Healthy Adults Age Research Articles

Neuromodulatory effects of parietal high-definition transcranial direct-current stimulation on network-level activity serving fluid intelligence.

Fluid intelligence (Gf) involves rational thinking skills and requires the integration of information from different cortical regions to resolve novel complex problems. The effects of non-invasive brain stimulation on Gf have been studied in attempts to improve Gf, but such studies are rare and the few existing have reached conflicting conclusions. The parieto-frontal integration theory of intelligence (P-FIT) postulates that the parietal and frontal lobes play a critical role in Gf. To investigate the suggested role of parietal cortices, we applied high-definition transcranial direct current stimulation (HD-tDCS) to the left and right parietal cortices of 39 healthy adults (age 19-33years) for 20min in three separate sessions (left active, right active and sham). After completing the stimulation session, the participants completed a logical reasoning task based on Raven's Progressive Matrices during magnetoencephalography. Significant neural responses at the sensor level across all stimulation conditions were imaged using a beamformer. Whole-brain, spectrally constrained functional connectivity was then computed to examine the network-level activity. Behaviourally, we found that participants were significantly more accurate following left compared to right parietal stimulation. Regarding neural findings, we found significant HD-tDCS montage-related effects in brain networks thought to be critical for P-FIT, including parieto-occipital, fronto-occipital, fronto-parietal and occipito-cerebellar connectivity during task performance. In conclusion, our findings showed that left parietal stimulation improved abstract reasoning abilities relative to right parietal stimulation and support both P-FIT and the neural efficiency hypothesis. KEY POINTS: Abstract reasoning is a critical component of fluid intelligence and is known to be served by multispectral oscillatory activity in the fronto-parietal cortices. Recent studies have aimed to improve abstract reasoning abilities and fluid intelligence overall through behavioural training, but the results have been mixed. High-definition transcranial direct-current stimulation (HD-tDCS) applied to the parietal cortices modulated task performance and neural oscillations during abstract reasoning. Left parietal stimulation resulted in increased accuracy and decreased functional connectivity between occipital regions and frontal, parietal, and cerebellar regions. Future studies should investigate whether HD-tDCS alters abstract reasoning abilities in those who exhibit declines in performance, such as healthy ageing populations.

The effects of prolonged sitting with a mild hypercapnic environment on vascular function in elderly adults: A pilot study

Introduction: Prolonged Sitting (PS), defined a sitting for 2+ hours at a time, has been identified as an independent risk factor for cardiovascular disease (CVD). We previously reported that an acute bout of PS can attenuate macrovascular function in healthy young adults. Additionally, we reported that PS in mild hypercapnic environments (elevated CO2 concentrations) can further exacerbate these impairments in healthy young adults, and these impairments can be partially prevented by intermittent bouts of passive and active leg movements. However, the effects of prolonged sitting with a mild hypercapnic environment in the elderly population have not been studied. Therefore, the purpose of this study was to examine the impact of prolonged sitting with a mild hypercapnic condition on macrovascular function, arterial stiffness, and leg muscle metabolism. Additionally, we have further examined the effects of passive and active movements to negate the negative effects of prolonged sitting in elderly adults. Hypothesis: We hypothesized that 1) prolonged sitting in a hypercapnic environment will attenuate vascular function and leg metabolism, 2) both passive and active leg movements will preserve endothelial function and leg metabolism. Methods: Healthy elderly adults (n=2, 2 males, 69 ± 2.83 yrs) participated in three experimental visits consisting of 2.5h of prolonged sitting in a mild hypercapnic condition (CO2 = 1500ppm): control (CON), passive (PASS, passive leg movement), and active (ACT, active leg movement). Popliteal and brachial artery endothelial function was measured using flow-mediated dilation (FMD). Peripheral and central arterial stiffness was assessed using pulse wave velocity. Leg muscle metabolism was assessed using near infrared spectroscopy and a thermal camera. All measurements were taken pre- and post-siting. Results: Popliteal FMD was reduced in the CON condition compared to both the PASS and ACT (Δ -3.559 ± 0.499 vs Δ -1.799 ± 0.824 vs Δ 0.601 ± 1.958, respectively). Brachial FMD was attenuated in the CON condition compared to both compared to both the PASS and ACT (Δ -2.368 ± 0.215 vs Δ -0.285 ± 1.578 vs Δ 1.116 ± 1.174, respectively). The CON condition showed a greater reduction in leg temperature compared to both the PASS and ACT (Δ -2.4 vs Δ -1.6 ± 0.599 vs Δ 0.1 ± 0.224, respectively). No changes in central or peripheral arterial stiffness were observed. Conclusion: This preliminary data shows that uninterrupted prolonged sitting induces impairments in both local and systemic vascular function, leg muscle metabolism, but not arterial stiffness. Additionally, intermittent bouts of passive and active movements can partially preserve leg vascular function and metabolism during PS. This research was supported by the UNO Graduate Research and Creative Activity Grant, National Institutes of Health (RO1HD106911) and the Great Plains IdeaA-CTR (U54 GM115448). This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Does acute melatonin supplementation affect cerebrovascular reactivity in healthy young adults?

Melatonin receptors have been found in the cerebrovasculature in animal models, and melatonin has been shown to improve systemic vascular control. While there is a correlation between low melatonin production and cardiovascular disease, the effect of acute melatonin supplementation on the cerebrovasculature, and more specifically, cerebrovascular reactivity (CVR), is unknown. PURPOSE: To determine if acute melatonin supplementation alters CVR via CO2 rebreathing in healthy, young adults. Methods: 14 healthy young adults (Age 23.7±4.39, 7 females tested during the first 5 days of their menstrual cycle) participated in a familiarization visit followed by 2 experimental visits separated by ≥48hrs. Participants received a sublingual dose of either a placebo (PLA, mixture of mint extract and filtered water, to mimic taste of melatonin) or 5mg of melatonin (MEL, mint flavor) in a single-blind, randomized, crossover design. After ingestion, participants rested for 30 minutes prior to the experiment to allow for melatonin levels to reach peak concentration in the blood (Bartoli et al., 2013). After which, mean arterial pressure (MAP, mmHg, finger photoplethysmography), middle cerebral artery velocity (MCAv, cm/s, Transcranial Doppler), and end-tidal CO2 concentration (PetCO2, mmHg, Gas Analyzer) were measured continuously for 5 minutes of supine rest while breathing atmospheric air followed by a CO2 rebreathing challenge (CO2=3%, O2=40%, balanced N2) until the participant displayed a PetCO2 increase of ≥10mmHg. Cerebrovascular conductance index was calculated as CVCi = MCAv/MAP (cm/s/mmHg). CVR was calculated in absolute ΔMCAv/ΔPetCO2, ΔCVCi/ΔPetCO2, and percent change from resting values. Results: Data presented as change (Δ) from rest to CO2 rebreathing, as mean ± SD. All values were not different between treatments during rest. No value was significantly different between treatments when comparing Δ from rest to CO2 rebreathing (MCAv PLA Δ13.35±5.1 vs. MEL Δ11.62±6.03, p = 0.31, d = 0.28, MAP PLA Δ1.75±3.91 vs. MEL Δ-0.55±4.49, p = 0.20, d = 0.34, CVCi PLA Δ0.11±0.04 vs. MEL Δ0.11±0.05, p = 0.55, r = 0.16, CVRMCAv PLA Δ2.75±1.30 vs. MEL Δ3.54±2.57, p = 0.92, r = 0.03, %CVRMCAv PLA Δ18.41±7.07 vs. MEL Δ16.12±10.00, p = 0.36, r = 0.24, CVRCVCi PLA Δ0.02±0.03 vs. MEL Δ0.02±0.02, d = 0.28, p = 0.31, %CVRCVCi PLA Δ2.32±2.58 vs. MEL Δ1.52±1.83, d = 0.28, p = 0.31). CONCLUSION: Our results indicate that melatonin does not affect MCAv, CVCi, MAP, or CVR during rest or CO2 rebreathing. Reactivity was variable individually and did not trend in any direction when comparing PLA treatment to MEL treatment. Thus, melatonin supplementation does not improve cerebrovascular function indicating melatonin supplementation may have differential responses between the cerebral and peripheral vasculature in humans. This work was supported by a Robberson Research Grant provided by the University of Oklahoma graduate college. This is the full abstract presented at the American Physiology Summit 2024 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.

Effects of transcranial alternating current stimulation to the supplementary motor area on motor learning.

Transcranial alternating current stimulation (tACS) is a noninvasive method for brain stimulation that artificially modulates oscillatory brain activity in the cortical region directly beneath the electrodes by applying a weak alternating current. Beta (β) oscillatory activity in the supplementary motor area (SMA) is involved in motor planning and maintenance, whereas gamma (γ) oscillatory activity is involved in the updating of motor plans. However, the effect of applying tACS to the SMA on motor learning has not yet been investigated. This study assessed the effects of applying tACS to the SMA on motor learning. Forty-two right-handed healthy adults (age 20.6 ± 0.5 years, 24 men and 18 women) were included. Motor learning was assessed using a visuomotor tracking task with pinch tension of the right thumb and right forefinger. Each trial lasted 60 s, and the error rates were measured. Conductive rubber electrodes were attached to the SMA and the left shoulder for tACS. Stimulation was applied at an intensity of 1.0 mA and frequencies of 70 and 20 Hz in the γ-tACS and β-tACS treatment groups, respectively. The sham group was only administered a fade-in/out. The visuomotor tracking task was performed for 10 trials before tACS and 10 trials after tACS. Two trials were conducted on the following day to determine motor skill retention. The average deviation measured during 60 s was considered the error value. Pre-stimulation learning rate was calculated as the change in error rate. Post-stimulation learning rate and retention rate were calculated as the change in error rate after stimulation and on the day after stimulation, respectively. In both the stimulation groups, differences in pre-stimulation learning, post-stimulation learning, and retention rates were not significant. However, in the γ-tACS group, baseline performance and pre-stimulation learning rate were positively correlated with post-stimulation learning rate. Therefore, applying γ-tACS to the SMA can increase post-stimulation learning rate in participants exhibiting low baseline performance and high pre-stimulation learning rate. Our findings suggest that motor learning can be effectively enhanced by applying γ-tACS to the SMA based on an individual's motor and learning abilities.

A longitudinal event-related potentials study of idiom processing in healthy elderly adults

A longitudinal event-related potentials study of idiom processing in healthy elderly adults

Effects of vitamin D3, omega-3s, and a simple strength training exercise program on bone health: the DO-HEALTH randomized controlled trial.

Evidence on the effects of Vitamin D, omega-3s, and exercise on areal bone mineral density (aBMD) in healthy older adults is limited. We examined whether vitamin D3, omega-3s, or a simple home-based exercise program (SHEP), alone or in combination, over 3 years, improve lumbar spine (LS), femoral neck (FN), or total hip (TH) aBMD assessed by DXA. Areal BMD was a secondary outcome in DO-HEALTH, a 3-year, multicenter, double-blind, randomized 2 × 2 × 2 factorial design trial in generally healthy older adults age ≥ 70years. The study interventions were vitamin D3 (2000IU/d), omega-3s (1g/d), and SHEP (3 × 30min/wk), applied alone or in combination in eight treatment arms. Mixed effects models were used, adjusting for age, sex, BMI, prior fall, study site, and baseline level of the outcome. Main effects were assessed in the absence of an interaction between the interventions. Subgroup analyses by age, sex, physical activity level, dietary calcium intake, serum 25(OH)D levels, and fracture history were conducted. DXA scans were available for 1493 participants (mean age 75years; 80.4% were physically active, 44% had 25(OH)D levels <20ng/mL). At the LS and FN sites, none of the treatments showed a benefit. At the TH, vitamin D versus no vitamin D treatment showed a significant benefit across 3years (difference in adjusted means [AM]: 0.0035 [95% CI, 0.0011, 0.0059] g/cm). Furthermore, there was a benefit for vitamin D versus no vitamin D treatment on LS aBMD in the male subgroup (interaction P = .003; ∆AM: 0.0070 [95% CI, 0.0007, 0.0132] g/cm). Omega-3s and SHEP had no benefit on aBMD in healthy, active, and largely vitamin D replete older adults. Our study suggests a small benefit of 2000IU vitamin D daily on TH aBMD overall and LS aBMD among men; however, effect sizes were very modest and the clinical impact of these findings is unclear.

The bioaccessibility and tolerability of marine-derived sources of magnesium and calcium

It is generally accepted that mineral deficiencies, including magnesium and calcium, are widespread globally. Dietary supplementation may be an effective approach to combat such deficiencies. However, challenges associated with limited mineral solubility in the digestive system can impede effective dissolution and hinder absorption, leading to deficiency, and undesirable gastrointestinal disturbances including diarrhoea. Seawater is considered to be a rich source of bioactive magnesium, calcium, and 72 other trace minerals. In this study, we examine two different marine-derived multimineral products as potential dietary supplements. Aquamin-Mg, sourced from seawater is rich in magnesium (12%), and Aquamin F, a seaweed-derived multimineral is rich in calcium (32%). Both products also contain a diverse array of over 72 minerals, characteristic of their oceanic origin. Our study comprises two experiments. The first experiment evaluates and compares the solubility of Aquamin-Mg, commercially available magnesium bisglycinate, and Pure Magnesium Bisglycinate (PrizMAG) during in vitro digestion using the INFOGEST method. Results demonstrate that Aquamin-Mg exhibits superior solubility than the other magnesium sources during the gastric and intestinal phases, particularly when administered alongside food materials. The second experiment is a randomized, double-blind, placebo-controlled study in a small cohort of healthy older aged adults to assess the tolerability of a combined Aquamin-Mg/Aquamin-F supplement over a 12-week period. The findings indicate that this combination supplement is well-tolerated, with no significant adverse events reported, emphasizing its potential as a means of addressing mineral deficiencies.

Assessing Adhesiveness Levels in a Dysphagia Diet for Older Adults.

Viscosity is a common focus in the diet of patients with dysphagia. However, adhesiveness is an equally significant property that can affect swallowing function, even in semi-solid foods with similar levels of viscosity. The purpose of this study was to classify the adhesiveness of food into stages and determine whether these classifications are relevant to swallowing function. This study included 30 healthy elderly adults aged 65 years. After categorizing adhesiveness into three levels based on the results of the sensory test, 30 participants were asked to swallow representative foods at each level. A videofluoroscopic swallowing study (VFSS) was performed to determine the presence or absence of pharyngeal residues based on the level of adhesiveness. The chi-square test was used to verify whether there was a difference in remnants according to the level of adhesiveness, and significance was judged with a p-value of less than 0.05. Adhesiveness was categorized into three distinct levels: level 1 (0-4 mJ), level 2 (4-18 mJ), and level 3 (>18 mJ). Upon examining the subjects presenting with residual material, we observed three cases of level 1 adhesiveness, 16 cases of level 2, and 25 cases of level 3. The chi-square test was used to assess the statistical significance between the levels, revealing a significant difference with a p-value < 0.0001. We presented the level of adhesiveness by dividing it into three stages and proved that it is meaningful in relation to the swallowing function. Selecting and recommending foods with an appropriate level of adhesiveness will help enhance swallowing safety in older adults.

How outdoor horticultural activities affect elderly adults' thermal, physiological and psychological responses: a field study.

We recruited 162 healthy elderly adults to determine the thermal, physiological, and psychological effects of horticultural activities (flower arranging, transplanting, and rubble masonry) in outdoor open spaces. We linked these to local climate conditions, physiology, and comfort through a questionnaire survey. The results showed that: (1) the neutral physiological equivalent temperature (NPET) before the horticultural activities were 22.18℃ for flower arranging, 23.67℃ for transplanting, and 20.78℃ for rubble masonry, while the NPET decreased to 18.53℃, 20.73℃ and 18.04℃ (respectively) after activities. (2) The heart rate and blood oxygen saturation changed significantly (p < 0.05) only after rubble masonry. (3) The average positive affect (PA) scores increased after flower arranging by 4.83, transplanting by 3.30, and rubble masonry by 4.00. (4) After activities, the thermal sensation vote was mainly influenced by globe temperature (41.36%), air temperature (33.47%), and wind speed (25.17%). Thermal comfort vote could be promoted because of 37.35% of an increasing positive and 21.20% of decreasing negative emotion.

Effects of Audio-visual and Contextual Conditions on Auditory Word Recognition in Patients with Normal Pressure Hydrocephalus

Objectives: In this study, we compared performance on the auditory word recognition tasks between patients with normal pressure hydrocephalus (NPH) and healthy elderly adults (HE) under different visual, auditory, and contextual conditions to determine how these variables affect auditory comprehension with cognitive decline.Methods: We conducted a standardized comprehension assessment, Paradise Korean Western Aphasia Battery Revised (PK-WAB-R) and the auditory word recognition tasks on 30 patients with NPH and 30 HE. The auditory word recognition task was divided into noisy and quiet conditions (auditory variable), blurry and clean conditions (visual variable), and low- and high-context conditions (contextual variable).Results: Patients with NPH showed relatively good comprehension on the standardized comprehension test of PK-WAB-R. For the auditory word recognition tasks, there was a significant main effect of group, a significant within-group effect of auditory and contextual conditions, and significant interaction effects between auditory condition and group, auditory condition and contextual information, and auditory condition, contextual information, and group.Conclusion: This study confirmed that patients with NPH have difficulty processing auditory comprehension at the sentence level. In addition, the auditory word recognition performance in patients with NPH was significantly lower than HE, and that their difficulties may be more pronounced under certain conditions, such as noisy conditions and low contextual information.

Modeling the neurocognitive dynamics of language across the lifespan.

Healthy aging is associated with a heterogeneous decline across cognitive functions, typically observed between language comprehension and language production (LP). Examining resting-state fMRI and neuropsychological data from 628 healthy adults (age 18-88) from the CamCAN cohort, we performed state-of-the-art graph theoretical analysis to uncover the neural mechanisms underlying this variability. At the cognitive level, our findings suggest that LP is not an isolated function but is modulated throughout the lifespan by the extent of inter-cognitive synergy between semantic and domain-general processes. At the cerebral level, we show that default mode network (DMN) suppression coupled with fronto-parietal network (FPN) integration is the way for the brain to compensate for the effects of dedifferentiation at a minimal cost, efficiently mitigating the age-related decline in LP. Relatedly, reduced DMN suppression in midlife could compromise the ability to manage the cost of FPN integration. This may prompt older adults to adopt a more cost-efficient compensatory strategy that maintains global homeostasis at the expense of LP performances. Taken together, we propose that midlife represents a critical neurocognitive juncture that signifies the onset of LP decline, as older adults gradually lose control over semantic representations. We summarize our findings in a novel synergistic, economical, nonlinear, emergent, cognitive aging model, integrating connectomic and cognitive dimensions within a complex system perspective.

Cardiorespiratory rhythm-contingent trace eyeblink conditioning in elderly adults.

Learning outcome is modified by the degree to which the subject responds and pays attention to specific stimuli. Our recent research suggests that presenting stimuli in contingency with a specific phase of the cardiorespiratory rhythm might expedite learning. Specifically, expiration-diastole (EXP-DIA) is beneficial for learning trace eyeblink conditioning (TEBC) compared with inspiration-systole (INS-SYS) in healthy young adults. The aim of this study was to investigate whether the same holds true in healthy elderly adults (n = 50, aged >70 yr). Participants were instructed to watch a silent nature film while TEBC trials were presented at either INS-SYS or EXP-DIA (separate groups). Learned responses were determined as eyeblinks occurring after the tone conditioned stimulus (CS), immediately preceding the air puff unconditioned stimulus (US). Participants were classified as learners if they made at least five conditioned responses (CRs). Brain responses to the stimuli were measured by electroencephalogram (EEG). Memory for the film and awareness of the CS-US contingency were evaluated with a questionnaire. As a result, participants showed robust brain responses to the CS, acquired CRs, and reported awareness of the CS-US relationship to a variable degree. There was no difference between the INS-SYS and EXP-DIA groups in any of the above. However, when only participants who learned were considered, those trained at EXP-DIA (n = 11) made more CRs than those trained at INS-SYS (n = 13). Thus, learned performance could be facilitated in those elderly who learned. However, training at a specific phase of cardiorespiratory rhythm did not increase the proportion of participants who learned.NEW & NOTEWORTHY We trained healthy elderly individuals in trace eyeblink conditioning, either at inspiration-systole or at expiration-diastole. Those who learned exhibited more conditioned responses when trained at expiration-diastole rather than inspiration-systole. However, there was no difference between the experimental groups in the proportion of individuals who learned or did not learn.

Healthy Aging and Older Adults With Autism: A Scoping Review.

Autism spectrum disorder is a lifelong diagnosis. Although several studies have examined the effects of autism throughout childhood, few have considered older adulthood and the difference between the allistic (i.e., persons who are not autistic) population and autistic older adults. In literature regarding healthy aging, there is sparse evidence regarding the intersections of older adulthood and autism. The purpose of this scoping review was to examine the state of literature regarding autistic older adults and the domains of healthy aging, utilizing the framework conceived by Arksey and O'Malley (Scoping studies: Towards a methodological framework. International Journal of Social Research Methodology, 2005;8(1): 19-32. doi:10.1080/1364557032000119616). To identify the research question, we took the following steps: identify the relevant studies; select studies; chart the data; and collate, summarize, and report the results. The specific domains of healthy aging considered include physical health, mobility, mental health, cognition and memory, and social connectedness. A total of 35 articles were selected for final review. Fifty-seven percent of these studies considered only 1 domain of healthy aging, 23% studied 2 domains, whereas 14% measured 3 domains and 6% assessed 4 domains. No study considered all 5 domains. Of the 5 domains considered for this scoping review, mental health and cognition and memory were the most represented domains in the studies. Overall, healthy aging among autistic older adults is largely understudied. More research is needed to better identify and tailor interventions and services for autistic older adults and their families to support healthy aging.

Effects of Low-Load Blood Flow Restriction Training on Muscle Anabolism Biomarkers and Thrombotic Biomarkers Compared with Traditional Training in Healthy Adults Older Than 60 Years: Systematic Review and Meta-Analysis.

The aim of this meta-analysis was to determine the effects of low-load blood flow restriction training (LL-BFRT) on muscle anabolism and thrombotic biomarkers compared with the effects of traditional LL training and to analyse the changes in these biomarkers in the short and medium term (acute/immediate and after at least 4 weeks of the training programme, respectively). A search was conducted in the following electronic databases from inception to 1 March 2024: MEDLINE, CENTRAL, Web of Science, PEDro, Science Direct, CINHAL, and Scopus. A total of 13 randomized controlled trials were included, with a total of 256 healthy older adults (mean (min-max) age 68 (62-71) years, 44.53% female). The outcome measures were muscle anabolism biomarkers and thrombosis biomarkers. The standardized mean difference (SMD) was calculated to compare the outcomes reported by the studies. The overall meta-analysis showed that LL-BFRT produces a large increase in muscle anabolism biomarkers compared with traditional LL training (eight studies; SMD = 0.88 [0.39; 1.37]) and compared with a passive control (four studies; SMD = 0.91 [0.54; 1.29]). LL-BFRT does not produce an increase in thrombotic biomarkers compared with traditional LL training (four studies; SMD = -0.02 [-0.41; 0.36]) or compared with a passive control (two studies; SMD = 0.20 [-0.41; 0.80]). The increase in muscle anabolism biomarkers was large after applying a single session (four studies; SMD = 1.29 [0.18; 2.41]) and moderate after applying a training programme (four studies; SMD = 0.58 [0.09; 1.06]). In conclusion, LL-BFRT increases muscle anabolism biomarkers to a greater extent than traditional LL training (low-quality evidence) or a passive control (moderate-quality evidence) in healthy older adults. This superior anabolic potential of LL-BFRT compared with LL training is sustained in the short to medium term. LL-BFRT is a safe training methodology for older adults, showing moderate-quality evidence of no increase in thrombotic biomarkers compared with traditional LL training.

Abstract P299: Alteration of Cardiac Autonomic Function Through Inhalation of Biogenic Volatile Organic Compounds

Background: There is an inverse relationship between exposure to greenspaces and prevalence of cardiovascular disease and cardiovascular disease risk factors. More specifically, green exposure is associated with electrocardiogram (ECG) changes, suggesting a potential alteration of cardiac autonomic balance. One proposed mechanism by which cardiac autonomic balance may be altered is a direct physiologic effect of inhalable plant derived compounds, or biogenic volatile organic compounds (bVOCs), including limonene, α- and β-pinene which are commonly released from vegetation. Therefore, we examined the relationship between acute exposure of isolated bVOCs and cardiac autonomic tone. Hypothesis: We hypothesize that controlled exposure to isolated individual bVOCs will decrease cardiac sympathetic tone. Methods: Under controlled conditions after a bVOC washout period, healthy adults ages 18-70 were exposed to limonene (n=32), α-pinene (n=24), β-pinene (n=17), and a control (room air, n=9). Exposure consisted of one inhalation every 30 seconds for a total of 5 minutes (10 inhalations total). Pre- and post-exposure measurements of supine heart rate variability (HRV) were conducted following a 10-minute rest period. HRV was analyzed using a clean, 5-minute epoch with &gt;95% effective data length. Statistical analysis was performed using paired t-tests to determine changes in HR and HRV. Significance level was set at p&lt;0.05, a priori . Results: Our population was primarily female (56%, 18 of 32), white (53%, 17 of 32), high income (47%, 15 of 32), and had an education higher than a 4-year degree (62.5%, 20 of 32). There were significant decreases in HR when exposed to limonene (pre: 64.87±9.86bpm vs. post: 63.26±9.10bpm, p&lt;.001) and α-pinene (pre: 63.98±9.32bpm vs. post: 61.64±9.72bpm, p=.008), along with trends seen in β-pinene (pre: 65.78±10.60bpm vs. post: 63.74±9.65bpm, p=.066). Control exposure showed no difference (pre: 65.40±8.38bpm vs. post: 64.14±9.35bpm, p=.301). Normalized low- (LF) and high-frequency (HF) HRV parameters showed no change across isolated bVOCs, however the LF/HF ratio scores decreased significantly following β-pinene exposure (pre: 1.62±1.69 vs. post: 0.96±0.96, p=.039). HRV time-domain parameters RMSSD and SDNN did not change following isolate exposure. Conclusions: Post-exposure decreases in HR and LFHF ratios indicate the potential for cardiovascular disease risk reduction from bVOC exposure leading to decreased sympathetic tone. Additional work is required to determine the mechanism of exposure-related changes.

Regional covariance of white matter hyperintensity volume patterns associated with hippocampal volume in healthy aging.

Hippocampal volume is particularly sensitive to the accumulation of total brain white matter hyperintensity volume (WMH) in aging, but how the regional distribution of WMH volume differentially impacts the hippocampus has been less studied. In a cohort of 194 healthy older adults ages 50-89, we used a multivariate statistical method, the Scaled Subprofile Model (SSM), to (1) identify patterns of regional WMH differences related to left and right hippocampal volumes, (2) examine associations between the multimodal neuroimaging covariance patterns and demographic characteristics, and (3) investigate the relation of the patterns to subjective and objective memory in healthy aging. We established network covariance patterns of regional WMH volume differences associated with greater left and right hippocampal volumes, which were characterized by reductions in left temporal and right parietal WMH volumes and relative increases in bilateral occipital WMH volumes. Additionally, we observed lower expression of these hippocampal-related regional WMH patterns were significantly associated with increasing age and greater subjective memory complaints, but not objective memory performance in this healthy older adult cohort. Our findings indicate that, in cognitively healthy older adults, left and right hippocampal volume reductions were associated with differences in the regional distribution of WMH volumes, which were exacerbated by advancing age and related to greater subjective memory complaints. Multivariate network analyses, like SSM, may help elucidate important early effects of regional WMH volume on brain and cognitive aging in healthy older adults.

Investigating Biomechanical Postural Control Strategies in Healthy Aging Adults and Survivors of Stroke

As the aging populations, both nationwide and worldwide, rapidly increase, falls leading to unintentional injury and death subsequently increase. Thus, developing an understanding of biomechanical postural control strategies used to maintain balance in aging healthy adults, and those that have suffered stroke, are critical. Here, we were interested in how one’s body segments stabilize relative to one another, and in space, in order to maintain balance. To accomplish this goal, we studied 30 healthy individuals and 8 survivors of stroke between 60 and 85 years old, both before and after several weeks of sensory training. Motion capture data were acquired to assess participants’ body kinematics during walking: forward (easiest), forward-tandem, backward, and backward-tandem walking (most challenging). Deviations (via the observation of the absolute angle with deviations, or AADs) of the head, thorax, and lumbar areas relative to an earth vertical reference, as well as how one body segment stabilized in space or relative to the inferior body segment (via the observation of anchoring indices, or AIs), were explored. The results provide metrics (AADs and AIs) that can assess aging posture. Further, the results show an initial indication that, for aging individuals, training could lead to improved head and body stabilization in space.

Scapular motion during shoulder joint extension movement

A few reports on scapular motion during shoulder joint extension exist. Understanding the normal motion of shoulder joint extension may be useful in evaluating and treating patients with diminished or minimal shoulder joint extension. Therefore, this study aimed to identify scapular motion during shoulder joint extension movement in a sitting position. Shoulder joint extension movement in the sitting position were measured in 22 healthy adults (age, 25.8 ± 2.7 years). Shoulder joint extension, scapular upward rotation, anterior tilt, external rotation angles, and the acromion position were investigated using a three-dimensional motion analyzer. The difference from each value of 10° to 50° shoulder joint extension to each value of 0° shoulder joint extension were checked. The results were compared using multiple comparison method. In most participants, the scapula tilted posteriorly up to 30° of the shoulder joint extension and anteriorly after 30°. Scapular upward and external rotation continued to increase with shoulder extension. Furthermore, the acromion was displaced upward and backward. Thus, scapular posterior tilt is necessary for shoulder joint extension during the initial movement, followed by anterior tilt. The acromion may have been displaced posteriorly because of clavicular retraction, causing the scapula to tilt posteriorly. After 30° of shoulder joint extension, the scapular anterior tilt may have prevailed over the scapular posterior tilt.

Vertical Center-of-Mass Braking and Motor Performance during Gait Initiation in Young Healthy Adults, Elderly Healthy Adults, and Patients with Parkinson's Disease: A Comparison of Force-Plate and Markerless Motion Capture Systems.

This study tested the agreement between a markerless motion capture system and force-plate system ("gold standard") to quantify stability control and motor performance during gait initiation. Healthy adults (young and elderly) and patients with Parkinson's disease performed gait initiation series at spontaneous and maximal velocity on a system of two force-plates placed in series while being filmed by a markerless motion capture system. Signals from both systems were used to compute the peak of forward center-of-mass velocity (indicator of motor performance) and the braking index (indicator of stability control). Descriptive statistics indicated that both systems detected between-group differences and velocity effects similarly, while a Bland-Altman plot analysis showed that mean biases of both biomechanical indicators were virtually zero in all groups and conditions. Bayes factor 01 indicated strong (braking index) and moderate (motor performance) evidence that both systems provided equivalent values. However, a trial-by-trial analysis of Bland-Altman plots revealed the possibility of differences >10% between the two systems. Although non-negligible differences do occur, a markerless motion capture system appears to be as efficient as a force-plate system in detecting Parkinson's disease and velocity condition effects on the braking index and motor performance.

Effects of transcranial direct current stimulation on motor learning in healthy elderly individuals: a systematic review and meta-analysis

Background Transcranial direct current stimulation (tDCS) is widely used in motor recovery. Nevertheless, whether tDCS improves motor learning in healthy older adults is still controversial. This review aims to investigate the effectiveness of tDCS on motor learning in healthy elderly individuals. Methods The PubMed, Cochrane Library, Web of Science and Embase databases were initially searched from inception to December 5, 2022. The standard mean difference (SMD) with the corresponding 95% confidence intervals (CIs) were analysed via random-effect models. Results Compared with the sham group, no significant effects were found regarding improvement in motor learning based on the speed or accuracy of the task and reaction time for the tDCS intervention group. After subgroup analysis, a significant effect was found for improved motor learning based on reaction time in the primary motor cortex (M1)-cerebellar group. Conclusions This review revealed that tDCS had no significant effect on improving the speed or accuracy of motor learning in healthy elderly adults. However, it has a significant effect on improving the motor learning ability based on the reaction time of the task (mainly referring to the tDCS stimulation position of M1 and cerebellar), although the results have obvious heterogeneity and uncertainty.