Sedentary behavior as a risk factor for cognitive decline? A focus on the influence of glycemic control in brain health

Breaking up sitting enhances neurocognitive function which is associated with improved postprandial glucose regulation in healthy adults: A randomized crossover study

BACKGROUND AND AIMS

The glucose-centric hypothesis postulates that glycemic control may influence cognition. While research has examined the effects of breaking up sitting on blood glucose and inhibitory control, few studies have integrated these data and employed event-related potential (ERP) measures to delve into the neuroelectric processes. This study aimed to investigate the effects of breaking up sitting on postprandial blood glucose response, inhibitory control, and P3 component.

METHODS

Eighteen healthy male participants [25 ± 4 years, 23.5 ± 3.2 kg/m² (mean ± SD)] were subjected to 3.5 h uninterrupted sitting (SIT) or with 3 min walking at 6.4 km/h every 30 min (ACTIVE) trials in a randomized crossover design. The Stroop task was administered to assess inhibitory control before and after SIT and ACTIVE trials, and electroencephalography was employed to derive stimulus-elicited P3 component. Finger prick blood glucose levels were collected at baseline, 0.5 h, 1 h, and 3.5 h during the trials.

RESULTS

While no significant differences were found in inhibitory control performances between trials, greater P3 amplitude was found in the ACTIVE trial relative to the SIT trial (p = .041). Lower postprandial blood glucose iAUC was found in ACTIVE trial compared to SIT trial (p = .028), and this was correlated with the elevation of P3 amplitude (r = - 0.521, p = .023).

CONCLUSION

Breaking up sitting acutely facilitates neuroelectric indices of attentional processing, which is associated with the optimal postprandial blood glucose control.

Factors Associated With Physical Activity in Alzheimer's Disease: A Cross-Sectional Study of Individuals and Their Caregivers

INTRODUCTION

Physical activity (PA) is associated with better outcomes in individuals living with Alzheimer's and related dementia (ADRD). We examined environmental, intra-, and interpersonal correlates of PA for persons living with ADRD.

METHODS

PA (accelerometry), cognitive function, physical function, and sociodemographic factors were collected in adults with ADRD and their caregivers. Spearman's correlations and generalized linear models were used to evaluate factors associated with PA of persons living with ADRD.

RESULTS

Valid data were obtained from 65 pairs of adults living with ADRD (73.6 ± 8.4 years, 39.4% female) and caregivers (69.4 ± 9.4 years, 69.2% female, 93.8% spouse). Moderate-to-vigorous PA (MVPA) and light PA of persons living with ADRD were correlated with upper and lower body strength, aerobic fitness, and agility. MVPA and sedentary time of persons living with ADRD were associated with that of their caregiver.

CONCLUSION

Physical function and caregiver PA may be targets for interventions in those living with ADRD.

Interrupting sitting with moderate-intensity physical activity breaks improves cognitive processing speed in adults with overweight and obesity: Findings from the SITLess pilot randomized crossover trial

INTRODUCTION

Prolonged sitting can acutely reduce working memory (WM) in individuals with overweight and obesity (OW/OB) who show executive function deficits. Interrupting prolonged sitting with brief PA bouts may counter these effects. However, the benefits of such interventions on behavioral and neuroelectric indices of WM and whether neurocognitive responses are associated with postprandial glycemic responses in young and middle-aged adults with OW/OB remain unknown. To address this gap, this study examined the acute effects of interrupting three-hour prolonged sitting every 30 min with 3.5-min moderate-intensity physical activity (MPA) bouts (MPA + SIT condition) relative to sedentary social interaction condition (SOC + SIT) on behavioral measures of WM and the P3b component of event-related potentials (ERP) in young and middle-aged adults with OW/OB.

METHOD

Nineteen adults with OW/OB (63 % females; 29.9 ± 7.5 years; BMI = 30.0 ± 3.64 kg*m-2) were included in the SITLess pilot randomized crossover trial. Choice RT and WM were measured before, after, and four times during each condition with 1- and 2-back letter tasks. They were expressed as the incremental area under the curve (iAUC). Choice RT was expressed as d-prime, target, and nontarget accuracy, and RT on the 1-back and nontarget RT on the 2-back task. WM was expressed as d-prime, target accuracy, and RT on the 2-back task. The amplitude of the P3b-ERP component was used to measure attentional resource allocation during both tasks; the P3b-ERP fractional area latency measured cognitive processing before and after each condition. Two-hour postprandial glycemic responses (expressed as iAUC) were measured using an oral glucose tolerance test (OGTT). Time (pre, post) x Condition (MPA + SIT vs. SOC + SIT) interactions and the main effect of Condition (iAUCs) were tested using Linear Mixed Models.

RESULTS

No significant intervention effects on glucose were noted (p = 0.74). Compared to SOC + SIT, MPA + SIT resulted in shorter 1-back target P3b latency (F(1, 17.0) = 5.14, p = 0.037; Mdiff = -9.77, SE = 4.31 ms, 95%CI: -18.9, -0.68) at post-test. No effects on behavioral measures were noted (ps ≥ 0.06). However, the between-condition difference in 1-back P3b latency correlated positively with the between-condition difference in RTs on 1-back;shorter P3b latency was related to shorter RTs in the MPA + SIT relative to SOC + SIT (r = 0.65 and 0.55 for target and nontarget trials, ps ≤ 0.02).

CONCLUSION

Interrupting sitting with short MPA bouts can enhance some aspects of cognitive processing in adults with OW/OB. Future studies are needed to better understand behavioral responses to interrupting prolonged sitting with MPA bouts and the underlying mechanisms.

Improving brain health via the central executive network

Cognitive and physical stress have significant effects on brain health, particularly through their influence on the central executive network (CEN). The CEN, which includes regions such as the dorsolateral prefrontal cortex, anterior cingulate cortex and inferior parietal lobe, is central to managing the demands of cognitively challenging motor tasks. Acute stress can temporarily reduce connectivity within the CEN, leading to impaired cognitive function and emotional states. However a rebound in these states often follows, driven by motivational signals through the mesocortical and mesolimbic pathways, which help sustain inhibitory control and task execution. Chronic exposure to physical and cognitive challenges leads to long-term improvements in CEN functionality. These changes are supported by neurochemical, structural and systemic adaptations, including mechanisms of tissue crosstalk. Myokines, adipokines, anti-inflammatory cytokines and gut-derived metabolites contribute to a biochemical environment that enhances neuroplasticity, reduces neuroinflammation and supports neurotransmitters such as serotonin and dopamine. These processes strengthen CEN connectivity, improve self-regulation and enable individuals to adopt and sustain health-optimizing behaviours. Long-term physical activity not only enhances inhibitory control but also reduces the risk of age-related cognitive decline and neurodegenerative diseases. This review highlights the role of progressive physical stress through exercise as a practical approach to strengthening the CEN and promoting brain health, offering a strategy to improve cognitive resilience and emotional well-being across the lifespan.

Improving locomotor performance with motor imagery and tDCS in young adults

The study aimed to assess the feasibility and potential efficacy of a non-motor intervention utilizing motor imagery (MI) and transcranial direct current stimulation (tDCS) to enhance motor function. The research involved a double-blind, randomized, controlled trial with three groups: MIActive, MISham, and Control. Participants engaged in a cognitively demanding obstacle course, with time and prefrontal activation (ΔO2Hb and ΔHHb) measured across three-time points (Baseline, Post-test, 1-week follow-up). Following a pretest, active or sham tDCS was administered during an MI session, while the Control group did not receive this intervention. The MIActive group showed significant improvements in time-to-completion immediately after the intervention and one week later. Additionally, ΔO2Hb levels were lower in the MIActive group than in the other groups. These findings suggest that the combination of MI and tDCS could lead to motor improvements. The study outcomes support the feasibility and initial effectiveness of using MI and tDCS as a non-motor intervention to enhance motor outcomes in short and medium terms. Further research is recommended to explore the impact of this intervention in individuals with existing motor impairments. This study contributes to the growing body of evidence on the potential of non-motor interventions to induce neuroplastic changes that improve motor function. Clinical trial registration: ClinicalTrials.gov, identifier NCT06414213 16/05/2024.

Targeting Cognitive Resilience through Prebiotics: A Focused Perspective

This perspective article is a product of the work of an expert group within the Prebiotic Task Force convened by the International Life Sciences Institute Europe, a non-profit organization that brings together experts from academia, industry, and public service to catalyze nutrition science for public benefit. An expert group was conceived in October 2023 to discuss the evidence base on the use of prebiotics to promote cognitive functioning, with a focus on highlighting knowledge gaps and proposing a list of recommendations to guide this specific area of research forward. To address this, we evaluated existing systematic reviews and meta-analyses of human intervention studies that examine the effects of prebiotics on cognitive functioning. These are predominantly conducted in healthy participants under basal conditions and have, to date, revealed limited effects. In this perspective, we propose that prebiotics should be investigated as agents to promote cognitive resilience by testing their effects on cognitive performance under certain cognition-taxing factors that individuals encounter across their lifespan. These include stress, poor sleep outcomes, sedentary behavior, and unhealthy dietary patterns, all of which have been shown to be associated with altered microbiome and impact global cognition or specific cognitive domains. In addition, we recommend identifying vulnerable populations that are either subclinical or that struggle chronically or periodically with 1 or more cognition-taxing factors, to better uncover the boundary conditions for prebiotic effectiveness. By broadening the scope of research to include diverse populations and challenging conditions in daily life or experimental settings, we can expand our understanding of the role of prebiotics not only in cognitive health or impairment, but also as potential preventative agents that may promote cognitive resilience during aging and in response to various lifestyle-related challenges.

Sex differences in the associations of accelerometer-determined physical activity with physical and cognitive function in older adults living in long-term care

Older adults residing in long-term care often experience declines in physical and cognitive functions despite the access to in-house physical activity (PA) programs. This study aimed to evaluate the associations of PA with physical function and global cognitive function in older adults living in long-term care, while examining potential sex differences. A cross-sectional analysis of baseline data from a two-arm cluster randomized controlled trial was conducted, involving 67 participants (34 men, 33 women). PA levels were assessed using tri-axial accelerometers. Physical function, including muscular strength, postural sway, and Short Physical Performance Battery (SPPB) and cognitive function were measured. Spearman correlation analysis revealed no significant associations between PA metrics and muscular strength, postural sway, or global cognitive function across the entire samples (p ≥ 0.091). Multiple linear regression models were developed for the entire sample, males, and females to examine the associations between PA and physical function measures and global cognitive function. After adjustments for confounders, light PA was significantly associated with higher SPPB sub-scores (gait: β = 0.600, p < 0.001; sit-to-stand: β = 0.574, p < 0.001), faster usual gait speed (β = 0.659, p = 0.012), and shorter sit-to-stand times (β = -0.305, p = 0.041) across the whole sample. Similar significant associations were observed in males between light PA and SPPB scores (total: β = 0.319, p = 0.040; gait: β = 0.532, p < 0.001; sit-to-stand: β = 0.417, p = 0.009), usual gait speed (β = 0.762, p = 0.017), and sit-to-stand times (β = -0.677, p < 0.001). In females, a significant association was found between light PA and global cognitive function (β = 0.319, p = 0.012) after adjusting for confounders. This study highlights sex differences in the association of accelerometer-determined PA with physical and cognitive function in older adults living in long-term care, with LPA showing beneficial effects, especially for physical function in males and for cognitive function in females.

The Hidden Dangers of Sedentary Living: Insights into Molecular, Cellular, and Systemic Mechanisms

With the aging of the global population, neurodegenerative diseases are emerging as a major public health issue. The adoption of a less sedentary lifestyle has been shown to have a beneficial effect on cognitive decline, but the molecular mechanisms responsible are less clear. Here we provide a detailed analysis of the complex molecular, cellular, and systemic mechanisms underlying age-related cognitive decline and how lifestyle choices influence these processes. A review of the evidence from animal models, human studies, and postmortem analyses emphasizes the importance of integrating physical exercise with cognitive, multisensory, and motor stimulation as part of a multifaceted approach to mitigating cognitive decline. We highlight the potential of these non-pharmacological interventions to address key aging hallmarks, such as genomic instability, telomere attrition, and neuroinflammation, and underscore the need for comprehensive and personalized strategies to promote cognitive resilience and healthy aging.

GABA, Aging and Exercise: Functional and Intervention Considerations

The global growth of an aging population is expected to coincide with an increase in aging-related pathologies, including those related to brain health. Thus, the potential for accelerated cognitive health declines due to adverse aging is expected to have profound social and economic implications. However, the progression to pathological conditions is not an inevitable part of aging. In fact, engaging in activities that improve cardiovascular fitness appears to be a means that offers the benefits of maintaining and/or improving cognitive health in older age. However, to date, the underlying mechanisms responsible for improved central nervous system health and function with exercise are not yet fully elucidated. Consequently, there is considerable interest in studies aimed at understanding the neurophysiological benefits of exercise on aging. One such area of study suggests that the improvements in brain health via exercise are, in part, driven by the recovery of inhibitory processes related to the neurotransmitter gamma-aminobutyric acid (GABA). In the present review, we highlight the opposing effects of aging and exercise on cortical inhibition and the GABAergic system's functional integrity. We highlight these changes in GABA function by reviewing work with in vivo measurements: transcranial magnetic stimulation (TMS) and magnetic resonance spectroscopy (MRS). We also highlight recent and significant technological and methodological advances in assessing the GABAergic system's integrity with TMS and MRS. We then discuss potential future research directions to inform mechanistic GABA study targeted to improve health and function in aging. We conclude by highlighting the significance of understanding the effects of exercise and aging, its influence on GABA levels, and why a better understanding is crucial to allow for more targeted and effective interventions aimed to ultimately improve age-related decline in aging.

Ecological Momentary Intervention to Replace Sedentary Time With Physical Activity to Improve Executive Function in Midlife and Older Latino Adults: Pilot Randomized Controlled Trial

BACKGROUND

Exercise interventions often improve moderate to vigorous physical activity, but simultaneously increase sedentary time due to a compensatory resting response. A higher level of sedentary time is associated with a lower level of executive function, while increased moderate to vigorous physical activity is associated with improved global cognition and working memory among Latino adults. Latino adults are the fastest-growing minority group in the United States and are at high risk for cognitive decline, spend more time sedentary compared to non-Hispanic populations, and engage in low levels of physical activity. Interventions that are culturally appropriate for Latino adults to replace sedentary time with physical activity are critically needed.

OBJECTIVE

This study aims to develop and test the feasibility and acceptability of an ecological momentary intervention (EMI; delivered in real time) that is individually designed to replace sedentary time with physical activity in Latino adults.

METHODS

This pilot study randomized 39 (n=26, 67% female; mean age 61, SD 5.8 years) community-dwelling, Spanish-speaking Latino adults (1:1 allocation) to either a 6-week EMI program designed to replace sitting time with physical activity (20/39, 51%) or physical activity guidelines education (19/39, 49%). The program was conducted on the web and in Spanish. The intervention was individualized based on individual interview responses. The intervention included the use of a Fitbit activity monitor, weekly didactic phone meetings, interactive tools (SMS text messages), and coach-delivered feedback. Feasibility and acceptability were assessed via study satisfaction (Likert scales), motivation (ecological momentary assessment), retention, and compliance. Sedentary time and physical activity were assessed via 7-day actigraphy. Cognitive performance was assessed via the trail making test part A and B (part B=executive function) and via the National Institutes of Health Toolbox remote cognitive assessment. Statistical analysis included a linear model on change score from baseline, adjusting for age, sex, and education, emphasizing effect size.

RESULTS

Participant satisfaction with EMI was high (9.4/10), with a high degree of motivation to replace sitting time with physical activity (9.8/10). The intervention compliance rate was 79% with low difficulty using the Fitbit (1.7/10). Weekly step count increased in the intervention group by 5543 steps (group difference: d=0.54; P=.05) and sedentary time decreased by a mean 348 (SD 485) minutes (group difference: d=0.47; P=.24) compared to controls, with moderately strong effect sizes. The trail making test part B improved in the intervention group (mean -35.26, SD 60.35 seconds), compared to the control group (mean 7.19, SD 46 seconds; group difference: d=0.74; P=.01). No group differences were observed in other cognitive measures.

CONCLUSIONS

An individualized EMI designed for midlife and older Latino adults has the potential to replace sitting time with physical activity and improve executive functioning. The intervention was feasible and well received with a high degree of satisfaction.

TRIAL REGISTRATION

ClinicalTrials.gov NCT04507464; https://tinyurl.com/44c4thk5.

Musical Activity Engagement, Depressive Symptoms, Physical Activity, and Cognitive Function in People With Type 2 Diabetes

BACKGROUND

Music interventions have beneficial effects on cognitive function and related risk factors, such as depressive symptoms and behavior of exercise participation. However, little research has been conducted on music's effects on people with type 2 diabetes, and evidence of the effect remains inconclusive in this population.

OBJECTIVES

Guided by the theory of music, mood, and movement (MMM), this exploratory study aimed to examine the direct and indirect effects of musical activity engagement, depressive symptoms, and physical activity on cognitive function in people with type 2 diabetes.

METHODS

The present study is a secondary data analysis using the cross-sectional data collected from the Memory, Attention, and Problem-Solving Skills for Persons With Diabetes trial conducted between 2021 and 2023. Data were collected using self-reported questionnaires and a computerized cognitive assessment tool. A total of 189 people with type 2 diabetes and subjective cognitive decline were included in the study. Path analysis was conducted using IBM SPSS AMOS to examine the pathways of the proposed conceptual framework.

RESULTS

The study results partially support the MMM model for subjective cognitive function but not objective cognitive function. The path model demonstrated the significant direct effects of musical activity engagement on physical activity, physical activity on subjective cognitive function, and depressive symptoms on physical activity as well as on subjective cognitive function. There was a significant indirect effect of musical activity engagement on subjective cognitive function through physical activity-which fully mediated this relationship. However, no significant direct effect of musical activity engagement on depressive symptoms and subjective cognitive function was found.

DISCUSSION

The findings suggest that regular assessment of the presence of depressive symptoms and physical activity participation should be done in people with type 2 diabetes to identify potential modifiable factors and develop targeted interventions for cognitive health promotion. Also, our findings provide insights into the potential use of music to facilitate physical activity and manage cognitive health in people with type 2 diabetes. This study partially supports the MMM model; however, more research with a rigorous study design and larger sample size is needed to better understand the relationships among musical activity engagement, depressive symptoms, physical activity, and cognitive function.

Effect of physical activity breaks during prolonged sitting on vascular outcomes: A scoping review

Emerging evidence claims the vascular benefits of varied frequency and duration of physical activity (PA) breaks, whereas the efficacy of varied intensity remains unexplored. We aimed to collate and summate the studies investigating the PA breaks at various intensities on vascular protection. Seven electronic databases were searched for potential studies till Jan 31, 2022. The eligible studies should have administered PA breaks of differing intensities in prolonged sitting postures and explored regional vascular changes [flow mediated dilation (FMD), shear stress, diameter, and blood flow] using ultrasound and novel outcome markers. Two independent reviewers assessed the studies for eligibility after abstract and full-text screen, and appropriate data were extracted to summarise vascular protective effects with PA breaks. Our findings reveal adverse regional vascular outcomes with prolonged sitting (FMD ≈ -1.5%, diameter ≈ -0.06 mm), whereas PA breaks of any intensity were found to improve endothelial functions (FMD ≈ +0.5%, diameter ≈ +0.1 mm, shear ≈ +13 s-1) and mitigate the adverse effects associated with prolonged sitting. Compared with high-intensity activity, low-intensity PA breaks alleviate arterial stiffness and endothelial dysfunction risks.

Leisure-time physical activity as a key protective factor against cognitive decline in older adults: an isotemporal substitution analysis

This study aimed to test hypothesized effects of replacing sedentary behavior with moderate-to-vigorous physical activity, sleep, and different domains of physical activity by equivalent amounts on suggestive cognitive decline in an older adult population. This was a cross-sectional study including 473 older adults aged ≥ 60 years. Cognitive decline was assessed using the Mini-Mental Health Examination. Physical activity, its different domains and the time of exposure to sedentary behavior were assessed using the International Physical Activity Questionnaire. For data analysis, two isotemporal substitution models were constructed using Poisson regression. The first model tested the effect of sleep time, sedentary behavior, and moderate-to-vigorous physical activity on cognitive decline. The second model was used to determine the effect of physical activity domains (leisure, work, transport, and home), sleep time, and sedentary behavior on cognitive decline. Physical activity during leisure time was protective against cognitive decline among all domains tested, replacing sedentary behavior, sleep, and transport. Conversely, substitution of the leisure domain for sedentary behavior, sleep, and transport was considered a risk factor for cognitive decline. Leisure time proved to be a strong protective factor in reducing the risk of cognitive decline, and it is necessary to encourage and stimulate public policies that include it.

From "online brains" to "online lives": understanding the individualized impacts of Internet use across psychological, cognitive and social dimensions

In response to the mass adoption and extensive usage of Internet-enabled devices across the world, a major review published in this journal in 2019 examined the impact of Internet on human cognition, discussing the concepts and ideas behind the "online brain". Since then, the online world has become further entwined with the fabric of society, and the extent to which we use such technologies has continued to grow. Furthermore, the research evidence on the ways in which Internet usage affects the human mind has advanced considerably. In this paper, we sought to draw upon the latest data from large-scale epidemiological studies and systematic reviews, along with randomized controlled trials and qualitative research recently emerging on this topic, in order to now provide a multi-dimensional overview of the impacts of Internet usage across psychological, cognitive and societal outcomes. Within this, we detail the empirical evidence on how effects differ according to various factors such as age, gender, and usage types. We also draw from new research examining more experiential aspects of individuals' online lives, to understand how the specifics of their interactions with the Internet, and the impact on their lifestyle, determine the benefits or drawbacks of online time. Additionally, we explore how the nascent but intriguing areas of culturomics, artificial intelligence, virtual reality, and augmented reality are changing our understanding of how the Internet can interact with brain and behavior. Overall, the importance of taking an individualized and multi-dimensional approach to how the Internet affects mental health, cognition and social functioning is clear. Furthermore, we emphasize the need for guidelines, policies and initiatives around Internet usage to make full use of the evidence available from neuroscientific, behavioral and societal levels of research presented herein.

Sedentary behavior and lifespan brain health

Higher levels of physical activity are known to benefit aspects of brain health across the lifespan. However, the role of sedentary behavior (SB) is less well understood. In this review we summarize and discuss evidence on the role of SB on brain health (including cognitive performance, structural or functional brain measures, and dementia risk) for different age groups, critically compare assessment approaches to capture SB, and offer insights into emerging opportunities to assess SB via digital technologies. Across the lifespan, specific characteristics of SB (particularly whether they are cognitively active or cognitively passive) potentially act as moderators influencing the associations between SB and specific brain health outcomes. We outline challenges and opportunities for future research aiming to provide more robust empirical evidence on these observations.

Midlife physical activity engagement is associated with later-life brain health

The relationship between midlife physical activity (PA), and cognition and brain health in later life is poorly understood with conflicting results from previous research. Investigating the contribution of midlife PA to later-life cognition and brain health in high-risk populations will propel the development of health guidance for those most in need. The current study examined the association between midlife PA engagement and later-life cognition, grey matter characteristics and resting-state functional connectivity in older individuals at high-risk for Alzheimer's disease. The association between midlife PA and later-life cognitive function was not significant but was moderated by later-life PA. Meanwhile, greater midlife moderate-to-vigorous PA was associated with greater grey matter surface area in the left middle frontal gyrus. Moreover, greater midlife total PA was associated with diminished functional connectivity between bilateral middle frontal gyri and middle cingulum, supplementary motor areas, and greater functional connectivity between bilateral hippocampi and right cerebellum, Crus II. These results indicate the potentially independent contribution of midlife PA to later-life brain health.

Breaking prolonged sitting increases 24-h physical activity and self-perceived energy levels but does not acutely affect cognition in healthy adults

INTRODUCTION

It is unknown whether predetermined (un)interrupted sitting within a laboratory setting will induce compensatory changes in human behaviours (energy intake and physical activity) once people return to a free-living environment. The effects of breaking up prolonged sitting on cognition are also unclear.

METHODS

Twenty-four (male = 13) healthy participants [age 31 ± 8 y, BMI 22.7 ± 2.3 kg/m2 (mean ± SD)] completed 320 min mixed-feeding trials under prolonged sitting (SIT) or with 2 min walking at 6.4 km/h every 20 min (ACTIVE), in a randomised crossover design. Human behaviours were recorded post-trial under free-living conditions until midnight. Cognitive performance was evaluated before and immediately after SIT and ACTIVE trials. Self-perceived sensations (appetite, energy and mood) and finger prick blood glucose levels were collected at regular intervals throughout the trials.

RESULTS

There were no differences between trials in eating behaviour and spontaneous physical activity (both, p > 0.05) in free-living conditions, resulting in greater overall total step counts [11,680 (10740,12620) versus 6049 (4845,7253) steps] and physical activity energy expenditure (PAEE) over 24-h period in ACTIVE compared to SIT (all, p < 0.05). Greater self-perceived levels of energy and lower blood glucose iAUC were found in ACTIVE trial compared to SIT trial (both, p < 0.05). No differences were found in cognitive performance between trials (all, p > 0.05).

CONCLUSION

Breaking up sitting does not elicit subsequent behavioural compensation, resulting in greater 24-h step counts and PAEE in healthy adults. Breaking up sitting reduces postprandial glucose concentrations and elicits greater self-perceived energy levels, but these positive effects do not acutely translate into improved cognitive function.

Nutritional Status and Physical Exercise Are Associated with Cognitive Function in Chinese Community-Dwelling Older Adults: The Role of Happiness

We aim to assess the relationship between nutrition status, physical exercise, and cognitive function and particularly examine how happiness modifies and mediates the relationship, among 699 seniors aged 60 and above in Shanghai, China. Linear regression models were used to validate the effects of nutrition and exercise on cognitive function and to test their interaction effects with happiness. When the interactions were significant, stratified analyses in sub-groups were conducted. Mediation effects of happiness were examined using two-step causal mediation models. We confirmed that better nutrition (p < 0.001) and exercise (p = 0.009) were significantly associated with less cognitive decline. Furthermore, the effects of nutrition and exercise on cognitive decline were significant in the unhappy (happiness < 20) (p < 0.001) and younger (age < 74) sub-groups (p = 0.015). Happiness partially mediated 11.5% of the negative association of cognitive decline with nutrition (p = 0.015) and 23.0% of that with exercise (p = 0.017). This study suggests that happiness moderates and partially mediates the effects of exercise and nutrition on cognitive status. The beneficial effects of exercise and nutrition were stronger in less happy or younger seniors. Future intervention studies are required to confirm this path relationship.

Sensing the impact of extreme heat on physical activity and sleep

Introduction

This study assesses the person-specific impact of extreme heat on low-income households using wearable sensors. The focus is on the intensive and longitudinal assessment of physical activity and sleep with the rising person-specific ambient temperature.

Methods

This study recruited 30 participants in a low-income and predominantly Black community in Houston, Texas in August and September of 2022. Each participant wore on his/her wrist an accelerometer that recorded person-specific ambient temperature, sedentary behavior, physical activity intensity (low and moderate to vigorous), and sleep efficiency 24 h over 14 days. Mixed effects models were used to analyze associations among physical activity, sleep, and person-specific ambient temperature.

Results

The main findings include increased sedentary time, sleep impairment with the rise of person-level ambient temperature, and the mitigating role of AC.

Conclusions

Extreme heat negatively affects physical activity and sleep. The negative consequences are especially critical for those with limited use of AC in lower-income neighborhoods of color. Staying home with a high indoor temperature during hot days can lead to various adverse health outcomes including accelerated cognitive decline, higher cancer risk, and social isolation.

The effectiveness of a 6-month intervention with sit-stand workstation in office workers: Results from the SUFHA cluster randomized controlled trial

BACKGROUND

Prolonged periods of sitting have been linked to negative health outcomes. Implementation of sit-stand desks in the workplace has been one strategy to reduce prolonged sitting.

OBJECTIVE

To assess the effectiveness of sit-stand workstations on reducing sitting time and improving other health outcomes of office-based workers.

METHODS

39 Portuguese office workers were randomized into a 6-month parallel-group cluster RCT consisting by the implementation of sit-stand desks in the workplace. The primary outcome of sitting time was assessed using ActivPAL. Secondary outcomes included biometric, psychological, and diet-related variables. All outcomes were assessed at baseline and 6 months for the whole sample and at 3 months for a sub-sample of the intervention group (n = 11).

RESULTS

No significant time*group interaction was found for the primary or secondary outcomes, apart from waist circumference favoring the control group (Δ-1.81 cm, pinteraction = 0.04). There were significant changes within the intervention group for sitting time (-44.0 min/day), prolonged sitting (>30 min) (-45.3 min/day) and standing time (51.7 min/day) at 3 months in the sub-sample and in prolonged sitting (>30 min) (-26 min/day) in the full intervention group (p < 0.05). Changes were also observed within the intervention group for percent body fat (Δ-3.7%) and ratings of quality of life (Δ2.2), musculoskeletal discomfort (Δ-4.9), overall fatigue (Δ-2.2), and the need for recovery after work (Δ-1.7) at 6-month follow-up (p < 0.05).

CONCLUSION

Although not being effective for reducing sitting time, the implementation of sit-stand desks in the Portuguese workspace was shown to be feasible over the long term, received well by users, and may offer other health benefits.

TRIAL REGISTRATION

OSF Registration, OSF.IO/JHGPW. Registered 15 November 2022. https://doi.org/10.17605/OSF.IO/JHGPW.

Sex-specific blood biomarkers linked to memory changes in middle-aged adults: The Framingham Heart Study

The relationship between sex-specific blood biomarkers and memory changes in middle-aged adults remains unclear. We aimed to investigate this relationship using the data from the Framingham Heart Study (FHS). We conducted association analysis, partial correlation analysis, and causal dose-response curves using blood biomarkers and other data from 793 middle-aged participants (≤ 60 years) from the FHS Offspring Cohort. The results revealed associations of adiponectin and fasting blood glucose with midlife memory change, along with a U-shaped relationship of high-density lipoprotein cholesterol with memory change. No significant associations were found for the other blood biomarkers (e.g., amyloid beta protein 42) with memory change. To our knowledge, this is the first sex-specific network analysis of blood biomarkers related to midlife memory change in a prospective cohort study. Our findings highlight the importance of targeting cardiometabolic risks and the need to validate midlife-specific biomarkers that can accelerate the development of primary preventive strategies.

Exploratory study of the acute and mid-term effects of using a novel dynamic meeting environment (Aeris®) on cognitive performance and neurophysiological responses

The purpose of the present study was to assess the acute and mid-term effects of the dynamic aeris®-meeting- environment on brain activity, cognitive performance, heart rate variability (HRV), sleepiness, mental workload (EEG-MWI), as well as local experienced discomfort (LED) in healthy adults. Twenty-four healthy adults (16 females, age: 25.2 ± 3.1 years old) were randomly assigned to either the control (i.e., conventional meeting environment, CG) or experimental (Aeris® dynamic meeting-environment, DG) group with a 1:1 allocation. Participants reported to the laboratory on two test sessions separated by a 2-week intervention period (5 meetings of 90 min each week). Spontaneous resting EEG and HRV activities, as well as attentional (D2-R test) and vigilance (PVT) cognitive performances, sleepiness perceptions, and EEG-MWI, were recorded at the beginning of each test session and immediately following the 90-min meeting. The LED was measured pre- and post-intervention. The changes (Δ) from pre- to post-90 min meeting and from pre- to post- intervention were computed to further examine the acute and mid-term effects, respectively. Compared to the CG, the DG showed higher Δ (pre-post 90 min-meeting) in fronto-central beta (z = -2.41, p = 0.016, d = 1.10) and gamma (z = -2.34, p = 0.019, d = 0.94) frequencies at post-intervention. From pre- to post-intervention, only the DG group showed a significant increase in fronto-central gamma response (Δ) to the meeting session (z = -2.09, p = 0.04, d = 1.08). The acute use of the Aeris®-meeting-environment during the 90-min meeting session seems to be supportive for (i) maintaining vigilance performance, as evidenced by the significant increase in N-lapses from pre- to post-90 min session only in the CG (p = 0.04, d = 0.99, Δ = 2.5 ± 3 lapses), and (ii) improving alertness, as evidenced by the lower sleepiness score (p = 0.05, d = -0.84) in DG compared to CG. The mid-term use of such an environment showed to blind the higher baseline values of EEG-MWI recorded in DG compared to CG (p = 0.01, d = 1.05) and may prevent lower-back discomfort (i.e., a significant increase only in CG with p = 0.05 and d = 0.78), suggesting a less mentally and physically exhausting meeting in this environment. There were no acute and/or mid-term effects of the dynamic meeting environment on any of the HRV parameters. These findings are of relevance in the field of neuroergonomics, as they give preliminary support to the advantages of meeting in a dynamic office compared to a static office environment.

Physiology of sedentary behavior

Sedentary behaviors (SB) are characterized by low energy expenditure while in a sitting or reclining posture. Evidence relevant to understanding the physiology of SB can be derived from studies employing several experimental models: bed rest, immobilization, reduced step count, and reducing/interrupting prolonged SB. We examine the relevant physiological evidence relating to body weight and energy balance, intermediary metabolism, cardiovascular and respiratory systems, the musculoskeletal system, the central nervous system, and immunity and inflammatory responses. Excessive and prolonged SB can lead to insulin resistance, vascular dysfunction, shift in substrate use toward carbohydrate oxidation, shift in muscle fiber from oxidative to glycolytic type, reduced cardiorespiratory fitness, loss of muscle mass and strength and bone mass, and increased total body fat mass and visceral fat depot, blood lipid concentrations, and inflammation. Despite marked differences across individual studies, longer term interventions aimed at reducing/interrupting SB have resulted in small, albeit marginally clinically meaningful, benefits on body weight, waist circumference, percent body fat, fasting glucose, insulin, HbA1c and HDL concentrations, systolic blood pressure, and vascular function in adults and older adults. There is more limited evidence for other health-related outcomes and physiological systems and for children and adolescents. Future research should focus on the investigation of molecular and cellular mechanisms underpinning adaptations to increasing and reducing/interrupting SB and the necessary changes in SB and physical activity to impact physiological systems and overall health in diverse population groups.

A Potential Role for Sirtuin-1 in Alzheimer's Disease: Reviewing the Biological and Environmental Evidence

Sirtuin-1 (Sirt1), encoded by the SIRT1 gene, is a conserved Nicotinamide adenine dinucleotide (NAD+) dependent deacetylase enzyme, considered as the master regulator of metabolism in humans. Sirt1 contributes to a wide range of biological pathways via several mechanisms influenced by lifestyle, such as diet and exercise. The importance of a healthy lifestyle is of relevance to highly prevalent modern chronic diseases, such as Alzheimer's disease (AD). There is growing evidence at multiple levels for a role of Sirt1/SIRT1 in AD pathological mechanisms. As such, this review will explore the relevance of Sirt1 to AD pathological mechanisms, by describing the involvement of Sirt1/SIRT1 in the development of AD pathological hallmarks, through its impact on the metabolism of amyloid-β and degradation of phosphorylated tau. We then explore the involvement of Sirt1/SIRT1 across different AD-relevant biological processes, including cholesterol metabolism, inflammation, circadian rhythm, and gut microbiome, before discussing the interplay between Sirt1 and AD-related lifestyle factors, such as diet, physical activity, and smoking, as well as depression, a common comorbidity. Genome-wide association studies have explored potential associations between SIRT1 and AD, as well as AD risk factors and co-morbidities. We summarize this evidence at the genetic level to highlight links between SIRT1 and AD, particularly associations with AD-related risk factors, such as heart disease. Finally, we review the current literature of potential interactions between SIRT1 genetic variants and lifestyle factors and how this evidence supports the need for further research to determine the relevance of these interactions with respect to AD and dementia.

Accelerometer-measured physical activity and sitting with incident mild cognitive impairment or probable dementia among older women

INTRODUCTION

Physical activity (PA) is prospectively inversely associated with dementia risk, but few studies examined accelerometer measures of PA and sitting with rigorously-adjudicated mild cognitive impairment (MCI) and dementia risk.

METHODS

We examined the associations of accelerometer measures (PA and sitting) with incident MCI/probable dementia in the Women's Health Initiative (n = 1277; mean age = 82 ± 6 years) RESULTS: Over a median follow-up of 4.2 years, 267 MCI/probable dementia cases were identified. Adjusted Cox regression HRs (95% CI) across moderate-to-vigorous PA (MVPA) min/d quartiles were 1.00 (reference), 1.28 (0.90 to 1.81), 0.79 (0.53 to 1.17), and 0.69 (0.45 to 1.06); P-trend = 0.01. Adjusted HRs (95% CI) across steps/d quartiles were 1.00 (reference), 0.73 (0.51 to 1.03), 0.64 (0.43 to 0.94), and 0.38 (0.23 to 0.61); P-trend < 0.001. The HR (95% CI) for each 1-SD increment in MVPA (31 min/d) and steps/d (1865) were 0.79 (0.67 to 0.94) and 0.67 (0.54 to 0.82), respectively. Sitting was not associated with MCI/probable dementia.

DISCUSSION

Findings suggest ≥ moderate intensity PA, particularly stepping, associates with lower MCI and dementia risk.

HIGHLIGHTS

Few studies have examined accelerometer-measured physical activity, including steps, and sitting with incident ADRD. Moderate-to-vigorous physical activity and steps, but not light physical activity or sitting, were inversely associated with lower ADRD risk. Among older women, at least moderate intensity physical activity may be needed to reduce ADRD risk.

Brain metabolism in Alzheimer's disease: biological mechanisms of exercise

Alzheimer's disease (AD) is a major subtype of neurodegenerative dementia caused by long-term interactions and accumulation of multiple adverse factors, accompanied by dysregulation of numerous intracellular signaling and molecular pathways in the brain. At the cellular and molecular levels, the neuronal cellular milieu of the AD brain exhibits metabolic abnormalities, compromised bioenergetics, impaired lipid metabolism, and reduced overall metabolic capacity, which lead to abnormal neural network activity and impaired neuroplasticity, thus accelerating the formation of extracellular senile plaques and intracellular neurofibrillary tangles. The current absence of effective pharmacological therapies for AD points to the urgent need to investigate the benefits of non-pharmacological approaches such as physical exercise. Despite the evidence that regular physical activity can improve metabolic dysfunction in the AD state, inhibit different pathophysiological molecular pathways associated with AD, influence the pathological process of AD, and exert a protective effect, there is no clear consensus on the specific biological and molecular mechanisms underlying the advantages of physical exercise. Here, we review how physical exercise improves crucial molecular pathways and biological processes associated with metabolic disorders in AD, including glucose metabolism, lipid metabolism, Aβ metabolism and transport, iron metabolism and tau pathology. How metabolic states influence brain health is also presented. A better knowledge on the neurophysiological mechanisms by which exercise improves AD metabolism can contribute to the development of novel drugs and improvement of non-pharmacological interventions.

Providing office workers with height-adjustable workstation to reduce and interrupt workplace sitting time: protocol for the Stand Up for Healthy Aging (SUFHA) cluster randomized controlled trial

BACKGROUND

Sedentary behavior (SB) has been linked to several negative health outcomes. Therefore, reducing SB or breaking up prolonged periods of SB improves functional fitness, food consumption, job satisfaction, and productivity. Reducing SB can be achieved by introducing a health-enhancing contextual modification promoted by a sit-stand desk in the workplace. The primary goal will be to test the effectiveness of this intervention in reducing and breaking up SB, while improving health outcomes in office-based workers during a 6-month intervention.

METHODS

A two-arm (1:1), superiority parallel-group cluster RCT will be conducted to evaluate the effectiveness of this intervention in a sample of office-based workers from a university in Portugal. The intervention will consist of a psychoeducation session, motivational prompts, and contextual modification promoted by a sit-stand desk in the workplace for 6 months. The control group will work as usual in their workplace, with no contextual change or prompts during the 6-month intervention. Three assessment points will be conducted in both groups, pre-intervention (baseline), post-intervention, and a 3-month follow-up. The primary outcomes include sedentary and physical activity-related variables, which will be objectively assessed with 24 h monitoring using the ActivPAL for 7 days. The secondary outcomes include (a) biometric indices as body composition, body mass index, waist circumference, and postural inequalities; and (b) psychosocial variables such as overall and work-related fatigue, overall discomfort, life/work satisfaction, quality of life, and eating behavior. Both the primary and secondary outcomes will be assessed at each assessment point.

DISCUSSION

This study will lean on the use of a sit-stand workstation for 6 months, prompted by an initial psychoeducational session and ongoing motivational prompts. We will aim to contribute to this topic by providing robust data on alternating sitting and standing postures in the workplace.

TRIAL REGISTRATION

The trial was prospectively registered, and the details are at: https://doi.org/10.17605/OSF.IO/JHGPW ; Registered 15 November 2022. OSF Preregistration.

How can we modulate aging through nutrition and physical exercise? An epigenetic approach

The World Health Organization predicts that by 2050, 2.1 billion people worldwide will be over 60 years old, a drastic increase from only 1 billion in 2019. Considering these numbers, strategies to ensure an extended "healthspan" or healthy longevity are urgently needed. The present study approaches the promotion of healthspan from an epigenetic perspective. Epigenetic phenomena are modifiable in response to an individual's environmental exposures, and therefore link an individual's environment to their gene expression pattern. Epigenetic studies demonstrate that aging is associated with decondensation of the chromatin, leading to an altered heterochromatin structure, which promotes the accumulation of errors. In this review, we describe how aging impacts epigenetics and how nutrition and physical exercise can positively impact the aging process, from an epigenetic point of view. Canonical histones are replaced by histone variants, concomitant with an increase in histone post-translational modifications. A slight increase in DNA methylation at promoters has been observed, which represses transcription of previously active genes, in parallel with global genome hypomethylation. Aging is also associated with deregulation of gene expression - usually provided by non-coding RNAs - leading to both the repression of previously transcribed genes and to the transcription of previously repressed genes. Age-associated epigenetic events are less common in individuals with a healthy lifestyle, including balanced nutrition, caloric restriction and physical exercise. Healthy aging is associated with more tightly condensed chromatin, fewer PTMs and greater regulation by ncRNAs.

Impact of Breaking up of Sitting Time on Anti-inflammatory Response Induced by Extracellular Vesicles

Physical inactivity and sedentary behaviors (SB) have promoted a dramatic increase in the incidence of a host of chronic disorders over the last century. The breaking up of sitting time (i.e., sitting to standing up transition) has been proposed as a promising solution in several epidemiological and clinical studies. In parallel to the large interest it initially created, there is a growing body of evidence indicating that breaking up prolonged sedentary time (i.e., > 7 h in sitting time) could reduce overall mortality risks by normalizing the inflammatory profile and cardiometabolic functions. Recent advances suggest that the latter health benefits, may be mediated through the immunomodulatory properties of extracellular vesicles. Primarily composed of miRNA, lipids, mRNA and proteins, these vesicles would influence metabolism and immune system functions by promoting M1 to M2 macrophage polarization (i.e., from a pro-inflammatory to anti-inflammatory phenotype) and improving endothelial function. The outcomes of interrupting prolonged sitting time may be attributed to molecular mechanisms induced by circulating angiogenic cells. Functionally, circulating angiogenic cells contribute to repair and remodel the vasculature. This effect is proposed to be mediated through the secretion of paracrine factors. The present review article intends to clarify the beneficial contributions of breaking up sitting time on extracellular vesicles formation and macrophage polarization (M1 and M2 phenotypes). Hence, it will highlight key mechanistic information regarding how breaking up sitting time protocols improves endothelial health by promoting antioxidant and anti-inflammatory responses in human organs and tissues.

Modifiable risk factors of dementia linked to excitation-inhibition imbalance

Recent evidence identifies 12 potentially modifiable risk factors for dementia to which 40% of dementia cases are attributed. While the recognition of these risk factors has paved the way for the development of new prevention measures, the link between these risk factors and the underlying pathophysiology of dementia is yet not well understood. A growing number of recent clinical and preclinical studies support a role of Excitation-Inhibition (E-I) imbalance in the pathophysiology of dementia. In this review, we aim to propose a conceptual model on the links between the modifiable risk factors and the E-I imbalance in dementia. This model, which aims to address the current gap in the literature, is based on 12 mediating common mechanisms: the hypothalamic-pituitary-adrenal (HPA) axis dysfunction, neuroinflammation, oxidative stress, mitochondrial dysfunction, cerebral hypo-perfusion, blood-brain barrier (BBB) dysfunction, beta-amyloid deposition, elevated homocysteine level, impaired neurogenesis, tau tangles, GABAergic dysfunction, and glutamatergic dysfunction. We believe this model serves as a framework for future studies in this field and facilitates future research on dementia prevention, discovery of new biomarkers, and developing new interventions.

Effects of acute slackline exercise on executive function in college students

Background

Physical exercise as an intervention for improving cognitive function, especially executive function, is receiving increasing attention because it is easily accessible, cost-effective and promises many additional health-related benefits. While previous studies focused on aerobic exercise and resistance exercise, recent findings have suggested that exercise with high coordination demand elicits beneficial effects on executive function. We therefore examined the effects of an acute slackline exercise on the executive functions of young adults.

Methods

In a crossover experimental design, 47 healthy participants (21 females), ranging in age from 18 to 27 years (M = 19.17, SD = 1.94) were randomly assigned to different sequences of two conditions (slackline exercise and film-watching). Before and after the 50 min intervention, a modified Simon task was used to assess participants' executive function (inhibitory control and cognitive flexibility).

Results

College students showed better inhibitory control performance as indicated by shorter reaction times following acute slackline exercise than those who participated in the film-watching session. As there was no difference in accuracy between the slackline exercise and film-watching sessions, the shortened reaction time after slackline exercise provides evidence against a simple speed-accuracy trade-off.

Conclusion

Compared with film-watching, acute slackline exercise provides favorable effects on executive function necessitating inhibition in young adults. These findings provide insight into exercise prescription and cognition, and further evidence for the beneficial effects of coordination exercise on executive functions.

Early Chronic Stress Induced Changes within the Locus Coeruleus in Sporadic Alzheimer's Disease

Chronic exposure to stress throughout the lifespan has been the focus of many studies on Alzheimer's disease (AD) because of the similarities between the biological mechanisms involved in chronic stress and the pathophysiology of AD. In fact, the earliest abnormality associated with the disease is the presence of phosphorylated tau protein in locus coeruleus neurons, a brain structure highly responsive to stress and perceived threat. Here, we introduce allostatic load as a useful concept for understanding many of the complex, interacting neuropathological changes involved in the AD degenerative process. In response to chronic stress, aberrant tau proteins that begin to accumulate within the locus coeruleus decades prior to symptom onset appear to represent a primary pathological event in the AD cascade, triggering a wide range of interacting brain changes involving neuronal excitotoxicity, endocrine alterations, inflammation, oxidative stress, and amyloid plaque exacerbation. While it is acknowledged that stress will not necessarily be the major precipitating factor in all cases, early tau-induced changes within the locus coeruleus-norepinephrine pathway suggests that a therapeutic window might exist for preventative measures aimed at managing stress and restoring balance within the HPA axis.

Accelerometer-Measured Sedentary Behavior Patterns, Brain Structure, and Cognitive Function in Dementia-Free Older Adults: A Population-Based Study

BACKGROUND

Sedentary behavior is associated with cognitive impairment, but the neuropathological mechanisms underlying their associations are poorly understood.

OBJECTIVE

To investigate the associations of accelerometer-measured sedentary behavior patterns with brain structure and cognition, and further to explore the potential mechanisms.

METHODS

This community-based study included 2,019 older adults (age≥60 years, 59% women) without dementia derived from participants in the baseline examination of MIND-China (2018-2020). We assessed sedentary parameters using an accelerometer and cognitive function using a neuropsychological test battery. Structural brain markers were assessed on the structural brain MRI scans in a subsample (n = 1,009). Data were analyzed using the general linear, isotemporal substitution, and mediation models.

RESULTS

In the total sample (n = 2,019), adjusting for multiple covariates and moderate-to-vigorous-intensity physical activity, longer mean sedentary bout duration was linearly related with lower z-scores of global cognition, verbal fluency, and memory (ptrend < 0.05), whereas greater total sedentary time was linearly associated with lower z-scores of global cognition, verbal fluency, and memory only among individuals with long sedentary time (>10 h/day) (ptrend < 0.05); Breaking up sedentary time with same amount of light-intensity physical activity was significantly associated with higher verbal fluency and memory z-scores (p < 0.05). In the MRI subsample (n = 1,009), separately entering structural brain MRI markers into the mediation models substantially attenuated the associations of mean sedentary bout duration with global cognition, verbal fluency, and memory z-scores.

CONCLUSION

Prolonged uninterrupted sedentary time is associated with poor global cognition, memory, and verbal fluency among rural older adults, and structural brain markers could partially mediate the association.

Preliminary results of the cross-sectional associations of sedentary behavior and physical activity with serum brain-derived neurotrophic factor in adults with coronary heart disease

This is the first study to analyze the association of accelerometer-measured patterns of habitual physical activity (PA) and sedentary behavior (SB) with serum BDNF in individuals with coronary heart disease. A total of 30 individuals (M = 69.5 years; 80% men) participated in this pre-post study that aimed to test a multi-behavioral intervention. All participants underwent standardized measurement of anthropometric variables, blood collection, self-administered survey, and accelerometer-based measurement of PA and SB over seven days. Serum BDNF concentrations were measured using enzyme-linked immunosorbent assay kit. We applied separate multiple linear regression analysis to estimate the associations of baseline SB pattern measures, light and moderate-to-vigorous PA with serum BDNF (n = 29). Participants spent 508.7 ± 76.5 min/d in SB, 258.5 ± 71.2 min/d in light PA, and 21.2 ± 15.2 min/d in moderate-to-vigorous PA. Per day, individuals had 15.5 ± 3.2 numbers of 10-to-30 min bouts of SB (average length: 22.2 ± 2.1 min) and 3.4 ± 1.2 numbers of > 30 min bouts of SB (average length: 43.8 ± 2.4 min). Regression analysis revealed no significant associations between any of the accelerometer-based measures and serum BDNF. The findings of this study did not reveal an association of accelerometer-measured PA and SB pattern variables with serum BDNF in individuals with coronary heart disease. In addition, our data revealed a considerable variation of PA and SB which should be considered in future studies.

A review of the preclinical and clinical studies on the role of the gut microbiome in aging and neurodegenerative diseases and its modulation

As the world population ages, the burden of age-related health problems grows, creating a greater demand for new novel interventions for healthy aging. Advancing aging is related to a loss of beneficial mutualistic microbes in the gut microbiota caused by extrinsic and intrinsic factors such as diet, sedentary lifestyle, sleep deprivation, circadian rhythms, and oxidative stress, which emerge as essential elements in controlling and prolonging life expectancy of healthy aging. This condition is known as gut dysbiosis, and it affects normal brain function via the brain-gut microbiota (BGM) axis, which is a bidirectional link between the gastrointestinal tract (GIT) and the central nervous system (CNS) that leads to the emergence of brain disorders such as Alzheimer's disease (AD), Parkinson's disease (PD), amyotrophic lateral sclerosis (ALS), and frontotemporal dementia (FTD). Here, we reviewed the role of the gut microbiome in aging and neurodegenerative diseases, as well as provided a comprehensive review of recent findings from preclinical and clinical studies to present an up-to-date overview of recent advances in developing strategies to modulate the intestinal microbiome by probiotic administration, dietary intervention, fecal microbiota transplantation (FMT), and physical activity to address the aging process and prevent neurodegenerative diseases. The findings of this review will provide researchers in the fields of aging and the gut microbiome design innovative studies that leverage results from preclinical and clinical studies to better understand the nuances of aging, gut microbiome, and neurodegenerative diseases.

Do energy expenditure differences across work postures influence cognitive processing speed? A counter-balanced randomised cross-over trial

BACKGROUND

Anecdotal evidence links occupational sedentary behaviour, low energy expenditure (EE) and cognitive dysfunction. Nevertheless, EE across different work postures including active workstations remains unclear and its influence on cognitive processing speed is yet to be established.

OBJECTIVE

We aimed to investigate differences in EE across various work postures and its influence on cognitive processing speed.

METHODS

Sixteen desk-based employees performed simulated work tasks (typing, reading and cognitive tasks) in three different work positions (sitting, standing, and walking) in three different days. EE was measured for three days consecutively for 30-minutes in three simulated working postures using indirect calorimetry. Cognitive processing speed was assessed through computer-based choice reaction times during each work posture. The outcome variables of interest (EE, reaction times and accuracy) were compared between three work postures using repeated measures ANOVA and Pearson correlation.

RESULTS

EE in walking posture was higher (5.57±0.45 Kcal) than sitting (1.07±0.12 Kcal) and standing (1.88±0.42 Kcal). Total EE was significantly higher in walking than standing (35.17±6.86 Kcal) and sitting postures (41.37±8.46 Kcal). We did not find any significant differences in cognitive processing speed between different work postures except within standing work condition (60.22±13.97 ms). Accuracy was found to be reduced in walking compared to sitting (0.76±0.83%) and standing (0.43±0.09%) but not reached significance.

CONCLUSION

Although significant differences in EE were observed between work postures, walking or standing at work did not affect the cognitive processing speed.

Effects of reducing sedentary behaviour duration by increasing physical activity, on cognitive function, brain function and structure across the lifespan: a systematic review protocol

INTRODUCTION

Greater engagement in sedentary behaviours has been related to poorer cognitive functions in epidemiological research. However, the effects of reducing sedentary behaviour duration on cognitive function, brain function, and structure remain poorly understood. This systematic review aims to synthesise the evidence on the effects of reducing sedentary behaviour duration by increasing time spent in physical activity on cognitive function, brain structure and function in apparently healthy children, adolescents and adults.

METHODS AND ANALYSIS

The protocol follows Preferred Reporting Items for Systematic Reviews and Meta-Analyses. The literature search will be conducted (search dates: August-September 2022) across six databases: PubMed, Scopus, Cumulative Index to Nursing and Allied Health Literature (via EBSCO Host), PsycINFO (via ProQuest), SPORTDiscus and Web of Science (Science and Social Science Citation Index). The inclusion criteria are as follows: randomised and non-randomised experimental studies as defined by the Cochrane Handbook, published in English, in peer-reviewed journals, and as theses or dissertations. References of included papers will be screened for additional studies. Acute and chronic interventions targeting children (≥ 4 years), adolescents, younger adults (≥ 18-40 years), middle-aged (40-64 years) and older adults (65+ years) will be eligible. Methodological quality will be assessed with the Effective Public Health Practice Project quality assessment tool for quantitative studies. Qualitative synthesis will be stratified by intervention type (acute vs chronic), intervention content (reducing sedentary time or interrupting prolonged sitting) and outcome (cognitive, brain structure and function).

ETHICS AND DISSEMINATION

No primary data collection will be conducted as part of this systematic review. Study findings will be disseminated through peer-reviewed publications, conference presentations and social media.

PROSPERO REGISTRATION NUMBER

CRD42020200998.

Total Sedentary Time and Cognitive Function in Middle-Aged and Older Adults: A Systematic Review and Meta-analysis

Background

An estimated 47 million people have dementia globally, and around 10 million new cases are diagnosed each year. Many lifestyle factors have been linked to cognitive impairment; one emerging modifiable lifestyle factor is sedentary time.

Objective

To conduct a systematic review and meta-analysis of peer-reviewed literature examining the association between total sedentary time with cognitive function in middle-aged and older adults under the moderating conditions of (a) type of sedentary time measurement; (b) the cognitive domain being assessed; (c) looking at sedentary time using categorical variables (i.e., high versus low sedentary time); and (d) the pattern of sedentary time accumulation (e.g., longer versus shorter bouts). We also aimed to examine the prevalence of sedentary time in healthy versus cognitively impaired populations and to explore how experimental studies reducing or breaking up sedentary time affect cognitive function. Lastly, we aimed to conduct a quantitative pooled analysis of all individual studies through meta-analysis procedures to derive conclusions about these relationships.

Methods

Eight electronic databases (EMBASE; Web of Science; PsycINFO; CINAHL; SciELO; SPORTDiscus; PubMed; and Scopus) were searched from inception to February 2021. Our search included terms related to the exposure (i.e., sedentary time), the population (i.e., middle-aged and older adults), and the outcome of interest (i.e., cognitive function). PICOS framework used middle-aged and older adults where there was an intervention or exposure of any sedentary time compared to any or no comparison, where cognitive function and/or cognitive impairment was measured, and all types of quantitative, empirical, observational data published in any year were included that were published in English. Risk of bias was assessed using QualSyst.

Results

Fifty-three studies including 83,137 participants met the inclusion criteria of which 23 studies had appropriate data for inclusion in the main meta-analysis. The overall meta-analysis suggested that total sedentary time has no association with cognitive function (r = −0.012 [95% CI − 0.035, 0.011], p = 0.296) with marked heterogeneity (I² = 89%). Subgroup analyses demonstrated a significant negative association for studies using a device to capture sedentary time r = −0.035 [95% CI − 0.063, − 0.008], p = 0.012). Specifically, the domains of global cognitive function (r = −0.061 [95% CI − 0.100, − 0.022], p = 0.002) and processing speed (r = −0.067, [95% CI − 0.103, − 0.030], p < 0.001). A significant positive association was found for studies using self-report (r = 0.037 [95% CI − 0.019, 0.054], p < 0.001). Specifically, the domain of processing speed showed a significant positive association (r = 0.057 [95% CI 0.045, 0.069], p < 0.001). For prevalence, populations diagnosed with cognitive impairment spent significantly more time sedentary compared to populations with no known cognitive impairments (standard difference in mean = −0.219 [95% CI − 0.310, − 0.128], p < 0.001).

Conclusions

The association of total sedentary time with cognitive function is weak and varies based on measurement of sedentary time and domain being assessed. Future research is needed to better categorize domains of sedentary behaviour with both a validated self-report and device-based measure in order to improve the strength of this relationship. PROSPERO registration number: CRD42018082384.

Supplementary Information

The online version contains supplementary material available at 10.1186/s40798-022-00507-x.

Psychological-health correlates of physical activity and sedentary behaviour during the COVID pandemic

BACKGROUND

While physical inactivity is associated with adverse psychological outcomes, less is known about the psychological outcomes associated with sedentary behaviour, and specifically, its mentally active and passive forms. The COVID-19 pandemic represents a unique opportunity to study associations between these variables in light of widespread stay-at-home mandates and restrictions on outdoor exercise/social activities. Using a cross-sectional dataset acquired during the COVID-19 pandemic in Australia, we examined whether physical activity and sedentary behaviour were associated with subjective quality of life (sQoL) and subjective cognitive dysfunction, and whether these associations were mediated by depressive symptoms.

METHODS

658 participants (males = 169, females = 489) self-reported data on physical activity and sedentary behaviour in an online survey during May 2020-May 2021. Data on physical activity and sedentary behaviour (both mentally active and passive types) was compared according to whether it was collected during or out of a lockdown period. Regression models were used to test associations of physical activity and sedentary behaviour with sQoL and subjective cognitive dysfunction, and whether these associations were mediated by depression severity.

RESULTS

Physical activity was beneficially associated with sQoL, whereas sedentary behaviour (both total hours and the reduction of mentally active/increase in mentally passive behaviour) was detrimentally associated with sQoL. These associations were mediated by depression severity. Physical activity and sedentary behaviour were also indirectly associated with subjective cognitive dysfunction by virtue of their associations with depression severity.

CONCLUSIONS

There are important differences in the psychological correlates of mentally passive and active sedentary behaviours. Our findings suggest that health promotion strategies should focus on not only increasing physical activity but also reducing passive sedentary behaviours as a means of maintaining good psychological health.

Effect of a 16-week multi-level classroom standing desk intervention on cognitive performance and academic achievement in adolescents

The replacement of traditional classroom desks for active-permissive desks has been tested to reduce sitting time during classes. However, their impact on other domains is still unclear. We aimed to verify the potential effects of a classroom standing desk intervention on cognitive function and academic achievement in 6th-grade students. This was a controlled trial conducted with two classes [intervention (n = 22) and control (n = 27)] from a public school in Lisbon, Portugal. The intervention was carried out for 16 weeks and consisted of multi-level actions (students, parents, and teachers) centered on the implementation of standing desks in the intervention classroom. The control group had traditional classes with no use of standing desks or any other interference/action from the research team. Pre- and post-assessments of executive functions (attention, inhibitory function, memory, and fluid intelligence) and academic achievement were obtained. No differences between groups were found at baseline. Both groups improved (time effect) academic achievement (p < 0.001), memory span (p < 0.001), and inhibitory function (p = 0.008). Group versus time interactions were observed regarding operational memory (intervention: + 18.0% and control: + 41.6%; p = 0.039) and non-verbal fluid intelligence (intervention: − 14.0% and control: + 3.9%; p = 0.017). We concluded that a 16-week classroom standing desk intervention did not improve cognitive performance or academic achievement more than the traditional sitting classes.

Trial registration: ClinicalTrials.gov Identifier (NCT03137836) (date of first registration: 03/05/2017).

Impact of Acute Uninterrupted Sitting on Cerebrovascular Hemodynamics

Reductions in brain blood flow are associated with reduced cognitive function and cerebrovascular disease. Acute periods of uninterrupted sitting can lead to endothelial dysfunction, namely due to a reduction in shear stress and subsequent reduction in nitric oxide bioavailability. Little is known of the impact of sitting on brain health. The purpose was to determine the total brain blood flow response following a 60-minute bout of uninterrupted sitting. Using a parallel design, this study evaluated the impact of 60-minutes of sitting on total brain blood flow. Fifteen participants (n=15; age=24 ± 1yr; BMI=25 ± 1 kg/m2) sat, uninterrupted, for 60-minutes during the SIT protocol. To ascertain the contribution of blood pooling effects on total brain blood flow, ten participants (n=10; age=23±2yr; BMI=27±4 kg/m2) sat in a modified sitting (MOD) for 60-minutes. Finally, thirteen participants (n=13; age=23±3yr; BMI=26±4 kg/m2) remained supine for the duration of the 60-minutes as a time-control (TC). Brain blood flow was quantified through Doppler-ultrasound measurements of blood flow through the internal carotid (ICA) and vertebral (VA) arteries: (ICA blood flow + VA blood flow) × 2. Following the 60-minutes of sitting (SIT), there was a significant reduction in brain blood flow with time (p=0.001, η p 2 =0.05). Total brain blood flow did not significantly change in MOD (p=0.69, η p 2 =0.05) or TC (p=0.06, η p 2 =0.58) conditions. These findings indicate 60-minutes of sitting may alter cerebrovascular hemodynamics characterized by a reduction in total brain blood flow.

Orthostatic intolerance: a handicap of aging or physical deconditioning?

Despite several studies that have been investigated physical inactivity and age-related effects on orthostatic tolerance, impaired hemodynamics and postural balance responses to orthostatic stress are incorrectly attributed to aging or sedentarism alone. The isolated effects from aging and sedentarism should be investigated through comparative studies between senior athletes and age-matched controls, and physical activity assessments on aging follow-up studies. On the other hand, bed rest and space flight studies mimic accelerated physical inactivity or disuse, which is not the same physiological decline provoked by aging alone. Thus, the elementary question is: could orthostatic intolerance be attributed to aging or physical inactivity? The main purpose of this review is to provide an overview of possible mechanisms underlying orthostatic tolerance contrasting the paradigm of aging and/or physical inactivity. The key points of this review are the following: (1) to counterpoint all relevant literature on physiological aspects of orthostatic tolerance; (2) to explore the mechanistic aspects underneath the cerebrovascular, cardiorespiratory, and postural determinants of orthostatic tolerance; and (3) examine non-pharmacological interventions with the potential to counterbalance the physical inactivity and aging effects. To date, the orthostatic intolerance cannot be attributed exclusively with aging since physical inactivity plays an important role in postural balance, neurovascular and cardiorespiratory responses to orthostatic stress. These physiological determinates should be interpreted within an integrative approach of orthostatic tolerance, that considers the interdependence between physiological systems in a closed-loop model. Based on this multisystem approach, acute and chronic countermeasures may combat aging and sedentarism effects on orthostatic tolerance.

Acute effects of physical activity patterns on plasma cortisol and brain-derived neurotrophic factor in relation to corticospinal excitability

Brain-derived neurotrophic factor (BDNF) and cortisol are both capable of modulating synaptic plasticity, but it is unknown how physical activity-induced changes in their plasma levels relate to corticospinal plasticity in humans. Sixteen inactive middle-aged men and women participated in three separate interventions consisting of 3hours prolonged sitting (SIT); 3hours sitting interrupted every 30minutes with frequent short physical activity breaks (FPA); and 2.5hours prolonged sitting followed by 25minutes of moderate intensity exercise (EXE). These 3hour sessions were each followed by a 30min period of paired associative stimulation over the primary motor cortex (PAS). Blood samples were taken and corticospinal excitability measured at baseline, pre PAS, 5min and 30min post PAS. Here we report levels of plasma BDNF and cortisol over three activity conditions and relate these levels to previously published changes in corticospinal excitability of a non-activated thumb muscle. There was no interaction between time and condition in BDNF, but cortisol levels were significantly higher after EXE compared to after SIT and FPA. Higher cortisol levels at pre PAS predicted larger increases in corticospinal excitability from baseline to all subsequent time points in the FPA condition only, while levels of BDNF at pre PAS did not predict such changes in any of the conditions. Neither BDNF nor cortisol modified changes from pre PAS to the subsequent time points, suggesting that the increased corticospinal excitability was not mediated though an augmented effect of the PAS protocol. The relationship between cortisol and plasticity has been suggested to be U-shaped. This is possibly why the moderately high levels of cortisol seen in the FPA condition were positively associated with changes AURC, while the higher cortisol levels seen after EXE were not. A better understanding of the mechanisms for how feasible physical activity breaks affect neuroplasticity can inform the theoretical framework for how work environments and schedules should be designed. DATA AVAILABILITY: Data are available from the corresponding author upon reasonable request.

Effects of Leisure-Time Physical Activity on Cognitive Reserve Biomarkers and Leisure Motivation in the Pre-Diabetes Elderly

The purpose of this study was to investigate the change in cognitive reserve biomarkers of the pre-diabetic individual according to the types of leisure-time physical activity (aerobic or resistance physical activity). The research subjects (n = 184) who participated in the survey were pre-diabetic and diabetic patients who were visiting university hospitals and welfare centers. The intervention subjects (n = 36) who were elderly females with pre-diabetes volunteered to participate in the study by performing regular physical exercise (aerobic or resistance exercise). The study participants were 65 years of age or older with pre-diabetes defined by a glycated hemoglobin (HbA1c) level of (5.7−6.4)%. All research subjects performed motivation and stress questionnaire survey. All intervention subjects participated in leisure-time physical activity (LTPA) for 12 weeks. Body composition, HbA1c, and cognitive reserve biomarkers were measured at baseline, and at 6 and 12 weeks. LTPA motivation confirmed that the LTPA participants had a high level of motivation. Stress confirmed that the stress level of LTPA participants was low. Two-way within-factor ANOVA revealed significant group × time interaction for weight (p < 0.05), BMI (p < 0.01), % fat (p < 0.001), SBP (p < 0.05), HbA1c (p < 0.001), BDNF (p < 0.001), and Beta-Amyloid 1−42 (p < 0.001). In both physical activity groups, HbA1c (p < 0.001), NGF (p < 0.05), BDNF (p < 0.05), and Cathepsin B (p < 0.05) improved significantly at 12 weeks, compared to baseline and 6 weeks. In the resistance physical activity group, Beta-Amyloid 1−42 (p < 0.01) and Homocysteine (p < 0.05) significantly decreased at 12 weeks, compared to baseline and at 6 weeks. The LTPA showed high levels of integrated and identified regulation among leisure motive types, and the level of stress was found to be low. The LTPA is effective in reducing the HbA1c levels of the pre-diabetes elderly. In addition, the pre-diabetes elderly were found to have increased NGF, BDNF, and cathepsin B, and decreased Beta-Amyloid 1−42 and homocysteine. Regular leisure-time physical activity has a positive effect on cognitive reserve biomarkers through improving glycemic control by reducing weight and % fat in the pre-diabetes elderly.

Acute effect of breaking up prolonged sitting on cognition: a systematic review

OBJECTIVES

To review the current evidence on the acute effects of interrupting prolonged periods of sitting with intermittent physical activity (PA) on cognition in healthy populations.

DESIGN

This systematic review followed the Preferred Reporting Items for Systematic Reviews and Meta-Analysis guidelines.

METHODS

Studies were included if they investigated the acute effects of taking regular PA breaks from sitting on cognition in healthy populations without any cardiovascular disease, history of brain injury, or psychiatric or neurological disorder. Four electronic databases-PubMed, Scopus, MEDLINE and ProQuest-were searched for eligible studies on 20 September 2020. Study quality was assessed using the Physiotherapy Evidence Database scale.

RESULTS

Seven studies, involving 168 participants aged between 18 and 80 years, were eligible for inclusion in this review. Three of the seven studies found positive effects of interrupting sitting with either (a) 3 min of relatively high-intensity (6 km/hour) walking every 30 min on attention and inhibitory control in young adults; (b) hourly breaks with progressively longer duration (10-30 min) of very light-intensity cycling/walking on attention, working memory and cognitive flexibility in adults with obesity; or (c) an initial bout of continuous moderate-intensity exercise, followed by interruption of post-exercise sitting with 3 min breaks of light-intensity walking (3.2 km/hour) every 30 min, on working memory in older adults with overweight.

CONCLUSION

Given the limited evidence with mixed findings on this topic in the literature and the heterogeneity of PA protocols across the included studies, the results regarding the effectiveness of interrupting prolonged sitting with PA breaks in improving cognition warrant further verification.

PROSPERO REGISTRATION NUMBER

CRD42020147536.

Leg Fidgeting Improves Executive Function following Prolonged Sitting with a Typical Western Meal: A Randomized, Controlled Cross-Over Trial

Prolonged uninterrupted sitting and a typical Western meal, high in fat and refined sugar, can additively impair cognitive and cerebrovascular functions. However, it is unknown whether interrupting these behaviours, with a simple desk-based activity, can attenuate the impairment. The aim of this study was to determine whether regular leg fidgeting can off-set the detrimental effects of prolonged sitting following the consumption of a typical Western meal, on executive and cerebrovascular function. Using a randomized cross-over design, 13 healthy males consumed a Western meal and completed 180-min of prolonged sitting with leg fidgeting of 1 min on/4 min off (intervention [INT]) and without (control [CON]). Cognitive function was assessed pre and post sitting using the Trail Maker Test (TMT) parts A and B. Common carotid artery (CCA) blood flow, as an index of brain flow, was measured pre and post, and cerebral (FP1) perfusion was measured continuously. For TMT B the CON trial significantly increased (worsened) completion time (mean difference [MD] = 5.2 s, d = 0.38), the number of errors (MD = 3.33, d = 0.68) and cognitive fatigue (MD = 0.73, d = 0.92). Compared to CON, the INT trial significantly improved completion time (MD = 2.3 s, d = 0.97), and prevented declines in cognitive fatigue and a reduction in the number of errors. No significant changes in cerebral perfusion or CCA blood flow were found. Leg fidgeting for 1-min on/4-min off following a meal high in fats and refined sugars attenuated the impairment in executive function. This attenuation in executive function may not be caused by alterations in CCA blood flow or cerebral perfusion.

Sedentary behaviors and risk of depression in the Seguimiento Universidad de Navarra cohort: the SUN Project

The study aimed to prospectively examine the association between different sedentary behaviors and the risk of depression. We included 12,691 Spanish university graduates (mean age: 36.7 year; SD: 11.5), participants of the Seguimiento Universidad de Navarra cohort (the SUN Project), initially free of depression who were followed-up for a median of 10.9 years. Based on items presented in our baseline questionnaire, time spent in four sedentary behaviors (hours/day) were evaluated: overall sitting time; TV-viewing; computer use; and driving. Participants were classified as incident cases of depression if they reported a physician diagnosis of depression in at least one of the follow-up assessments conducted after the first two years of follow-up. Cox regression models were used to assess the relationship between sedentary behaviors and depression. A total of 560 incident cases of depression were identified during follow-up. We found no significant association between overall sitting time, TV-viewing or driving and risk of depression. On the other hand, computer use was directly associated with the risk of developing depression during the follow-up (p-value for trend = 0.020), with the participants in the highest quartile of computer use (3.64 to 10 hours/week) having a higher risk of developing depression (HR = 1.33; 95%CI: 1.05-1.70) than those in the lowest quartile (0 to 0.25 hours/week) after adjusting for potential confounders. Prolonged use of computer was independently associated with an increased risk of developing depression among young middle-aged adult university graduates from a Spanish cohort.

Active Aging and Public Health: Evidence, Implications, and Opportunities

By 2050, 20% of the world's population will be over the age of 65 years, with projections that 80% of older adults will be living in low- to middle-income countries. Physical inactivity and sedentary time are particularly high in older adults, presenting unique public health challenges. In this article, we first review evidence that points to multiple beneficial outcomes of active aging, including better physical function, cognitive function, mental health, social health, and sleep and suggest the need to shift the research focus from chronic disease outcomes to more relevant outcomes that affect independence and quality of life. Second, we review the critical role of age-friendly environments in facilitating active aging equitably across different countries and cultures. Finally, we consider emerging opportunities related to social engagement and technology-enabled mobility that can facilitate active aging. In all these contexts, it is a priority to understand and address diversity within the global aging population. Expected final online publication date for the Annual Review of Public Health, Volume 43 is April 2022. Please see http://www.annualreviews.org/page/journal/pubdates for revised estimates.