinical alterations in both brain structure and function. In this 12-month prospective study, we examined whether there are volumetric differences in gray matter and subcortical regions, as well as cerebral white matter, between older fallers and non-fallers. In addition, we assessed whether these baseline volumetric differences are associated with changes in cognitive function over 12months. A total of 66 community-dwelling older adults were recruited and categorized by their falls status. Magnetic resonance imaging occurred at baseline and participants' physical and cognitive performances were assessed at baseline and 12-months. At baseline, fallers showed significantly lower volumes in gray matter, subcortical regions, and cerebral white matter compared with non-fallers. Notably, fallers had significantly lower left lateral orbitofrontal white matter volume. Moreover, lower left lateral orbitofrontal white matter volume at baseline was associated with greater decline in set-shifting performance over 12months. Our data suggest that falls may indicate subclinical alterations in regional brain volume that are associated with subsequent decline in executive functions.

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.

Basics of neuroanatomy and neurophysiology

This chapter presents an overview of the anatomy and functioning of the central nervous system. We begin the discussion by first examining the cellular basis of neural transmission. Then we present a brief description of the brain's white and gray matter and associated diseases, including a discussion of white-matter lesions. Finally, we place this information into context by discussing how the central nervous system integrates complex information to guide key functional systems, including the visual, auditory, chemosensory, somatic, limbic, motor, and autonomic systems. Where appropriate, we have supplied information pertaining to pathologic and functional outcomes of damage to the central nervous system. Also included is a brief description of important tools and methods used in the study of neuroanatomy and neurophysiology. Overall, this chapter provides a basic review of the concepts required to understand and interpret the clinical disorders and related material presented in the subsequent chapters of this book.

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.

Aerobic exercise increases hippocampal volume in older women with probable mild cognitive impairment: a 6-month randomised controlled trial

BACKGROUND

Mild cognitive impairment (MCI) is a well-recognised risk factor for dementia and represents a vital opportunity for intervening. Exercise is a promising strategy for combating cognitive decline by improving 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 resistance training (RT) and AT improved memory. In this secondary analysis, we investigated: (1) the effect of RT and AT on hippocampal volume and (2) the association between change in hippocampal volume and change in memory.

METHODS

86 women aged 70-80 years with probable MCI were randomly assigned to a 6-month, twice-weekly programme of: (1) AT, (2) RT or (3) balance and tone training (BAT; ie, control). At baseline and trial completion, participants performed a 3T MRI scan to determine hippocampal volume. Verbal memory and learning were assessed by Rey's Auditory Verbal Learning Test.

RESULTS

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).

CONCLUSIONS

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.

TRAIL REGISTRATION NUMBER

NCT00958867.

Disruptions in brain networks of older fallers are associated with subsequent cognitive decline: a 12-month prospective exploratory study

Cognitive impairment and impaired mobility are major public health concerns. There is growing recognition that impaired mobility is an early biomarker of cognitive impairment and dementia. The neural basis for this association is currently unclear. We propose disrupted functional connectivity as a potential mechanism. In this 12-month prospective exploratory study, we compared functional connectivity of four brain networks– the default mode network (DMN), fronto-executive network (FEN), fronto-parietal network (FPN), and the primary motor sensory network (SMN) – between community-dwelling older adults with ≥ two falls in the last 12 months and their non-falling counterparts (≤ one fall in the last 12 months). Functional connectivity was examined both at rest and during a simple motor tapping task. Compared with non-fallers, fallers showed more connectivity between the DMN and FPN during right finger tapping (p = 0.04), and significantly less functional connectivity between the SMN and FPN during rest (p≤0.05). Less connectivity between the SMN and FPN during rest was significantly associated with greater decline in both cognitive function and mobility over the12-month period (r = −0.32 and 0.33 respectively; p≤0.04). Thus, a recent history of multiple falls among older adults without a diagnosis of dementia may indicate sub-clinical changes in brain function and increased risk for subsequent decline.

Mind-wandering and falls risk in older adults

Although 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. In addition, 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.

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.

Change in body fat mass is independently associated with executive functions in older women: a secondary analysis of a 12-month randomized controlled trial

OBJECTIVES

To investigate the independent contribution of change in sub-total body fat and lean mass to cognitive performance, specifically the executive processes of selective attention and conflict resolution, in community-dwelling older women.

METHODS

This secondary analysis included 114 women aged 65 to 75 years old. Participants were randomly allocated to once-weekly resistance training, twice-weekly resistance training, or twice-weekly balance and tone training. The primary outcome measure was the executive processes of selective attention and conflict resolution as assessed by the Stroop Test. Sub-total body fat and lean mass were measured by dual-energy x-ray absorptiometry (DXA) to determine the independent association of change in both sub-total body fat and sub-total body lean mass with Stroop Test performance at trial completion.

RESULTS

A multiple linear regression model showed reductions in sub-total body fat mass to be independently associated with better performance on the Stroop Test at trial completion after accounting for baseline Stroop performance, age, baseline global cognitive state, baseline number of comorbidities, baseline depression, and experimental group. The total variance explained was 39.5%; change in sub-total body fat mass explained 3.9% of the variance. Change in sub-total body lean mass was not independently associated with Stroop Test performance (P>0.05).

CONCLUSION

Our findings suggest that reductions in sub-total body fat mass - not sub-total lean mass - is associated with better performance of selective attention and conflict resolution.

Examining the relationship between specific cognitive processes and falls risk in older adults: a systematic review

This systematic review aims to establish which cognitive domains are associated with falls or falls risk. 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 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.

Self-efficacy is independently associated with brain volume in older women

BACKGROUND

ageing 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.

METHOD

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 65-75 years old. Falls-related self-efficacy was assessed by the activities-specific balance confidence (ABC) scale.

RESULTS

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%.

CONCLUSION

we provide novel evidence that falls-related self-efficacy, a modifiable risk factor for healthy ageing, is positively associated with total brain volume and total grey matter volume.

TRIAL REGISTRATION

ClinicalTrials.gov Identifier: NCT00426881.

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 randomised controlled trials suggest that exercise reduce falls via mechanisms other than improved physiological function. The authors propose that improved cognitive function - specifically, executive functions - and associated functional plasticity may be an important yet underappreciated mechanism by which the exercise reduces falls in older adults.

Increased cognitive load leads to impaired mobility decisions in seniors at risk for falls

Successful mobility requires appropriate decision-making. Seniors with reduced executive functioning-such as senior fallers-may be prone to poor mobility judgments, especially under dual-task conditions. We classified participants as "At-Risk" and "Not-At-Risk" for falls using a validated physiological falls-risk assessment. Dual-task performance was assessed in a virtual reality environment where participants crossed a simulated street by walking on a manual treadmill while listening to music or conversing on a phone. Those "At-Risk" experienced more collisions with oncoming cars and had longer crossing times in the Phone condition compared to controls. We conclude that poor mobility judgments during a dual-task leads to unsafe mobility for those at-risk for falls.

Functional neural correlates of reduced physiological falls risk

Background

It is currently unclear whether the function of brain regions associated with executive cognitive processing are independently associated with reduced physiological falls risk. If these are related, it would suggest that the development of interventions targeted at improving executive neurocognitive function would be an effective new approach for reducing physiological falls risk in seniors.

Methods

We performed a secondary analysis of 73 community-dwelling senior women aged 65 to 75 years old who participated in a 12-month randomized controlled trial of resistance training. Functional MRI data were acquired while participants performed a modified Eriksen Flanker Task - a task of selective attention and conflict resolution. Brain volumes were obtained using MRI. Falls risk was assessed using the Physiological Profile Assessment (PPA).

Results

After accounting for baseline age, experimental group, baseline PPA score, and total baseline white matter brain volume, baseline activation in the left frontal orbital cortex extending towards the insula was negatively associated with reduced physiological falls risk over the 12-month period. In contrast, baseline activation in the paracingulate gyrus extending towards the anterior cingulate gyrus was positively associated with reduced physiological falls risk.

Conclusions

Baseline activation levels of brain regions underlying response inhibition and selective attention were independently associated with reduced physiological falls risk. This suggests that falls prevention strategies may be facilitated by incorporating intervention components - such as aerobic exercise - that are specifically designed to induce neurocognitive plasticity.

Trial Registration

ClinicalTrials.gov Identifier: NCT00426881

Exercise, brain, and cognition across the life span

This is a brief review of current evidence for the relationships between physical activity and exercise and the brain and cognition throughout the life span in non-pathological populations. We focus on the effects of both aerobic and resistance training and provide a brief overview of potential neurobiological mechanisms derived from non-human animal models. Whereas research has focused primarily on the benefits of aerobic exercise in youth and young adult populations, there is growing evidence that both aerobic and resistance training are important for maintaining cognitive and brain health in old age. Finally, in these contexts, we point out gaps in the literature and future directions that will help advance the field of exercise neuroscience, including more studies that explicitly examine the effect of exercise type and intensity on cognition, the brain, and clinically significant outcomes. There is also a need for human neuroimaging studies to adopt a more unified multi-modal framework and for greater interaction between human and animal models of exercise effects on brain and cognition across the life span.

Age-related changes in the attentional control of visual cortex: a selective problem in the left visual hemifield

To what extent does our visual-spatial attention change with age? In this regard, it has been previously reported that relative to young controls, seniors show delays in attention-related sensory facilitation. Given this finding, our study was designed to examine two key questions regarding age-related changes in the effect of spatial attention on sensory-evoked responses in visual cortex--are there visual field differences in the age-related impairments in sensory processing, and do these impairments co-occur with changes in the executive control signals associated with visual spatial orienting? Therefore, our study examined both attentional control and attentional facilitation in seniors (aged 66-74 years) and young adults (aged 18-25 years) using a canonical spatial orienting task. Participants responded to attended and unattended peripheral targets while we recorded event-related potentials (ERPs) to both targets and attention-directing spatial cues. We found that not only were sensory-evoked responses delayed in seniors specifically for unattended events in the left visual field as measured via latency shifts in the lateral occipital P1 elicited by visual targets, but seniors also showed amplitude reductions in the anterior directing attentional negativity (ADAN) component elicited by cues directing attention to the left visual field. At the same time, seniors also had significantly higher error rates for targets presented in the left vs. right visual field. Taken together, our data thus converge on the conclusion that age-related changes in visual spatial attention involve both sensory-level and executive attentional control processes, and that these effects appear to be strongly associated with the left visual field.

Resistance training and executive functions: a 12-month randomized controlled trial

BACKGROUND

Cognitive decline among seniors is a pressing health care issue. Specific exercise training may combat cognitive decline. We compared the effect of once-weekly and twice-weekly resistance training with that of twice-weekly balance and tone exercise training on the performance of executive cognitive functions in senior women.

METHODS

In this single-blinded randomized trial, 155 community-dwelling women aged 65 to 75 years living in Vancouver were randomly allocated to once-weekly (n = 54) or twice-weekly (n = 52) resistance training or twice-weekly balance and tone training (control group) (n = 49). The primary outcome measure was performance on the Stroop test, an executive cognitive test of selective attention and conflict resolution. Secondary outcomes of executive cognitive functions included set shifting as measured by the Trail Making Tests (parts A and B) and working memory as assessed by verbal digit span forward and backward tests. Gait speed, muscular function, and whole-brain volume were also secondary outcome measures.

RESULTS

Both resistance training groups significantly improved their performance on the Stroop test compared with those in the balance and tone group (P < or = .03). Task performance improved by 12.6% and 10.9% in the once-weekly and twice-weekly resistance training groups, respectively; it deteriorated by 0.5% in the balance and tone group. Enhanced selective attention and conflict resolution was significantly associated with increased gait speed. Both resistance training groups demonstrated reductions in whole-brain volume compared with the balance and tone group at the end of the study (P < or = .03).

CONCLUSION

Twelve months of once-weekly or twice-weekly resistance training benefited the executive cognitive function of selective attention and conflict resolution among senior women.

TRIAL REGISTRATION

clinicaltrials.gov Identifier: NCT00426881.

Are impairments in visual-spatial attention a critical factor for increased falls risk in seniors? An event-related potential study

Falls are experienced annually by approximately one third of community dwellers over the age of 65, and while neuro-cognitive deficits have been shown to increase falls risk, the specific nature of these deficits remain unspecified. Here we examined whether visual-spatial attention may be a core neuro-cognitive system showing abnormal function in fallers. Using a between-groups design, we recorded event-related potentials in a canonical spatial cuing task performed by two groups of senior (aged 65+ years old) participants: those with a recent history of falls and those with no such history. In terms of attentional control systems in cortex, we found no significant differences in function between groups. However, in terms of attentional facilitation of cortical processing, we found that fallers manifest specific abnormalities in the sensory/perceptual processing of targets in the left visual field. Our findings thus suggest that fallers have specific deficits in visuocortical systems associated with attentional enhancement of events on the left side of visual space.

Dual-task gait performance among community-dwelling senior women: the role of balance confidence and executive functions

BACKGROUND

Exploring factors that contribute to dual-task gait performance among seniors is of particular interest in falls prevention because dual-task-related gait changes are associated with increased falls risk. It is unclear currently which specific executive processes are most relevant to dual-task gait performance and whether "balance confidence" is independently associated with dual-task gait performance.

METHODS

A cross-sectional analysis of 140 senior women aged 65-75 years old. Balance confidence was assessed by the Activities-Specific Balance Confidence scale. Three key executive processes were assessed by standard neuropsychological tests: (i) set shifting, (ii) working memory, and (iii) response inhibition. Dual-task gait performance was assessed by the simple and complex versions of the walking while talking (WWT) test. Two linear regression models were constructed to determine the independent association of executive functions and balance confidence with: (i) simple WWT completion time and (ii) complex WWT completion time.

RESULTS

Balance confidence was independently associated with both simple and complex WWT completion times after accounting for age, time to walk 40 ft without talking, and global cognition. Set shifting was independently associated with complex WWT completion time; no executive processes were independently associated with simple WWT completion time.

CONCLUSIONS

This study highlights that balance confidence is independently associated with dual-task gait performance. Furthermore, executive functions do not play a significant role in dual-task gait performance when the concurrent cognitive load is low. Clinicians may need to consider balance confidence and executive functions in the assessment and rehabilitation of dual-task gait performance among community-dwelling seniors.