Serial Subtraction Research Articles

Dual-task performance during the Timed Up and Go test in Parkinson's disease - the impact of freezing and cognition

BackgroundDual-task interference (DTI) on gait is well documented in Parkinson’s disease (PD), but how dual-tasks affect functional mobility is less known. Understanding how cognition and freezing of gait (FOG) further impact dual-task ability is important for risk assessment and subsequent delivery of targeted rehabilitation. Research questionWhat is the DTI on completion time of the Timed Up and Go, and DTI on response rate of a serial subtraction task when performed simultaneously, and is DTI impacted by FOG or cognition? MethodsA cross-sectional study design was used. Demographic and clinical characteristics of participants were collected, including global cognition and self-reported FOG. The TUG test was performed with and without a serial subtraction task. Completion times on TUG and response rates on the serial subtraction task was compared between single and dual-task performance using paired samples t-test or Wilcoxon signed rank test as appropriate. Prioritization between tasks was compared with one-sample Wilcoxon signed rank test. The impact of FOG and cognition was investigated with multiple linear regression, controlling for age, sex, and disease severity. ResultsA total of 77 people with mild to moderate PD were included. Significant DTI was observed for both the gait (TUG) and cognitive (response rate) tasks. No statistically significant pattern of prioritization was observed between motor and cognitive tasks. Global cognition was significantly related to both completion time and response rate in single and dual-tasking, whereas FOG was not found to be associated to the outcomes in either condition. SignificanceCognition appears to significantly relate to performance of functional mobility in single and dual-task conditions, which should be considered during routine mobility assessments in people with PD.

The impact of cannabidiol placebo on amygdala-based neural responses to an acute stressor.

Cannabidiol (CBD) impacts brain regions implicated in anxiety reactivity and stress reactivity (e.g., amygdala, anterior cingulate cortex (ACC), anterior insula (AI)); however, placebo-controlled studies are mixed regarding CBD's anxiolytic effects. We previously reported that CBD expectancy alone can alter subjective, physiological, and endocrine markers of stress/anxiety; however, it is unclear whether these findings reflect altered brain reactivity. This study evaluated whether CBD expectancy independently alters amygdala resting-state functional connectivity (rsFC) with the ACC and AI following acute stress. Thirty-eight (20 females) healthy adults were randomly assigned to receive accurate or inaccurate information regarding the CBD content of a CBD-free oil administered during a single experimental session. Following a baseline resting state MRI scan, participants administered their assigned oil sublingually, engaged in a stress task (serial subtraction with negative feedback) inside the scanner, and underwent another resting state MRI scan. Amygdala rsFC with the ACC and AI was measured during each scan, and the subjective state was assessed at six time points. Outcomes were analyzed using ANCOVA. CBD expectancy (vs CBD-free expectancy) was associated with significantly weaker rsFC between the left amygdala and right ACC (p = 0.042), but did not systematically alter amygdala-AI rsFC (p-values > 0.05). We also replicated our previously reported CBD expectancy effects on subjective stress/anxiety in the scanner context. CBD placebo effects may be sufficient to alter neural responses relevant to its purported anxiolytic and stress-relieving properties. Future work is needed to replicate these results and determine whether CBD expectancy and pharmacology interact to alter neural anxiety reactivity and stress reactivity.

Physical activity initiated from midlife on risk of dementia and cognitive impairment: The Health and Retirement Study.

Physical activity is associated with lower risk of dementia and cognitive impairment, but existing randomized controlled trials have shown conflicting results. As cognitive decline occurs decades before the onset of dementia, physical activity interventions initiated in late life may have missed the potential window for prevention. An ideal trial of physical activity initiated from midlife and lasts till incident dementia and cognitive impairment in late life is not feasible. We aimed to estimate the effectiveness of a hypothetical physical activity intervention initiated from midlife on reducing dementia and cognitive impairment by emulating target trials using observational data. The Health and Retirement Study was used to emulate target trials among noninstitutionalized participants aged 45 to 65 years with normal cognition who were physically inactive in the previous 2 years. Cognitive status was determined based on Langa-Weir classification of cognitive function (including immediate and delayed word recall tests, serial sevens subtraction, counting backward). Individuals were categorized as initiating physical activity or not, based on the self-reported physical activity. Intention-to-treat and per-protocol analysis were conducted with pooled logistic regression models with inverse-probability of treatment and censoring weights to estimate risk ratios (RRs), and 95% confidence intervals (95% CIs) were calculated with 200 sets of bootstrapping. Among 1505 participants (average age 57.6 ± 4.8 years, 67% women, 76.5% White), 72 cases of dementia and 409 cases of cognitive impairment occurred. After 12 years of follow-up, physical activity reduced dementia (RR = 0.70, 95% CI: 0.43, 0.99) for intention-to-treat analysis, and reduced dementia (RR = 0.51, 95% CI: 0.19, 0.99) and cognitive impairment (RR = 0.77, 95% CI: 0.61, 0.92) for per-protocol analysis. No significant reduction was found among older adults. Physical activity initiated during midlife may reduce dementia and cognitive impairment in late life, which highlights the importance of preventing cognitive outcomes at an earlier stage of life.

Association of dual task gait performance with cognitive outcomes among older adults: Piloting an inexpensive, portable assessment platform

Motor assessment has emerged as complementary evidence for the detection of late life cognitive disorders. Clinicians lack inexpensive, accurate, and portable tools for this purpose. To fill this void, the current study piloted measures from the Mizzou Point-of-care Assessment System a multimodal sensor platform. We examined the ability of these motor function measures to distinguish neurocognitive status and assessed their associations with cognitive performance. Data came from 42 older adults, including 16 with mild cognitive impairment (MCI). Participants performed dual task gait, pairing walking with serial subtraction by sevens, along with aa neuropsychological test battery. T-tests revealed that individuals with MCI demonstrated slower stride times (d = .55) and shorter stride lengths (d = .98) compared to healthy older adults. Results from hierarchical regression showed that stride time and stride length predicted cognitive performance across several domains, after controlling for cognitive status and demographics. Cognitive status moderated this relationship for global cognition and attention, wherein gait measures were significantly related to these outcomes for the cognitively normal group, but not the MCI group. Evidence from the current study provided preliminary support that MPASS measures demonstrate expected associations with cognitive performance and can distinguish amongst those with and without cognitive impairment.

Does electronic cigarette use adversely affect cardiac autonomic function?

Introduction: tobacco cigarette (TC) smoking is a predominant risk factor for cardiovascular disease and a leading preventable cause of death (Kondo et al., 2019, Circ J, 83, 1980-1985). Electronic Cigarette (EC) use has increased significantly in recent years (King et al., 2015, Nic Tob Res, 17, 219-227), mainly as it is considered a safer alternative to TC. A low heartrate variability (HRV) is an independent marker of adverse cardiovascular morbidity and all-cause mortality (Fang et al., 2020, Bio Res Nur, 22, 45-56). TC smokers have a lower HRV, and similar responses have now also been observed in EC smokers (Arastoo et al., 2020, Am J Physiol Heart Circ Physiol, 319, 262-270). However, the influence of cognitive / psychological stress on HRV in TC and EC users remains unexplored. As such, this study aims to assess the impact of cognitive stress on Time and Frequency domain measures of HRV. Methods: upon receiving ethical approval, HRV data was collected through electrocardiogram (ECG) recordings of healthy controls (HC), TC and EC smokers which were recorded using lead II ECG at 1000 Hz on LabChart during periods of rest (5 min) and cognitive stress (serial subtraction; 5 min). Time and frequency domain measures of HRV were assessed with LabChart. Data will be compared between groups using one-way analysis of variance (ANOVA) and two-way mixed methods ANOVA as appropriate. Conclusions: we hypothesise that EC smokers will present similar impaired autonomic function and reduced HRV as TC smokers during rest and cognitive stress in comparison to HC.

Walking on a Balance Beam as a New Measure of Dynamic Balance to Predict Falls in Older Adults and Patients with Neurological Conditions.

Beam walking is a new test to estimate dynamic balance. We characterized dynamic balance measured by the distance walked on beams of different widths in five age groups of healthy adults (20, 30, 40, 50, 60years) and individuals with neurological conditions (i.e., Parkinson, multiple sclerosis, stroke, age: 66.9years) and determined if beam walking distance predicted prospective falls over 12months. Individuals with (n = 97) and without neurological conditions (n = 99, healthy adults, age 20-60) participated in this prospective longitudinal study. Falls analyses over 12months were conducted. The summed distance walked under single (walking only) and dual-task conditions (walking and serial subtraction by 7 between 300 to 900) on three beams (4, 8, and 12-cm wide) was used in the analyses. Additional functional tests comprised grip strength and the Short Physical Performance Battery. Beam walking distance was unaffected on the 12-cm-wide beam in the healthy adult groups. The distance walked on the 8-cm-wide beam decreased by 0.34m in the 20-year-old group. This reduction was ~ 3 × greater, 1.1m, in the 60-year-old group. In patients, beam walking distances decreased sharply by 0.8m on the 8 versus 12cm beam and by additional 1.6m on the 4 versus 8cm beam. Beam walking distance under single and dual-task conditions was linearly but weakly associated with age (R2 = 0.21 for single task, R2 = 0.27 for dual-task). Age, disease, and beam width affected distance walked on the beam. Beam walking distance predicted future falls in the combined population of healthy adults and patients with neurological conditions. Based on receiver operating characteristic curve analyses using data from the entire study population, walking ~ 8.0 of the 12m maximum on low-lying beams predicted future fallers with reasonable accuracy. Balance beam walking is a new but worthwhile measure of dynamic balance to predict falls in the combined population of healthy adults and patients with neurological conditions. Future studies are needed to evaluate the predictive capability of beam walking separately in more homogenous populations. Clinical Trial Registration Number NCT03532984.

Impaired Neuromotor Control During Gait in Concussed Adolescents-A Frequency Analysis.

Disruptions in gait function are common after concussion in adolescents; however, the neuromotor control deficits driving these gait disruptions are not well known. Fifteen concussed (age mean [SD]): 17.4 [0.6], 13 females, days since injury: 26.3 [9.9]) and 17 uninjured (age: 18.0 [0.7], 10 females) adolescents completed 3 trials each of single-task gait and dual-task gait (DT). During DT, participants simultaneously walked while completing a serial subtraction task. Gait metrics and variability in instantaneous mean frequency in lower extremity muscles were captured by inertial sensors and surface electromyography, respectively. A 2-way analysis of covariance was used to compare gait metrics across groups and conditions. Functional principal components analysis was used to identify regions of variability in instantaneous mean frequency curves. Functional principal component scores were compared across groups using a Welch statistic. Both groups displayed worse performance on gait metrics during DT condition compared to single-task, with no differences between groups (P < .001). Concussed adolescents displayed significantly greater instantaneous mean frequency, indicated by functional principal component 1, in the tibialis anterior, biceps femoris, and semitendinosus (P < .05) during single-task and DT compared with uninjured adolescents. Our observations suggest that concussed adolescents display inefficient motor unit recruitment lasting longer than 2weeks following injury, regardless of the addition of a secondary task.

How does a motor or cognitive dual-task affect our sense of upper limb proprioception?

Daily upper limb activities require multitasking and our division of attention. How we allocate our attention can be studied using dual-task interference (DTi). Given the vital role proprioception plays in movement planning and motor control, it is important to investigate how conscious upper limb proprioception is impacted by DTi through cognitive and motor interference. To examine how dual-task interference impacts conscious upper limb proprioception during active joint repositioning tasks (AJRT). Forty-two healthy participants, aged between 18 and 35, took part in this cross-sectional study. Participants completed two AJRT during three conditions: baseline (single task), dual-cognitive task (serial subtractions), and dual-motor task (non-dominant hand movements). The proprioceptive error (PE; difference between their estimation and targeted position) was measured using an AJRT of 75% and 90% of maximum internal rotation using the Biodex System IIITM and the Upper Limb Proprioception Reaching Test (PRO-Reach). To determine if PEs differed during dual-task interference, interference change scores from baseline were used with one sample t-tests and analyses of variance. The overall mean PE with the Biodex was 4.1° ± 1.9 at baseline. Mean change scores from baseline reflect a mean improvement of 1.5° ± 1.0 (p < .001) during dual-cognitive task and of 1.5° ± 1.2 (p < .001) during dual-motor task. The overall mean PE with the PRO-Reach was 4.4cm ± 1.1 at baseline. Mean change scores from baseline reflect a mean worsening of 1.0cm ± 1.1 (p < .001) during dual-cognitive task and improvement of 0.8cm ± 0.6 (p < .001) during dual-motor task. Analysis of variance with the Biodex PEs revealed an interference effect (p < .001), with the cognitive condition causing greater PEs compared to the motor condition and a criterion position effect (p = .006), where 75% of maximum IR produced larger PEs during both interference conditions. An interference effect (p = .022) with the PRO-Reach PEs was found highlighting a difference between the cognitive and motor conditions, with decreased PEs during the contralateral motor task. Interference tasks did impact proprioception. Cognitive interference produced mixed results, whereas improved proprioception was seen during motor interference. Individual task prioritization strategies are possible, where each person may choose their own attention strategy when faced with dual-task interference.

Speaking demands: concurrent visuomotor rotor pursuit tracking measures cognitive load for speech

ABSTRACT Purpose The purpose of this proof-of-principle study was to determine the extent to which concurrent tracking in a visuomotor rotor pursuit task is a feasible task for inferring the attentional load of clinical speaking tasks. The central predictions of the concurrent dual-task paradigm suggest that participants would exhibit performance change on a visuomotor rotor pursuit task during concurrent speech task performance, particularly when performing an attention-demanding speech task. Method Twenty-five participants performed common speech clinical assessment tasks that included syllable repetition, sentence repetition, counting forward by one, or serial subtraction by three, which requires a higher working memory load. All speech tasks were performed as a single-task and under dual-task conditions with a concurrent visuomotor rotor pursuit task. Results Compared to performing the attention-demanding visuomotor rotor pursuit task as a single-task, participants exhibited clear reductions in tracking accuracy (percent time-on-target) when performing under dual-task conditions with a concurrent speech task. A significantly greater reduction in tracking accuracy was observed during dual-task performance with a serial subtraction task than during the more automatic speaking tasks that involved repetition and counting forward. Conclusion These data suggest that dual-task performance of even repetitive speaking tasks introduces an attentional demand that is reflected in dual-task performance of a concurrent visuomotor rotor pursuit task and that this interference may be greater for speech tasks that require more cognitive resources.

Cortical activation and brain network efficiency during dual tasks: An fNIRS study

ObjectiveDual task (DT) is a commonly used paradigm indicative of executive functions. Brain activities during DT walking is usually measured by portable functional near infrared spectroscopy (fNIRS). Previous studies focused on cortical activation in prefrontal cortex and overlooked other brain regions such as sensorimotor cortices. This study is aimed at investigating the modulations of cortical activation and brain network efficiency in multiple brain regions from single to dual tasks with different complexities and their relationships with DT performance. MethodsForty-two healthy adults [12 males; mean age: 27.7 (SD=6.5) years] participated in this study. Participants performed behavioral tasks with portable fNIRS simultaneous recording. There were three parts of behavioral tasks: cognitive tasks while standing (serial subtraction of 3′s and 7′s), walking alone and DT (walk while subtraction, including serial subtraction of 3′s and 7′s). Cognitive cost, walking cost and cost sum (i.e., sum of cognitive and walking costs) were calculated for DT. Cortical activation, local and global network efficiency were calculated for each task. ResultsThe cognitive cost was greater and the walking cost was less during DT with subtraction 3′s compared with 7′s (P’s = 0.032 and 0.019, respectively). Cortical activation and network efficiency were differentially modulated among single and dual tasks (P's < 0.05). Prefrontal activation during DT was positively correlated with DT costs, while network efficiency was negatively correlated with DT costs (P's < 0.05). ConclusionsOur results revealed prefrontal over-activation and reduced network efficiency in individuals with poor DT performance. Our findings suggest that reduced network efficiency could be a possible mechanism contributing to poor DT performance, which is accompanied by compensatory prefrontal over-activation.

Depression of dynamic cerebral autoregulation during neural activation: The role of responders and non-responders

Neurovascular coupling (NVC) interaction with dynamic cerebral autoregulation (dCA) remains unclear. We investigated the effect of task complexity and duration on the interaction with dCA. Sixteen healthy participants (31.6 ± 11.6 years) performed verbal fluency (naming-words (NW)) and serial subtraction (SS) paradigms, of varying complexity, at durations of 05, 30 and 60 s. The autoregulation index (ARI), was estimated from the bilateral middle cerebral artery blood velocity (MCAv) step response, calculated by transfer function analysis (TFA), for each paradigm during unstimulated (2 min) and neuroactivated (1 min) segments. Intraclass correlation (ICC) and coefficient of variation (CV) determined reproducibility for two visits and objective criteria were applied to classify responders (R) and non-responders (NoR) to task-induced MCAv increase. ICC values demonstrated fair reproducibility in all tasks. ARI decreased in right (RH) and left (LH) hemispheres, irrespective of paradigm complexity and duration (p < 0.0001). Bilateral ARI estimates were significantly decreased during NW for the R group only (p < 0.0001) but were reduced in both R (p < 0.0001) and NoR (p = 0.03) groups for SS tasks compared with baseline. The reproducible attenuation of dCA efficiency due to paradigm-induced NVC response, its interaction, and different behaviour in R and NoR, warrant further research in different physiological and clinical conditions.

The Effects of Polyphenol Supplementation on BDNF, Cytokines and Cognition in Trained Male Cyclists following Acute Ozone Exposure during High-Intensity Cycling.

The neurotoxic effects of ozone exposure are related to neuroinflammation and increases in reactive oxygen species (ROS). This study aimed to assess inflammation, Brain-Derived Neurotrophic Factor (BDNF), and cognition in healthy male cyclists following polyphenol supplementation and exercise in an ozone-polluted environment. Ten male cyclists initially completed a maximal incremental test and maximal effort 4 km time trial in ambient air. Cyclists then completed two trials in an ozone-polluted environment (0.25 ppm) following 7 days of supplementation with either polyphenol (POLY) or placebo (PL). Experimental trials consisted of a three-stage submaximal test followed by a 4 km time trial. Blood samples were drawn pre- and post-exercise, and analyzed for BDNF, interleukin 6 (IL-6), interleukin 10 (IL-10) and tumor necrosis factor (TNF-α). The Stroop test and serial subtraction task were performed before ozone exposure and again after the 4 km TT. Serum BDNF increased post-exercise (p < 0.0001), and positive differences were observed post-exercise in the ozone POLY group relative to PL (p = 0.013). Plasma IL-6 increased post-exercise (p = 0.0015), and TNF-α increased post-ozone exposure (p = 0.0018). There were no differences in Stroop or serial subtraction tasks pre- or post-exercise. Exercise increases BDNF in ozone.

Cognitive-motor interference during walking with modified leg mechanics: a dual-task walking study.

The use of mobile exoskeletons as assistive walking devices has the potential to affect the biomechanics of the musculoskeletal system due to their weight and restricted range of motion. This may result in physical and cognitive load for the user. Understanding how lower extremity loading affects cognitive-motor interference is crucial for the design of wearable devices, including powered exoskeletons, and the development of effective training interventions. This study aims to examine the effects of modified leg mechanics on cognitive-motor interference in dual-task walking. Gait variability, as an indicator of motor control, was analyzed to investigate its relation to cognitive task difficulty and to determine whether lower extremity loading modifies this relationship. Additionally, the impact on the gait pattern, as represented by the mean values of spatio-temporal gait parameters were investigated. Fifteen healthy young adults walked on a treadmill with and without weight cuffs bilaterally attached to their thighs and shanks while performing a visual-verbal Stroop test (simple task) and a serial subtraction task (difficult task). Dependent variables include mean values and variability (coefficients of variation) of step length, step width, stride time and double support time. Additionally, secondary task performance as correct response rates and perceived workload were assessed. Double support time variability decreased during dual-task walking, but not during walking with modified leg mechanics while performing the difficult secondary task. Walking with modified leg mechanics resulted in increased gait variability compared to normal walking, regardless of cognitive load. During walking with modified leg mechanics, step length, step width, and stride time increased, while double support time decreased. The secondary tasks did not affect the gait pattern. The interplay between an external focus of attention and competition for attentional resources may influence the variability of double support time. The findings suggest that walking with modified leg mechanics could increase cognitive-motor interference for healthy young adults in demanding dual-task situations. Therefore, it is important to analyze the underlying mechanisms of cognitive-motor interference in the context of human-exoskeleton interaction.

Development and External Validation of a Gait Test Based Diagnostic Model for Detecting Mild Cognitive Impairment

ObjectiveTo address the lack of large-scale screening tools for mild cognitive impairment (MCI), this study aimed to assess the discriminatory ability of several gait tests for MCI and develop a screening tool based on gait test for MCI. DesignA diagnostic case-control test. SettingThe general community. ParticipantsWe recruited 134 older adults (≥65 years) for the derivation sample, comprising -69 individuals in the cognitively normal group and -65 in the MCI group (N=134). An additional 70 participants were enrolled for the validation sample. InterventionsAll participants completed gait tests consisting of a single task (ST) and 3 dual tasks (DTs): counting backwards, serial subtractions 7, and naming animals. Main Outcome MeasuresBinary logistic regression analyses were used to develop models, and the efficacy of each model was assessed using receiver operating characteristic (ROC) curve and area under the curve (AUC). The best effective model was the final diagnostic model and validated using ROC curve and calibration curve. ResultsThe DT gait test incorporating serial subtractions 7 as the cognitive task demonstrated the highest efficacy with the AUC of 0.906 and the accuracy of 0.831 in detecting MCI with “years of education” being adjusted. Furthermore, the model exhibited consistent performance across different age and sex groups. In external validation, the model displayed robust discrimination (AUC=0.913) and calibration (calibrated intercept=-0.062, slope=1.039). ConclusionsThe DT gait test incorporating serial subtractions 7 as the cognitive task demonstrated robust discriminate ability for MCI. This test holds the potential to serve as a large-scale screening tool for MCI, aids in the early detection and intervention of cognitive impairment in older adults.

SLEEP PROBLEMS MEDIATE THE ASSOCIATION BETWEEN CHILDHOOD ADVERSITY AND LATE-LIFE COGNITIVE FUNCTIONING

Abstract The negative health impacts of childhood adversity have been well documented. However, little is known about the pathways linking childhood adversity with cognitive functioning later in life. We addressed this issue by examining the extent to which lifetime sleep problems mediated the effects of childhood adversity on late-life cognitive functioning. We used the 2002-2018 waves of the Health and Retirement Study in which participants were 20,607 adults (58.1% female), aged ≥50 years (Mage=68.9±9.5 years). Cognitive functioning was based on: 1) a 10-word immediate and delayed recall test of memory; 2) a serial 7s subtraction test of working memory; and 3) counting backwards to assess attention and processing speed. Sleep problems (e.g., difficulty initiating sleep) were assessed with the Jenkins Sleep Scale, and seven items of childhood adversity (e.g., physical abuse) were included from the list of lifetime potentially traumatic events. Path analysis revealed that there was a small but significant indirect relationship between childhood adversity and poor cognitive functioning through sleep problems (coefficient = -.014; p=.001). Indeed, about 3% of the effect of childhood adversity on cognitive functioning is mediated by sleep problems (i.e., 0.014 [indirect effect] / 0.476 [total effect]). Our findings can help policymakers and public health practitioners better understand the risk and protective factors of cognitive functioning later in life in relation to sleep problems among those individuals with childhood adverse events. Further research is warranted to determine if childhood adversity contributes to cognitive decline in those with trauma and PTSD compared to those with trauma alone.

TRANSCRANIAL DIRECT CURRENT STIMULATION MODULATES BRAIN ACTIVITY DURING DUAL-TASK STANDING IN OLDER ADULTS

Abstract In older adults, performing an attention-demanding cognitive task while standing comes with a ‘cost’ (i.e., decrement) to postural control. Transcranial direct current stimulation (tDCS) designed to facilitate the excitability of the left dorsal-lateral prefrontal cortex (L-DLPFC) and motor cortex (M1) mitigates this dual-task cost (DTC). The effects of tDCS on underlying brain activity measured by electroencephalography (EEG) during dual-tasking, however, is unknown. We hypothesized that tDCS would decrease the DTC of EEG-measured alpha and gamma power, as these frequencies have been linked to attentional processing and their attenuation is believed to reflect more efficient and/or effective postural control. Thirty participants received 20-minutes of tDCS targeting the L-DLPFC and M1, or sham (i.e., control) stimulation, in random order, on two separate visits. Before and immediately after each stimulation, EEG and postural sway area were recorded as participants completed trials of standing with and without verbalized serial subtractions. EEG alpha and gamma power were derived from channels corresponding to the L-DLPFC and M1 areas. The DTC (absolute change from single to dual-tasking) for both EEG and sway outcomes were calculated. tDCS, compared to sham, decreased the DTC to gamma power (p=0.04) and sway area (p=0.04). No pre-to-post stimulation changes were observed for alpha power (p=0.42). Participants who demonstrated a greater decrease in the DTC to gamma power after tDCS exhibited a greater reduction (improvement) in the DTC to sway area (r=0.66, p=0.002). The results suggest that the tDCS-induced changes in gamma-frequency activity were associated with improved dual-task standing balance in older adults.

Frailty, cognitive impairment, and depressive symptoms in Chinese older adults: an eight-year multi-trajectory analysis

BackgroundFrailty, cognitive impairment, and depressive symptoms are closely interrelated conditions in the aging population. However, limited research has longitudinally analyzed the concurrent trajectories of these three prominent conditions in older adults in China. This study aimed to explore the eight-year trajectories of frailty, cognitive impairment, and depressive symptoms, and to identify individual-level and structural-level factors associated with the trajectories.MethodsFour waves of data from the China Health and Retirement Longitudinal Study (2011–2018) were used to identify 6,106 eligible older adults. The main measures included frailty by the frailty index constructed using 30 indicators, cognitive impairment by the summary score of immediate and delayed word recall, figure drawing, serial subtraction, and orientation, and depressive symptoms by the Center for Epidemiologic Studies Depression Scale. Multi-trajectory models identified the trajectories of frailty, cognitive impairment, and depressive symptoms over time. Multinomial logistic regression was employed to estimate the associations between individual-level capital factors and one structural factor (hukou and geographic residency) with the identified trajectories, adjusting for demographic characteristics.ResultsFour trajectories emerged: (1) worsening frailty, worsening cognitive impairment, depression (14.0%); (2) declining pre-frailty, declining cognition, borderline depression (20.0%); (3) pre-frailty, worsening cognitive impairment, no depression (29.3%); and (4) physically robust, declining cognition, no depression (36.7%). Using the “physically robust, declining cognition, no depression” as the reference, not working, no social activity participant, worse childhood family financial situation, and poorer adult health were most strongly associated with the “worsening frailty, worsening cognitive impairment, depression” trajectory; worse health during childhood had the highest association with the “declining pre-frailty, declining cognition, borderline depression” trajectory; less education, lower household consumption, and rural hukou had the greatest association with the increased likelihood of the “pre-frailty, worsening cognitive impairment, no depression” trajectory.ConclusionsFindings could inform the understanding of the interrelationship of frailty, cognitive impairment, and depressive symptoms in older adults in China and may help practitioners detect adults at risk for adverse trajectories to implement strategies for proper care.

Brain Active Areas Associated with a Mental Arithmetic Task: An eLORETA Study.

The neural underpinnings of mental calculation, the fundamentals of arithmetic representations and processes, and the development of arithmetic abilities have been explored by researchers over the years. In the present work, we report a study that analyzes the brain-activated areas of a group of 35 healthy subjects (9 males, 26 females, mean age ± SD = 18.23 ± 2.20 years) who performed a serial subtraction arithmetic task. In contrast to most of the studies in the literature based on fMRI, we performed the brain active source reconstruction starting from EEG signals by means of the eLORETA method. In particular, the subjects were classified as bad counters or good counters, according to the results of the task, and the brain activity of the two groups was compared. The results were statistically significant only in the beta band, revealing that the left limbic lobe was found to be more active in people showing better performance. The limbic lobe is involved in visuospatial processing, memory, arithmetic fact retrieval, and emotions. However, the role of the limbic lobe in mental arithmetic has been barely explored, so these interesting findings could represent a starting point for future in-depth analyses. Since there is evidence in the literature that the motor system is affected by the execution of arithmetic tasks, a more extensive knowledge of the brain activation associated with arithmetic tasks could be exploited not only for the assessment of mathematical skills but also in the evaluation of motor impairments and, consequently, in rehabilitation for motor disorders.

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 (45-64years), middle-old (65-79years), and oldest-old (≥80years). 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.

2 Clinical Validity and Cut-Off Scores of a Brief Neuropsychological Battery for a Large Rural Population in Community Setting

Objective:There is a dearth of an appropriate standardized tool to assess neuropsychological functions in rural population, which has low literacy rates, are culturally diverse, and have limited access to healthcare resources. The NIREH Neuropsychological Battery for Rural Population (NINB-RP) is a relatively brief and easy-to-administer battery comprising multiple tests that are modified or adopted as per rural community settings to evaluate verbal learning, fine coordination, attention efficiency, executive task, concentration, and visual attention, mental flexibility, and motor coordination in rural populations. The present study aimed to examine the clinical validity and establish cut-off scores for impairment of neuropsychological functions for different age, gender, and education levels of NINB-RP in a rural community in central India.Participants and Methods:This was a prospective cross-sectional study conducted in participants aged &gt; 18 years (n=2952, M: F=1407:1545) recruited through a stratified sampling technique from 23 randomly selected villages from central India. The data of nine neuropsychological tests [(Finger and Tweezer dexterity test (FDT, TDT); Digit Forward and Backward test (DFT, DBT); Serial subtraction test (SST); Trail Making-A and B; Finger Tapping test (FTT); and Letter Digit Substitution test, LDST)] from 215 cognitively impaired and 2737 healthy control subjects were analyzed. The tests were performed in a village school/community hall or an outdoor camp. Independent sample t-test, Chi-square test, and Receiver Operating Characteristic (ROC) curve were used to calculate the area under the curve (AUC), cut-off scores, and sensitivity (ST)/specificity (SP) values for seven conditions, i.e., gender (male vs. female), age groups (up to 49 years and above 50 years); and educational levels (illiterate, intermediate and college). For those variables where ST/SP values were lower than 0.70, a unique cut-off score was calculated for the entire sample, adjusting by age and educational levels.Results:A significant difference in mean (median) scores between the healthy control and cognitively impaired groups were observed in all tests except Trail Making A and B and LDST. The AUC for most of the tests ranged from 0.70 to 0.81, and the ST/SP values ranged from 69-73% and 65-75%, respectively. The results showed that most tests of NINB-RP reached moderate to good sensitivity and specificity for gender, age and education levels, except for DBT for females, above 50 years, and illiterate and intermediate education groups. FDT for males [AUC: 0.85 (95%CI0.80-0.91], ST/SP=76/82%] and females [(AUC=0.78 (95%CI0.74-0.82), ST/SP=71/70%], TDT for intermediate education group [AUC=0.82 (95%CI0.60-1.00), ST/SP=86/83%] and FTT for less than 49 years age group [AUC=0.75 (95%CI0.67-0.84), ST/SP=71/76%] were the most useful tests to discriminate among healthy control and cognitively impaired rural population.Conclusions:The present study is an attempt to establish the cut-off scores of a neuropsychological battery for a large rural population in the community setting. The proposed cut-off values might be helpful in clinical assessment in rural areas where clinical neuropsychology services are not readily available. NINB-RP can be a valuable tool for clinical research studies in rural communities. Further studies on similar samples in other countries need to be undertaken.