Functional connectivity underpinning changes in life-space mobility in older adults with mild cognitive impairment: A 12-month prospective study

Association of physical function with connectivity in the sensorimotor and dorsal attention networks: why examining specific components of physical function matters

Declining physical function with aging is associated with structural and functional brain network organization. Gaining a greater understanding of network associations may be useful for targeting interventions that are designed to slow or prevent such decline. Our previous work demonstrated that the Short Physical Performance Battery (eSPPB) score and body mass index (BMI) exhibited a statistical interaction in their associations with connectivity in the sensorimotor cortex (SMN) and the dorsal attention network (DAN). The current study examined if components of the eSPPB have unique associations with these brain networks. Functional magnetic resonance imaging was performed on 192 participants in the BNET study, a longitudinal and observational trial of community-dwelling adults aged 70 or older. Functional brain networks were generated for resting state and during a motor imagery task. Regression analyses were performed between eSPPB component scores (gait speed, complex gait speed, static balance, and lower extremity strength) and BMI with SMN and DAN connectivity. Gait speed, complex gait speed, and lower extremity strength significantly interacted with BMI in their association with SMN at rest. Gait speed and complex gait speed were interacted with BMI in the DAN at rest while complex gait speed, static balance, and lower extremity strength interacted with BMI in the DAN during motor imagery. Results demonstrate that different components of physical function, such as balance or gait speed and BMI, are associated with unique aspects of brain network organization. Gaining a greater mechanistic understanding of the associations between low physical function, body mass, and brain physiology may lead to the development of treatments that not only target specific physical function limitations but also specific brain networks.

The level of life space mobility among community-dwelling elderly: A systematic review and meta-analysis

BACKGROUND

Multiple countries have conducted surveys on the level of life space mobility for community-dwelling elderly through the Life-Space Assessment, the results vary greatly, from 41.7 to 88.6. However, there is no meta-analysis on the current situation of community-dwelling elderly life space mobility.

OBJECTIVE

To systematically assess the global level of life space mobility for community-dwelling elderly, to identify potential covariates such as geographical regions, survey years, gender, and age that contribute to the heterogeneity between the studies, and to identify the dynamic trend based on survey years.

DESIGN

Systematic review and meta-analysis.

DATA SOURCES

Two reviewers searched the following 8 electronic bibliographic databases from inception until May 28, 2023: PubMed, The Cochrane Library, Web of Science, Embase, Chinese Biomedical Database, China Knowledge Resource Integrated Database, WanFang, and Weipu Database.

REVIEW METHODS

This review was conducted using the Stata 14.1 and R 4.3.1. The Cochrane's Q statistical and I2 index were used to test for heterogenicity and assess the degree of heterogenicity, respectively. Studies were appraised using the Agency for Healthcare Research and Quality tool, the Newcastle-Ottawa Scale for the quality of cross-sectional studies, cohort studies, respectively.

RESULTS

A total of 29 studies were selected from databases and reference lists. The pooled score of Life-Space Assessment was 66.84 (95% CI: 63.30-70.39) and the prevalence of restricted life space was 42% (95% CI: 0.27-0.57). The geographical regions, survey years, gender were found to be a significant covariate of the pooled score of life space mobility estimate in the subgroup analysis. The mean score of Life-Space Assessment gradually achieved stability after 2017.

CONCLUSIONS

The life space mobility of community-dwelling elderly in the global is at a moderate level, with 42% of them experiencing restricted life space. South America, females and earlier survey years have a lower level of life space mobility. In the future, the government should identify vulnerable groups for targeted intervention to promote the level of LSM in the community-dwelling elderly.

REGISTRATION

PROSPERO [CRD42023443054].

Associations of physical function and body mass index with functional brain networks in community-dwelling older adults

Deficits in physical function that occur with aging contribute to declines in quality of life and increased mortality. There has been a growing interest in examining associations between physical function and neurobiology. Whereas high levels of white matter disease have been found in individuals with mobility impairments in structural brain studies, much less is known about the relationship between physical function and functional brain networks. Even less is known about the association between modifiable risk factors such as body mass index (BMI) and functional brain networks. The current study examined baseline functional brain networks in 192 individuals from the Brain Networks and mobility (B-NET) study, an ongoing longitudinal, observational study in community-dwelling adults aged 70 and older. Physical function and BMI were found to be associated with sensorimotor and dorsal attention network connectivity. There was a synergistic interaction such that high physical function and low BMI were associated with the highest network integrity. White matter disease did not modify these relationships. Future work is needed to understand the causal direction of these relationships.

Myelin and Physical Activity in Older Adults With Cerebral Small Vessel Disease and Mild Cognitive Impairment

BACKGROUND

Myelin loss is a feature of cerebral small vessel disease (cSVD). Although physical activity levels may exert protective effects over cSVD pathology, its specific relationship with myelin content in people living with the cSVD is unknown. Thus, we investigated whether physical activity levels are associated with myelin in community-dwelling older adults with cSVD and mild cognitive impairment.

METHODS

Cross-sectional data from 102 individuals with cSVD and mild cognitive impairment were analyzed (mean age [SD] = 74.7 years [5.5], 63.7% female). Myelin was measured using a magnetic resonance gradient and spin echo sequence. Physical activity was estimated using the Physical Activity Scale for the Elderly. Hierarchical regression models adjusting for total intracranial volume, age, sex, body mass index, and education were conducted to determine the associations between myelin content and physical activity. Significant models were further adjusted for white matter hyperintensity volume.

RESULTS

In adjusted models, greater physical activity was linked to higher myelin content in the whole-brain white matter (R2change = .04, p = .048). Greater physical activity was also associated with myelin content in the sagittal stratum (R2change = .08, p = .004), anterior corona radiata (R2change = .04, p = .049), and genu of the corpus callosum (R2change = .05, p = .018). Adjusting for white matter hyperintensity volume did not change any of these associations.

CONCLUSIONS

Physical activity may be a strategy to maintain myelin in older adults with cSVD and mild cognitive impairment. Future randomized controlled trials of exercise are needed to determine whether exercise increases myelin content.

Effects of aging on cognitive and brain inter-network integration patterns underlying usual and dual-task gait performance

Introduction

Aging affects the interplay between cognition and gait performance. Neuroimaging studies reported associations between gait performance and structural measures; however, functional connectivity (FC) analysis of imaging data can help to identify dynamic neural mechanisms underlying optimal performance. Here, we investigated the effects on divergent cognitive and inter-network FC patterns underlying gait performance during usual (UW) and dual-task (DT) walking.

Methods

A total of 115 community-dwelling, healthy participants between 20 and 80 years were enrolled. All participants underwent comprehensive cognitive and gait assessments in two conditions and resting state functional MRI (fMRI) scans. Inter-network FC from motor-related to 6 primary cognitive networks were estimated. Step-wise regression models tested the relationships between gait parameters, inter-network FC, neuropsychological scores, and demographic variables. A threshold of p < 0.05 was adopted for all statistical analyses.

Results

UW was largely associated with FC levels between motor and sustained attention networks. DT performance was associated with inter-network FC between motor and divided attention, and processing speed in the overall group. In young adults, UW was associated with inter-network FC between motor and sustained attention networks. On the other hand, DT performance was associated with cognitive performance, as well as inter-network connectivity between motor and divided attention networks (VAN and SAL). In contrast, the older age group (> 65 years) showed increased integration between motor, dorsal, and ventral attention, as well as default-mode networks, which was negatively associated with UW gait performance. Inverse associations between motor and sustained attention inter-network connectivity and DT performance were observed.

Conclusion

While UW relies on inter-network FC between motor and sustained attention networks, DT performance relies on additional cognitive capacities, increased motor, and executive control network integration. FC analyses demonstrate that the decline in cognitive performance with aging leads to the reliance on additional neural resources to maintain routine walking tasks.

Assessing timewise changes over 15 months in life-space mobility among community-dwelling elderly persons

Background

The purpose of this study was to examine the differences of timewise changes in life-space mobility between elderly people living alone and those living with others among community-dwelling elderly people from a day care facility with a rehabilitation service for seniors.

Methods

The present study used a longitudinal design with repeated measures every 3 months. In conformity with our inclusion criteria, this study included 233 community-dwelling elderly users of a day care facility with rehabilitation services for seniors in Japan. We analyzed the life-space assessment (LSA) scores collected at five time points (baseline, 3 months, 6 months, 9 months, and 12 months) using mixed-effects models with random intercepts and slopes over time. In the present study, the explanatory variables of interest were time, and living situation (living alone or with others). As possible confounders, we considered the following: (a) age, (b) sex, (c) social frailty, (d) physical frailty, (e) mild cognitive impairment (MCI), (f) depression, and (g) economic satisfaction.

Results

The mean age of participants was 78.9 years (SD = 7.7), their mean LSA score was 60.1 points (SD = 25.7), and 42.9% of the participants were men. After adjusting for age, gender, frailty, depression, MCI, and economic satisfaction, the mean LSA score of older adults who lived with others was significantly lower (7.42 points, 95%CI = − 18.30 to − 0.15, p = 0.048) than that older adults who lived alone.

Discussion

Community-dwelling older adults who used a day care center with rehabilitation services and lived with others had a smaller life-space at baseline than those who lived alone. This suggests that there is a need to pay more attention to social frailty among both older adults who live alone and those who live with others.

Conclusions

According to a multilevel analysis growth model, elderly persons who lived with others had significantly lower life-space mobility than those who lived alone.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12877-020-01882-4.

Life-Space Mobility in the Elderly: Current Perspectives

Life-space mobility (LSM) is a concept for assessing patterns of functional mobility over time. LSM is gaining traction in the research of geriatric population health. Several instruments have been developed to measure LSM, such as the University of Alabama at Birmingham Life-Space Assessment (LSA) or the Nursing Home Life-Space Diameter instrument. There has been exponential growth in the use of instruments measuring LSM in studies of older adults since the concept was introduced in 1985. In response to the increased volume of publications with clinical applicability to those working in geriatric health or conducting population-based research in older adults, we conducted a narrative review: a) to provide a summary of the articles that have assessed validation of the University of Alabama at Birmingham LSA instrument, the most widely used instrument to assess LSM in older adults; and b) to provide a summary of the research articles that have examined LSM as independent or outcome variable. Studies for this review were obtained with an organized search format and were included if they were published in the past 20 years, written in English, published in peer-reviewed literature, and included LSM as an independent or outcome variable. Seventy-nine articles were identified: 36 that employed a cross-sectional design and 22 that employed a longitudinal/prospective design to examine LSM as outcome variable; 17 longitudinal/prospective design articles that examined LSM as primary independent variable; 3 review articles; and 1 systematic review. Areas of research included physical function, cognitive function, sensory impairment, mental health, falls, frailty, comorbidities, healthcare use, mortality, and social/environmental factors. These studies showed that LSM instruments can accurately predict morbidity, mortality, and healthcare use.

Gait speed, life-space mobility and mild cognitive impairment in patients with coronary artery disease

Slow gait speed and restricted life-space mobility predict cognitive decline and dementia in healthy older adults, yet the relation between gait speed or life-space mobility and cognitive function remains poorly understood in patients with coronary artery disease (CAD). We, therefore, examined the following relations: that between gait speed and cognitive function, and mild cognitive impairment (MCI) and that between life-space mobility and cognitive function, and MCI. We conducted a cross-sectional study of 240 non-dementia patients who met the study criteria from 2132 consecutive CAD patients. MCI was estimated with the Japanese version of the Montreal Cognitive Assessment (MoCA-J). Gait speed was measured to perform gait trials at the patients' usual walking pace, and life-space mobility was evaluated using the Life-Space Assessment (LSA). We investigated the relation between gait speed or life-space mobility and cognitive function by Pearson correlation analysis, whereas multivariable logistic regression analysis was conducted for detecting MCI. Gait speed and LSA scores were positively associated with the MoCA-J score (r = 0.54, p < 0.001 and r = 0.44, p < 0.001, respectively), and both were independently associated with MCI in the multivariable logistic regression analysis (odds ratio 0.007, p < 0.001, and odds ratio 0.98, p = 0.038, respectively). Cognitive impairment can be easily detected by assessment of gait speed and life-space mobility. Interventions to improve gait speed and life-space mobility may lead to the improvement of cognitive function and MCI in patients with CAD.

Differential Effects of Tai Chi Chuan (Motor-Cognitive Training) and Walking on Brain Networks: A Resting-State fMRI Study in Chinese Women Aged 60

Background: This cross-sectional study aimed to investigate whether a long-term engagement in different types of physical exercise may influence resting-state brain networks differentially. In particular, we studied if there were differences in resting-state functional connectivity measures when comparing older women who are long-term practitioners of tai chi chuan or walking. Method: We recruited 20 older women who regularly practiced tai chi chuan (TCC group), and 22 older women who walked regularly (walking group). Both the TCC group and the walking group underwent a resting-state functional magnetic resonance imaging (rs-fMRI) scan. The acquired rs-fMRI data of all participants were analyzed using independent component analysis. Age and years of education were added as co-variables. Results: There were significant differences in default network, sensory-motor network, and visual network of rs-fMRI between the TCC group and walking group (p < 0.05). Conclusions: The findings of the current study suggested that long-term practice of different types of physical exercises (TCC vs. walking) influenced brain functional networks and brain functional plasticity of elderly women differentially. Our findings encourage further research to investigate whether those differences in resting-state functional connectivity as a function of the type of physical exercise have implications for the prevention of neurological diseases.