Differences in Habitual and Maximal Gait Velocity Across Age Groups: A Cross-Sectional Examination.

Prior work, primarily focusing on habitual gait velocity, has demonstrated a cost while walking when coupled with a cognitive task. The cost of dual-task walking is exacerbated with age and complexity of the cognitive or motor task. However, few studies have examined the dual-task cost associated with maximal gait velocity. Thus, this cross-sectional study examined age-related changes in dual-task (serial subtraction) walking at two velocities. Participants were classified by age: young-old (45-64 years), middle-old (65-79 years), and oldest-old (≥80 years). They completed single- and dual-task walking trials for each velocity: habitual (N = 217) and maximal (N = 194). While no significant Group × Condition interactions existed for habitual or maximal gait velocities, the main effects for both condition and age groups were significant (p < .01). Maximal dual-task cost (p = .01) was significantly greater in the oldest-old group. With age, both dual-task velocities decreased. Maximal dual-task cost was greatest for the oldest-old group.

Acute Citrulline-Malate Supplementation Increases Total Work in Short Lower-Body Isokinetic Tasks for Recreationally Active Females During Menstruation.

ABSTRACT: Gills, JL, Spliker, B, Glenn, JM, Szymanski, D, Romer, B, Lu, H-C, and Gray, M. Acute citrulline-malate supplementation increases total work in short lower-body isokinetic tasks for recreationally active females during menstruation. J Strength Cond Res 37(6): 1225-1230, 2023-Citrulline-malate (CM) exhibits acute ergogenic benefits through nitric oxide production (NO) and augmentation of vasodilatory properties. Nitric oxide is upregulated by estrogen and may influence CM's ergogenic efficacy in women. Therefore, the objective of this study was to evaluate the acute effects of CM supplementation on lower-body isokinetic performance in recreationally active women. Nineteen women (23.5 ± 3.1 years; 164.8 ± 7.0 cm; 61.9 ± 27.4 kg; 28.8 ± 8.1% body fat) completed 2 randomized, double-blind, crossover trials consuming CM (8 g CM + 12 g dextrose) or placebo (12 g dextrose). For testing trials, subjects were in the menstruating portion of the follicular phase of their menstrual cycle. Subjects performed a 5-repetition isokinetic leg extension protocol (5RP) followed by a 50-repetition isokinetic leg extension protocol (50RP), 60 minutes after supplement consumption. Repeated measures analysis of variance analysis showed that CM significantly increased total work completed, relative total work, and total work during maximum repetition compared with placebo ( p < 0.05); but no significant performance differences existed between trials for peak torque production ( p = 0.14) for the 5RP. No significant differences were identified between trials for peak torque production ( p = 0.69 ) or total work ( p = 0.33) completed during the 50RP. CM increased total work completed during the 5RP, but provided no ergogenic benefit during the 50RP in recreationally active menstruating women. CM amplifies power-based resistance exercise performance in women during the follicular phase of the menstrual cycle, potentially because of depressed estrogen levels. Additional research is needed to identify timing efficacy of CM to increase sport performance during each phase of the menstrual cycle.

Sit-to-Stand Power Across the Lifespan: A Cross-Sectional Analysis.

Lower-body power measured by a linear position transducer during the sit-to-stand (STS) movement declines with age and may be a predictor of physical disability in older adults. The purpose of this study was to establish normative data for STS power across the lifespan and to determine if differences exist between age cohorts, sexes, and age cohort-sex subgroups. Adults (N = 557) aged 18-89 were divided into five age cohorts and performed the STS connected to a linear position transducer, which calculated power and velocity during the movement. Significantly lower (p < .01) velocity was observed in a younger age cohort in females than males, whereas males saw a significant average power decrement (p < .01) in a younger age cohort than females. STS power norms give clinicians a metric predicting physical disability and may be of particular interest to males as their power production begins to decline at an earlier age.

Obstructive Sleep Apnea and Alzheimer's Disease Pathology: Is Sleep Architecture the Missing Key?

Impairments of the sleep architecture due to disrupted sleep in individuals with obstructive sleep apnea (OSA) may result in reduced slow wave sleep (SWS), intermittent hypoxemia, and excessive day time sleepiness- all factors that have been shown to impact Alzheimer's disease (AD) risk. In this commentary, we comment on the work by Cavuoto and colleagues in which they examine the associations between nocturnal hypoxemia or sleep disruptions (during SWS) and amyloid-ß burden in individuals with OSA. We review the findings in the context of other similar studies and highlight the strengths and weaknesses of these published studies. We note the importance of examining these relationships longitudinally with a large sample size, including considering sleep health disparities, vascular components, and multiple cognitive domain tests.

Hypertension is associated with reduced resting-state medial temporal lobe dynamic network flexibility in older African Americans.

Hypertension disproportionately affects African Americans and is a risk factor for Alzheimer's disease (AD). We investigated the relationship of blood pressure (BP) with medial temporal lobe (MTL) dynamic network flexibility (a novel AD biomarker) and cognitive generalization in older African Americans. In a cross-sectional study, 37 normotensive (systolic BP <130 mmHg, 82.5% F, 64.4 ± 4.9 years; 14.3 ± 2.1 years of education) versus 79 hypertensive (systolic BP ≥130 mmHg, 79.5% F, 66.8 ± 4.1 years; 14.0 ± 0.2 years of education) participants were enrolled. All participants completed a 10-min resting-state functional magnetic resonance imaging scan to assess MTL dynamic network flexibility and two generalization tasks to assess cognition. Anthropometrics and aerobic fitness (via 6-min walk test) were also determined. There was no difference in BMI (29.7 ± 6.4 vs. 31.9 ± 6.3 kg/m2, p = 0.083) or aerobic fitness (15.5 ± 2.6 vs. 15.1 ± 2.6 mL/kg/min; p = 0.445) between normotensive and hypertensive groups. However, normotensive participants had higher MTL dynamic network flexibility compared to hypertensive participants (0.42 ± 0.23 vs. 0.32 ± 0.25 mL, p = 0.040), and this was associated with higher mean arterial blood pressure (r = -0.21, p = 0.036). Therefore, hypertensive older African Americans demonstrated lower MTL dynamic network flexibility compared to their normotensive counterparts independent of BMI and aerobic fitness. Further studies are required to determine how blood pressure mediates AD risk in African Americans.

Obesity reduces hippocampal structure and function in older African Americans with the APOE-ε4 Alzheimer's disease risk allele.

Introduction: Excess body weight and Alzheimer's disease (AD) disproportionately affect older African Americans. While mid-life obesity increases risk for AD, few data exist on the relationship between late-life obesity and AD, or how obesity-based and genetic risk for AD interact. Although the APOE-ε4 allele confers a strong genetic risk for AD, it is unclear if late-life obesity poses a greater risk for APOE-ε4 carriers compared to non-carriers. Here we assessed: (1) the influence of body mass index (BMI) (normal; overweight; class 1 obese; ≥ class 2 obese) on cognitive and structural MRI measures of AD risk; and (2) the interaction between BMI and APOE-ε4 in older African Americans. Methods: Seventy cognitively normal older African American participants (Mage = 69.50 years; MBMI = 31.01 kg/m2; 39% APOE-ε4 allele carriers; 86% female) completed anthropometric measurements, physical assessments, saliva collection for APOE-ε4 genotyping, cognitive testing, health and lifestyle questionnaires, and structural neuroimaging [volume/surface area (SA) for medial temporal lobe subregions and hippocampal subfields]. Covariates included age, sex, education, literacy, depressive symptomology, and estimated aerobic fitness. Results: Using ANCOVAs, we observed that individuals who were overweight demonstrated better hippocampal cognitive function (generalization of learning: a sensitive marker of preclinical AD) than individuals with normal BMI, p = 0.016, ηp2 = 0.18. However, individuals in the obese categories who were APOE-ε4 non-carriers had larger hippocampal subfield cornu Ammonis region 1 (CA1) volumes, while those who were APOE-ε4 carriers had smaller CA1 volumes, p = 0.003, ηp2 = 0.23. Discussion: Thus, being overweight by BMI standards may preserve hippocampal function, but obesity reduces hippocampal structure and function in older African Americans with the APOE-ε4 Alzheimer's disease risk allele.

Examining the efficacy of a cardio-dance intervention on brain health and the moderating role of ABCA7 in older African Americans: a protocol for a randomized controlled trial.

Introduction: African Americans are two to three times more likely to be diagnosed with Alzheimer's disease (AD) compared to White Americans. Exercise is a lifestyle behavior associated with neuroprotection and decreased AD risk, although most African Americans, especially older adults, perform less than the recommended 150 min/week of moderate-to-vigorous intensity exercise. This article describes the protocol for a Phase III randomized controlled trial that will examine the effects of cardio-dance aerobic exercise on novel AD cognitive and neural markers of hippocampal-dependent function (Aims #1 and #2) and whether exercise-induced neuroprotective benefits may be modulated by an AD genetic risk factor, ABCA7 rs3764650 (Aim #3). We will also explore the effects of exercise on blood-based biomarkers for AD. Methods and analysis: This 6-month trial will include 280 African Americans (≥ 60 years), who will be randomly assigned to 3 days/week of either: (1) a moderate-to-vigorous cardio-dance fitness condition or (2) a low-intensity strength, flexibility, and balance condition for 60 min/session. Participants will complete health and behavioral surveys, neuropsychological testing, saliva and venipuncture, aerobic fitness, anthropometrics and resting-state structural and functional neuroimaging at study entry and 6 months. Discussion: Results from this investigation will inform future exercise trials and the development of prescribed interventions that aim to reduce the risk of AD in African Americans.

The effect of a digital health coaching and health education protocol on cognition in adults at-risk for Alzheimer's.

Several modifiable lifestyle factors have been linked to cognitive ability and the risk of developing Alzheimer's disease and related dementias (ADRD). Health coaching (HC) is an intervention that addresses lifestyle factors associated with cognition. The effectiveness of an HC protocol was evaluated and compared with a health education (HE) intervention, representing the current standard of care, in a sample of 216 adults between the ages of 45 and 75 years who were at-risk for developing ADRD. Outcomes examined were global cognition, neuropsychological cognition, and Alzheimer's risk. HC participants received personalized coaching from a health coach focusing on nutrition, physical activity, sleep, stress, social engagement, and cognitive activity. HE participants received biweekly education materials focusing on the same modifiable lifestyle factors addressed by HC. Participants were assessed at baseline and again 4 months later. Self-reported global cognition scores improved only in the HC group (16.18 to 15.52, p = .03) and neuropsychological cognitive ability improved in the HE group (104.48 to 108.76, p < .001). When non-adherence in the HC group was accounted for, however, the mean change in neuropsychological score was similar between groups (p > .05), self-reported global cognition demonstrated an even larger mean improvement in the HC group (16.20 to 15.41, p = .01), and the HC group saw an improvement in ADRD protective risk score (- 10.39 to - 11.45, p = .007). These results indicate that HC and HE can both improve cognition, but HC may be more effective and may yield increased protection against ADRD risk.

Intervention for a Digital, Cognitive, Multi-Domain Alzheimer Risk Velocity Study: Protocol for a Randomized Controlled Trial.

BACKGROUND: In the United States, more than 6 million adults live with Alzheimer disease (AD) that affects 1 out of every 3 older adults. Although there is no cure for AD currently, lifestyle-based interventions aimed at slowing the rate of cognitive decline or delaying the onset of AD have shown promising results. However, most studies primarily focus on older adults (>55 years) and use in-person interventions. OBJECTIVE: The aim of this study is to determine the effects of a 2-year digital lifestyle intervention on AD risk among at-risk middle-aged and older adults (45-75 years) compared with a health education control. METHODS: The lifestyle intervention consists of a digitally delivered, personalized health coaching program that directly targets the modifiable risk factors for AD. The primary outcome measure is AD risk as determined by the Australian National University-Alzheimer Disease Risk Index; secondary outcome measures are functional fitness, blood biomarkers (inflammation, glucose, cholesterol, and triglycerides), and cognitive function (Repeatable Battery for the Assessment of Neuropsychological Status and Neurotrack Cognitive Battery). Screening commenced in January 2021 and was completed in June 2021. RESULTS: Baseline characteristics indicate no difference between the intervention and control groups for AD risk (mean -1.68, SD 7.31; P=.90). CONCLUSIONS: The intervention in the Digital, Cognitive, Multi-domain Alzheimer Risk Velocity is uniquely designed to reduce the risk of AD through a web-based health coaching experience that addresses the modifiable lifestyle-based risk factors. TRIAL REGISTRATION: ClinicalTrials.gov NCT04559789; https://clinicaltrials.gov/show/NCT04559789. INTERNATIONAL REGISTERED REPORT IDENTIFIER (IRRID): DERR1-10.2196/31841.

Asynchronous Remote Assessment for Cognitive Impairment: Reliability Verification of the Neurotrack Cognitive Battery.

BACKGROUND: As evidenced by the further reduction in access to testing during the COVID-19 pandemic, there is an urgent, growing need for remote cognitive assessment for individuals with cognitive impairment. The Neurotrack Cognitive Battery (NCB), our response to this need, was evaluated for its temporal reliability and stability as part of ongoing validation testing. OBJECTIVE: The aim of this study is to assess the temporal reliability of the NCB tests (5 total) across a 1-week period and to determine the temporal stability of these measures across 3 consecutive administrations in a single day. METHODS: For test-retest reliability, a range of 29-66 cognitively healthy participants (ages 18-68 years) completed each cognitive assessment twice, 1 week apart. In a separate study, temporal stability was assessed using data collected from 31 different cognitively healthy participants at 3 consecutive timepoints in a single day. RESULTS: Correlations for the assessments were between 0.72 and 0.83, exceeding the standard acceptable threshold of 0.70 for temporal reliability. Intraclass correlations ranged from 0.60 to 0.84, indicating moderate to good temporal stability. CONCLUSIONS: These results highlight the NCB as a brief, easy-to-administer, and reliable assessment for remote cognitive testing. Additional validation research is underway to determine the full magnitude of the clinical utility of the NCB.

Acute citrulline-malate supplementation is ineffective during aerobic cycling and subsequent anaerobic performance in recreationally active males.

Citrulline-malate (CM) purportedly increases exercise performance through increased nitric oxide production. The effects of CM on muscular strength performance are well-documented; however, the benefits of CM on aerobic and anaerobic biking performance are not well researched. Therefore, the present investigation examined the acute CM supplementation effects on aerobic and anaerobic cycling performance in recreationally active males. Methods: 28 recreationally active males (20.9 ± 2.8 years) completed randomized, double-blind, crossover trials consuming CM (12g dextrose + 8g CM) or a placebo (12g dextrose). Participants performed an aerobic cycling protocol (time-to-exhaustion [TTE]), followed by a subsequent 30-second Wingate cycling test, 60-minutes after supplement consumption. Results: Dependent t-tests showed no significant differences (p > 0.05) for TTE (PLA: 315.4 s ± 137.7 s; CM: 314.1 s ± 107.1 s) and Total Work Completed (TWC) (PLA: 74.7 ± 34.1 kilojoules (kJ); CM: 74.1 ± 26.4 kJ) during the aerobic cycling protocol. Dependent t-tests also showed no significant differences (p > 0.05) for mean watts (PLA: 586.1 ± 87.7 Watts (W); CM: 588.0 ± 93.0 W), peak watts (PLA: 773.0 ± 136.7 W; CM: 786.7 ± 133.0 W), and fatigue index (PLA: 12.9 ± 6.4 FI; CM: 14.3 ± 7.2 FI) during the Wingate protocol. Repeated-measures ANOVA results indicated a significant effect between each 5 s interval (p < 0.001), but no differences were observed between trials (p > 0.05). Conclusion: Acute CM supplementation in recreationally active males provides no ergogenic benefit in aerobic cycling performance followed by an anaerobic cycling test.

A short digital eye-tracking assessment predicts cognitive status among adults.

Current cognitive assessments suffer from limited scalability and high user burden. This study aimed to (1) examine the relationship between a brief eye-tracking-based visual paired-comparison (VPC) and gold standard cognitive assessments, (2) examine longitudinal stability of the VPC task, (3) determine the ability of the VPC task to differentiate between cognitively normal (CN) individuals and individuals with mild cognitive impairment (MCI). Fifty-five adults (n = 44 CN, n = 11 MCI; 56.4 ± 26.7 years) were tested on two occasions, separated by at least 14 days. Visit 1 included VPC, Montreal Cognitive Assessment (MoCA), Digit Symbol Coding test (DSC), and NIH Toolbox Cognitive Battery (NIHTB-CB). Visit 2 included VPC, DSC, NIHTB-CB, and dual-task (DT). Significant differences existed between baseline VPC scores for CN and MCI groups (p < .001). VPC scores remained stable over time in both groups (p < .05). Significant associations existed between VPC and MoCA (p < .01), DSC (p < .001), and various NIHTB-CB subtests at both time points. The VPC test significantly predicts cognitive outcomes (p < .05), with age and VPC being the only significant predictors. Additionally, area under the curve (receiver operator characteristic = 0.80) for VPC scores demonstrated good classification accuracy. VPC reliably predicted cognitive status while remaining stable over time and displayed significant associations with gold standard cognitive assessments. VPC is a less burdensome and more scalable assessment than traditional tests, enabling longitudinal monitoring of cognitive status in resource-limited environments.

Acute Inositol-Stabilized Arginine Silicate Improves Cognitive Outcomes in Healthy Adults.

Inositol-stabilized arginine silicate (ASI) is an ergogenic aid that upregulates nitric oxide. Acute ASI supplementation improves working memory and processing speed in young adults but there is a lack of data examining other cognitive tasks. Therefore, the purpose of this study was to examine acute ASI effects on young healthy adults by assessing multiple cognitive domains. Nineteen young adults (20.9 ± 3.2 years) completed this randomized, double-blind, crossover study consuming ASI (1.5 g ASI + 12 g dextrose) and placebo (12 g dextrose). The participants completed the Repeatable Battery for the Assessment of Neuropsychological Status (RBANS) and two digital cognitive assessments before consuming the supplement and then completed the same battery of tests 60 min post-supplementation. Repeated measures ANOVA demonstrated that ASI consumption significantly improved total RBANS and immediate memory scores compared to the placebo (p < 0.05). However, no significant differences were displayed between trials for other cognitive domains (p > 0.05). Acute ASI ingestion increased overall RBANS scores and immediate memory scores in young adults. More research is needed to examine the acute effects of ASI on other domains of cognition, in older populations, and its long-term effects on cognition.

Cognitive decline negatively impacts physical function.

Many older adults report difficulty performing one or more activities of daily living. These difficulties may be attributed to cognitive decline and as a result, measuring cognitive status among aging adults may help provide an understanding of current functional status. The purpose of the present investigation was to determine the association between cognitive status and measures of physical functioning. Seventy-six older adults participated in this study; 41 were categorized as normal memory function (NM) and 35 were poor memory function (PM). NM participants had significantly higher physical function as measured by Short Physical Performance Battery (SPPB; 9.4 ± 2.2 vs. 8.4 ± 2.0; p = .03) and peak velocity (0.67 ± 0.16 vs. 0.56 ± 0.19; p = .04) during a quick sit-to-stand task. Dual-task walking velocities were 22% and 126% slower between cognitive groups for the fast and habitual trials, respectively when compared to the single-task walking condition. Significant correlations existed between measures of memory and physical function. The largest correlations with memory were for peak (r = 0.42) and average (r = 0.38) velocity. The results suggest a positive relationship between physical function and cognitive status. However, further research is needed to determine the mechanism of the underlying relationships between physical and cognitive function.

Validation of a digitally delivered visual paired comparison task: reliability and convergent validity with established cognitive tests.

Alzheimer's disease (AD) affects the memory and cognitive function of approximately 5.7 million Americans. Early detection subsequently allows for earlier treatment and improves outcomes. Currently, there exists a validated 30-min eye-tracking cognitive assessment (VPC-30) for predicting AD risk. However, a shorter assessment would improve user experience and improve scalability. Thus, the purposes were to (1) determine convergent validity between the 5-min web camera-based eye-tracking task (VPC-5) and VPC-30, (2) examine the relationship between VPC-5 and gold-standard cognitive tests, and (3) determine the reliability and stability of VPC-5. This prospective study included two healthy cohorts: older adults (65+ years, n = 20) and younger adults (18-46 years, n = 24). Participants were tested on two separate occasions. Visit 1 included the Montreal Cognitive Assessment (MoCA), Digit Symbol Coding test (DSC), NIH Toolbox Cognitive Battery (NIHTB-CB), VPC-30, and VPC-5. Visit 2 occurred at least 14 days later; participants completed the VPC-5, DSC, NIHTB-CB, and dual-task walking assessments (DT). VPC-30 significantly correlated with VPC-5 at the first (p < .001) and second (p = .001) time points. VPC-5 and DSC (p < .01) and Pattern Comparison Processing Speed Test (PSPAC) (p = .01) were also correlated on day 1. Significant associations existed between VPC-5 and DSC (p < .001), Flanker Inhibitory Control Test (p = .05), PSPAC (p < .001), and Picture Sequence Memory Test (p = .02) during day 14 testing session. The test retest reliability of VPC-5 was significant (p < .001). VPC-5 displayed moderate convergent validity with the VPC-30 and gold-standard measures of cognition, while demonstrating strong stability, suggesting it is a valuable assessment for monitoring memory function.

Face-to-Face and Digital Multidomain Lifestyle Interventions to Enhance Cognitive Reserve and Reduce Risk of Alzheimer's Disease and Related Dementias: A Review of Completed and Prospective Studies.

BACKGROUND: Currently, there is no pharmaceutical intervention to treat or delay pathological cognitive decline or Alzheimer's disease and related dementias (ADRD). Multidomain lifestyle interventions are increasingly being studied as a non-pharmacological solution to enhance cognitive reserve, maintain cognition, and reduce the risk of or delay ADRD. Review of completed and prospective face-to-face (FTF) and digital multidomain interventions provides an opportunity to compare studies and informs future interventions and study design. METHODS: Electronic databases (PubMed, PsycINFO, clinicaltrials.gov and NIH RePORTER) were searched for multidomain lifestyle programs. Studies were included if the program (1) included a control group, (2) included at least 3 interventions, (3) were at least 6 months in duration, and (4) included measurement of cognitive performance as an outcome. RESULTS: In total, 17 multidomain lifestyle programs aimed at enhancing cognitive reserve and reducing risk of ADRD were found. Thirteen programs are FTF in intervention delivery, with 3 FTF programs replicating the FINGER protocol as part of the World Wide Fingers Consortium. Four programs are delivered digitally (website, Web application, or mobile app). Program characteristics (e.g., target population, duration, frequency, outcomes, and availability) and results of completed and prospective studies are reviewed and discussed. CONCLUSION: This review updates and discusses completed and current multidomain lifestyle interventions aimed at enhancing cognitive reserve and reducing risk of ADRD. A growing number of international studies are investigating the efficacy and utility of these programs in both FTF and digital contexts. While a diversity of study designs and interventions exist, FTF and digital programs that build upon the foundational work of the FINGER protocol have significant potential to enhance cognitive reserve and reduce risk of ADRD.