The mediating role of lower body muscle strength and IGF-1 level in the relationship between age and cognition. A MIDUS substudy.

OBJECTIVE: Aging is a natural process associated with a decline in cognition. However, the mediating effect of physical function and circulating myokines on this relationship has yet to be fully clarified. This study investigated how muscle strength and circulating insulin-like growth factor-1 (IGF-1) levels mediate the relationship between age and cognitive functions. SUBJECTS AND METHODS: A total of 1255 participants aged 25-74 years included in the Midlife in the United States II study were retrospectively analyzed. In this cross-sectional analysis, we applied a serial mediation model to explore the mediating effects of muscle strength and circulating IGF-1 levels on the relationship between age and cognitive functions. We included potential confounding factors related to sociodemographics, lifestyle, and health status as covariates in the model. RESULTS: The results showed that aging had both direct and indirect effects on cognition. As predicted, muscle strength and IGF-1 levels mediated the relationship between age and specific cognitive functions. In addition, mediation analyses indicated that the association between aging and cognitive flexibility, immediate and delayed memory, and inductive reasoning were partially mediated by muscle strength and IGF-1 levels in a serial manner. CONCLUSIONS: Our study demonstrated the serial multiple mediation roles of muscle strength and IGF-1 levels on the relationship between age and specific cognitive functions. Further longitudinal research should be performed to confirm the serial mediation results.

Multiple routes to help you roam: A comparison of training interventions to improve cognitive-motor dual-tasking in healthy older adults.

Cognitive-motor dual-tasking is a complex activity that predicts falls risk and cognitive impairment in older adults. Cognitive and physical training can both lead to improvements in dual-tasking; however, less is known about what mechanisms underlie these changes. To investigate this, 33 healthy older adults were randomized to one of three training arms: Executive function (EF; n = 10), Aerobic Exercise (AE; n = 10), Gross Motor Abilities (GMA; n = 13) over 12 weeks (1 h, 3×/week). Single and dual-task performance (gait speed, m/s; cognitive accuracy, %) was evaluated before and after training, using the 2-back as concurrent cognitive load. Training arms were designed to improve cognitive and motor functioning, through different mechanisms (i.e., executive functioning - EF, cardiorespiratory fitness - CRF, and energy cost of walking - ECW). Compared to baseline, we observed few changes in dual-task gait speed following training (small effect). However, dual-task cognitive accuracy improved significantly, becoming facilitated by walking (large effect). There were no differences in the magnitude of improvements across training arms. We also found that older adults with lower cognitive ability (i.e., MoCA score < 26; n = 14) improved more on the dual-task cognitive accuracy following training, compared to older adults with higher cognitive ability (i.e., MoCA ≥26; n = 18). Taken together, the results suggest that regardless of the type of intervention, training appears to strengthen cognitive efficiency during dual-tasking, particularly for older adults with lower baseline cognitive status. These gains appear to occur via different mechanisms depending on the form of intervention. Implications of this research are paramount, as we demonstrate multiple routes for improving cognitive-motor dual-tasking in older adults, which may help reduce risk of cognitive impairment.

Bridging the Gap between Research and the Community: Implementing Physical and Cognitive Interventions to Improve Spontaneous Walking Speed in Older Adults.

The application of interventions to enhance mobility in ecological settings remain understudied. This study was developed to evaluate the feasibility of training methods in a community centre and to evaluate their impact on mobility outcomes. Fifty-four participants were randomized to one of three 12-week training programs (three times/week): aerobic (AE), gross motor abilities (GMA) or cognitive (COG). Feasibility was evaluated by calculating adherence, feedback from participants and long-term participation. The impact of these interventions on mobility was assessed by comparing pre- and post-program on Timed-up-and-go (TUG) and spontaneous walking speed (SWS) performances. Results showed relatively high rates of adherence (85.1%) and long-term participation (66.7%), along with favorable feedbacks. SWS significantly improved in COG (0.10 ± 0.11 m.s-1; p = 0.004) and AE (0.06 ± 0.11 m.s-1; p = 0.017) groups, and TUG performance was maintained in all groups. Results of this feasibility study demonstrated successful implementation of physical and cognitive training programs, encouraging the development of real-world applications.

A Comparison of the Effect of Physical Activity and Cognitive Training on Dual-Task Performance in Older Adults.

OBJECTIVES: Studies suggest that cognitive training and physical activity can improve age-related deficits in dual-task performances. However, both of these interventions have never been compared in the same study. This article investigates the improvement in dual-task performance in 2 types of exercise training groups and a cognitive training group and explores if there are specific dual-task components that are more sensitive or more likely to improve following each type of training. METHODS: Seventy-eight healthy inactive participants older than the age of 60 (M = 69.98, SD = 5.56) were randomized to one of three 12-week training programs: aerobic training (AET) = 26, gross motor abilities (GMA) = 27, and cognition (COG) = 25. Before and after the training program, the participants underwent physical fitness tests, and cognitive evaluations involving a computerized cognitive dual task. The AET consisted of high- and low-intensity aerobic training, the GMA of full-body exercises focusing on agility, balance, coordination, and stretching, and the COG of tablet-based exercises focusing on executive functions. RESULTS: Repeated-measures analysis of variance on reaction time data revealed a group × time interaction (F(2,75) = 11.91, p < .01) with COG having the greatest improvement, followed by a significant improvement in the GMA group. Secondary analysis revealed the COG to also improve the intraindividual variability in reaction time (F(1,24) = 8.62, p < .01), while the GMA improved the dual-task cost (F(1,26) = 12.74, p < .01). DISCUSSION: The results show that physical and cognitive training can help enhance dual-task performance by improving different aspects of the task, suggesting that different mechanisms are in play.

Comparing the effect of cognitive vs. exercise training on brain MRI outcomes in healthy older adults: A systematic review.

Aging is associated with cognitive decline. Importantly cognition and cerebral health is enhanced with interventions like cognitive (CT) and exercise training (ET). However, effects of CT and ET interventions on brain magnetic resonance imaging outcomes have never been compared systematically. Here, the primary objective was to critically and systematically compare CT to ET in healthy older adults on brain MRI outcomes. A total of 38 studies were included in the final review. Although results were mixed, patterns were identified: CT showed improvements in white matter microstructure, while ET demonstrated macrostructural enhancements, and both demonstrated changes to task-based BOLD signal changes. Importantly, beneficial effects for cognitive and cerebral outcomes were observed by almost all, regardless of intervention type. Overall, it is suggested that future work include more than one MRI outcome, and report all results including null. To better understand the MRI changes associated with CT or ET, more studies explicitly comparing interventions within the same domain (i.e. resistance vs. aerobic) and between domains (i.e. CT vs. ET) are needed.

A comparison of physical exercise and cognitive training interventions to improve determinants of functional mobility in healthy older adults.

OBJECTIVES: Mobility is a complex but crucial clinical outcome in older adults. Past observational studies have highlighted that cardiorespiratory fitness (CRF), energy cost of walking (ECW), and cognitive switching abilities are associated with mobility performance, making these key determinants of mobility intervention targets to enhance mobility in older adults. The objective of this study was to compare, in the same design, the impact of three training methods - each known to improve either CRF, ECW, or cognitive switching abilities - on mobility in healthy older adults. METHODS: Seventy-eight participants (69.28 ± 4.85yo) were randomly assigned to one of three twelve-week interventions: Aerobic Exercise (AE; n = 26), Gross Motor Abilities (GMA; n = 27), or Cognitive (COG; n = 25) training. Each intervention was designed to improve one of the three key determinants of mobility (CRF, ECW, and cognitive switching). Primary outcomes (usual gait speed, and TUG performance) and the three mobility determinants were measured before and after the intervention. RESULTS: Repeated-measures ANOVAs showed a time effect for TUG performance (F(1,75) = 14.92, p < .001): all groups equally improved after the intervention (ΔTUGpost-pre, in seconds, with 95% CI: AE = -0.44 [-0.81 to -0.08]; GMA = -0.60 [-1.10 to -0.10]; COG = -0.33 [-0.71 to 0.05]). No significant between group differences were observed. CRF was improved in the AE group only (Hedges' G = 0.27, small effect), ECW and cognitive switching improved the most in the GMA (Hedges' G = -0.78, moderate effect) and COG groups (Hedges' G = -1.93, large effect) respectively. Smaller improvements in ECW were observed following AE and COG trainings (Hedges' G: AE = -0.39, COG = -0.36, both small effects) as well as in cognitive switching following AE and GMA training (Hedges' G: AE = -0.42, GMA = -0.21, both small effects). DISCUSSION: This study provides further support to the notion that multiple interventional approaches (aerobic, gross motor exercise, or cognitive training) can be employed to improve functional mobility in older adults, giving them, and professionals, more options to promote healthy ageing.

Physical Exercise Training Effect and Mediation Through Cardiorespiratory Fitness on Dual-Task Performances Differ in Younger-Old and Older-Old Adults.

OBJECTIVE: It has often been reported that dual-task (DT) performance declines with age. Physical exercise can help improve cognition, but these improvements could depend on cognitive functions and age groups. Moreover, the mechanisms supporting this enhancement are not fully elucidated. This study investigated the impacts of physical exercise on single- and dual-task performance in younger-old (<70) and older-old (70+) adults. The study also assessed whether the training effect on cognition was mediated by improvement in cardiorespiratory fitness. METHODS: One hundred forty-three participants (65-89 years) took part in a physical exercise intervention for 3 months or were assigned to a control group. All participants completed a DT paradigm and an estimated measure of cardiorespiratory fitness. Regression models were used to test the training effect on these outcomes, and mediation analyses were used to determine whether the training-related cognitive changes were mediated by changes in cardiorespiratory fitness. RESULTS: In 70+, training predicted improved processing speed (ßc = -.33) and cardiorespiratory fitness (ßa = .26) and the effect of training on processing speed was fully mediated by change in cardiorespiratory fitness (ßab = -.12). In <70, training predicted improvement in task-set cost (ßc = -.26) and change in cardiorespiratory fitness (ßa = .30) but improvement in task-set cost was not entirely mediated by change in cardiorespiratory fitness. DISCUSSION: Results are discussed in terms of the mechanisms supporting DT performance improvement following physical exercise training in older adults.

Normative Data for a Tablet-Based Dual-Task Assessment in Healthy Older Adults.

OBJECTIVE: The objective of this study is to provide normative data for a tablet-based dual-task assessment in older adults without cognitive deficits. METHOD: In total, 264 participants aged between 60 and 90 years, French and English-speaking, were asked to perform two discrimination tasks, alone and concurrently. The participants had to answer as fast as possible to one or two images appearing in the center of the tablet by pressing to the corresponding buttons. Normative data are provided for reaction time (RT), coefficient of variation, and accuracy. Analyses of variance were performed by trial types (single-pure, single-mixed, dual-mixed), and linear regressions assessed the relationship between performance and sociodemographic characteristics. RESULTS: The participants were highly educated and a large proportion of them were women (73.9%). The accuracy on the task was very high across all blocks. RT data revealed both a task-set cost and a dual-task cost between the blocks. Age was associated with slower RT and with higher coefficient of variability. Men were significantly slower on dual-mixed trials, but their coefficient of variability was lower on single-pure trials. Education was not associated with performance. CONCLUSIONS: This study provides normative data for a tablet-based dual-task assessment in older adults without cognitive impairment, which was lacking. All participants completed the task with good accuracy in less than 15 minutes and thus, the task is transferable to clinical and research settings.

Mind the Rhythm: ECG QT Dispersion and Cognition in Healthy Older Adults.

BACKGROUND: Autonomic function has been linked to cognitive abilities in aging. Even in non-clinical states, a certain variability in heart rhythm regulation can be measured with QT dispersion (QTcD), an ECG marker of ventricular repolarization which has been linked to autonomic function and cardiovascular health. QTcD has been shown to be higher in individuals with mild cognitive impairment, and the highest in individuals with Alzheimer's disease. The goal of this study was to see if QTcD is associated with cognitive performance in healthy individuals. METHODS: Sixty-three healthy inactive older adults (> 60 years) completed an extensive cognitive assessment (including inhibition, divided attention, updating, working memory, and processing speed), a physical fitness assessment, and underwent a resting ECG. RESULTS: After controlling for age, sex, and education, QTcD significantly predicted global cognition (MoCA) scores (R 2 = 0.17, F ( 4 . 58 ) = 3.00, p < 0.03, ß = -0.36). Exploratory analysis on the MoCA subcomponents revealed a significant association between the visual/executive subcomponent and QTcD (R 2 = 0.12, F (1 .6 1) = 7.99, p < 0.01, ß = -0.34). In individuals with high QTcD, QTcD values were linked to executive functions (R 2 = 0.37), processing speed (R 2 = 0.34), and dual-task performances (R 2 = 0.47). No significant associations were found within the low QTcD group. CONCLUSION: This study shows an association between ventricular repolarization (QTcD) and cognitive performance, in particular speed and executive functions, in healthy older adults. The results provide further support for linking autonomic heart regulation and age-related cognitive changes, and suggest that deviations on ECG, even within-normal range, could help detect early cognitive deficits.

Sex-moderated association between body composition and cognition in older adults.

BACKGROUND: Some studies have reported an association between body composition and cognition in older adults, but underlying mechanisms and physiological factors remain poorly understood. Moreover, sex-related differences in metabolic health and age-related cognitive decline have gained major interest lately. The present study investigated the potential moderating effect of sex on the relationship between body composition and cognition in older adults. METHODS: Global cognition, assessed by the Montreal Cognitive Assessment (MoCA), and body composition, measured using dual-energy x-ray absorptiometry (DXA), were analyzed in 155 women and 65 men aged 60 years old or more. Moderation analyses were computed to determine if sex moderates the effect of the different body composition parameters on the MoCA while controlling for the body mass index and the level of education of the participants. RESULTS: Sex moderated the association between total lean mass, trunk lean mass, arms lean mass, and the MoCA score. These body composition parameters were positively associated with cognition only in men. Fat mass was not associated with cognition in any sex. CONCLUSION: Overall, higher lean mass and in particular trunk and arms lean mass was associated with higher cognitive abilities in older men. Longitudinal studies or intervention studies are needed to further identify physiological mechanisms that sustain the relationship between lean mass and cognition.

Effects of an 8-week training cessation period on cognition and functional capacity in older adults.

BACKGROUND: Multiple types of exercise interventions have been described as effective methods for improving cognition and mobility in older adults. In addition to combined strength and aerobic training, gross motor activities have shown benefits. However, adherence to exercise is a challenge, which may bring about periods of training cessation. Importantly, short-term training cessation may lead to a loss of fitness adaptations. The effects of training cessation on cognition and functional capacity are not well known, especially within the context of dual-tasking in older adults. OBJECTIVES: We examined the effects of an 8-week training cessation period on cognition (executive functioning (EF) in single (ST) and dual-task (DT)) and functional capacity (10 m Walk and 6 Minute Walk Test) of healthy older adults, after one of three training interventions: combined lower body strength and aerobic, combined upper body strength and aerobic, or gross motor activities. MATERIALS AND METHODS: Forty older adults (70.5 ± 5.5 years, 67.5% F) participated in training sessions, 3×/week for 8 weeks prior to training cessation. Pre (T0), post (T1) and follow-up (post-cessation, T2) measures of EF (performance in inhibition and updating/working memory indices of the Random Number Generation task) in ST and DT (treadmill walking at 0.67 m·s-1, 1.11 m·s-1, and 1.56 m·s-1), and functional capacity were assessed. Changes in ST and DT as well as functional capacity tests were analyzed using two-way ANOVAs (time ∗ group) with repeated measures for the time factor (T0, T1 and T2). RESULTS: Improvements in inhibition indices were observed in ST for all time comparisons (T0-T1, T1-T2 and T0-T2). Inhibition in DT improved from T0-T2 and from T1-T2. Working memory declined from T0-T2 and from T1-T2. Functional capacity performance was maintained from T1-T2 (small improvement from T0-T1 and from T0-T2). DISCUSSION: Performances in inhibition were maintained or improved after cessation of training. We found no interaction between training groups, whatever the condition, indicating similar training cessation effects regardless of the intervention. CONCLUSIONS: Multiple types of exercise interventions may lead to positive benefit to inhibition and functional capacity in older adults, and it may also be possible to retain these benefits after a short cessation period.

Effects of Dance/Movement Training vs. Aerobic Exercise Training on cognition, physical fitness and quality of life in older adults: A randomized controlled trial.

INTRODUCTION: It is generally accepted that physical activity promotes healthy aging. Recent studies suggest dance could also benefit cognition and physical health in seniors, but many styles and approaches of dance exist and rigorous designs for intervention studies are still scarce. The aim of this study was to compare the effects of Dance/Movement Training (DMT) to Aerobic Exercise Training (AET) on cognition, physical fitness and health-related quality of life in healthy inactive elderly. METHODS: A single-center, randomized, parallel assignment, open label trial was conducted with 62 older adults (mean age = 67.48 ±â€¯5.37 years) recruited from the community. Participants were randomly assigned to a 12-week (3x/week, 1hr/session) DMT program, AET program or control group. Cognitive functioning, physical fitness and health-related quality of life were assessed at baseline (T-0), and post-training (T-12 weeks). RESULTS: 41 participants completed the study. Executive and non-executive composite scores showed a significant increase post-training (F(1,37) = 4.35, p = .04; F(1,37) = 7.01, p = .01). Cardiovascular fitness improvements were specific to the AET group (F(2,38) = 16.40, p < .001) while mobility improvements were not group-dependent (10 m walk: F(1,38) = 11.67, p = .002; Timed up and go: F(1,38) = 22.07, p < .001). CONCLUSIONS: Results suggest that DMT may have a positive impact on cognition and physical functioning in older adults however further research is needed. This study could serve as a model for designing future RCTs with dance-related interventions. REGISTRATION: clinicaltrials. gov Identifier NCT02455258.

Dance your stress away: comparing the effect of dance/movement training to aerobic exercise training on the cortisol awakening response in healthy older adults.

This study aimed to examine in healthy older adults the effects of dance/movement training (DMT) on the cortisol awakening response (CAR), a marker of chronic stress. Forty participants (mean age = 67.45, 75% women) were randomized into three groups: DMT (n = 12) - a set of exercises to promote gross motor skills, body awareness, and socialization; aerobic exercise training (AT; n = 14) - high intensity activity on a recumbent bicycle, and wait list (WL; n = 14). Both DMT and AT groups were supervised by licensed instructors and met three times a week for three months. Before and after their respective program, participants of all groups provided saliva samples on 3 d at 0-, 30- and 60-min after awakening, and had their fitness level evaluated. A significant group × time interaction (F(2,34) = 5.79, p = .01, η2partial = 0.25) was found, with the DMT group showing lower salivary cortisol values post-training, while the other two groups showed no change from baseline in their CAR. Cardiorespiratory fitness improved only in the AT group, while DMT showed no group-specific physical functioning improvements. The results are discussed in terms of the importance of physical and psychological effects of training on change in cortisol levels.

Trait Perceived Injustice Is Associated With Pain Intensity and Pain Behavior in Participants Undergoing an Experimental Pain Induction Procedure.

Recent research has revealed robust cross-sectional and prospective associations among perceived injustice, pain, disability, and depressive symptoms in patients with chronic pain. To date, research has proceeded from the assumption that perceived injustice arises as a consequence of debilitating injury or illness. However, it is possible that perceived injustice might have trait-like characteristics, persisting even in the absence of an injustice-related eliciting event. The aim of the present study was to develop and test a measure of trait perceived injustice (Trait Injustice Experience Questionnaire [T-IEQ]). The item content of the T-IEQ was drawn from the original IEQ and adapted for relevance to a noninjury context. A sample of 118 healthy undergraduates completed the T-IEQ, measures of just world belief, and trait forgiveness prior to participating in an experimental pain procedure. Pain intensity, pain behavior, and emotional responses were recorded during the painful induction. The T-IEQ had good internal consistency and test-retest reliability. The validity of the T-IEQ was supported by significant associations with measures of just world belief and trait forgiveness. The T-IEQ was also associated with pain intensity, pain behavior, and ratings of sadness and anger. Anger mediated the relation between the T-IEQ and pain outcomes. The results of the present study suggest that individuals vary in their trait-like propensity to experience negative life events as unjust and that trait perceived injustice contributes to adverse pain outcomes. PERSPECTIVE: The present findings suggest that perceived injustice might reflect an enduring tendency to experience negative life events as unjust. The findings also suggest that trait perceived injustice is associated with higher ratings of pain intensity and anger and more pronounced displays of pain behavior.

Disgust stimuli reduce heart rate but do not contribute to vasovagal symptoms.

BACKGROUND AND OBJECTIVES: The vasovagal response demonstrates a unique form of stress response, common in medical settings yet provoked by a variety of blood-injury-injection stimuli. This study aimed to better understand the psychophysiological mechanisms of the vasovagal response.. METHODS: 16 undergraduates with and 42 without a self-reported history of fainting watched five 3-5 min videos with different emotional content. One documentary clip (Neutral condition) described a campus environmental project while another (Blood/Injury) depicted portions of an open heart surgery. Three additional clips were also used, including Medical, Threat, and Contamination stimuli. Vasovagal symptoms and physiological variables were assessed during each video. RESULTS: As predicted, while the disgust-related stimuli (Blood/Injury, Medical, Contamination) were associated with generally lower heart rate, the Blood/Injury video produced the highest symptoms and the only significant difference between previous fainters and non-fainters. The physiological measures also revealed that participants with a fainting history experienced higher stroke volume and lower systolic blood pressure throughout, as well as several main effects of video. LIMITATIONS: An additional decrease in systolic blood pressure and respiration produced by watching the Blood/Injury video may have been sufficient to trigger symptoms in some, though results also suggest that systemic variables do not entirely explain susceptibility to symptoms. More careful evaluation of regional blood flow may be required. CONCLUSIONS: Participants who had previously experienced strong vasovagal responses displayed what appeared to be an anticipatory response to the Blood/Injury video. Finally, disgust stimuli may reduce heart rate but do not appear to contribute to vasovagal symptoms.