Age differences in inhibitory and working memory functioning: limited evidence of system interactions

Debate persists regarding the nature of age-related deficits in inhibition, and whether inhibitory functioning depends on working memory systems. The current research aimed to measure age-related differences in inhibition and working memory, characterize the relationship between inhibitory functions and working memory performance, and determine how these relationships are affected by age. Toward these ends, we measured performance on a range of established paradigms in 60 young adults (18-30 years) and 60 older adults (60-88 years). Our findings support age-related increases in reflexive inhibition (based on the fixation offset effect and inhibition of return) and age-related decrements in volitional inhibition (based on several paradigms: antisaccade, Stroop, flanker, and Simon). This evidence of stronger reflexive inhibition combined with weaker volitional inhibition suggests that age-related deterioration of cortical structures may allow subcortical structures to operate less controlled. Regarding working memory, older adults had lower backward digit scores and lower forward and backward spatial scores. However, of the 32 analyses (16 in each age group) that tested for dependence of inhibitory functioning on working memory functioning, only one (in young adults) indicated that inhibition performance significantly depended on working memory performance. These results indicate that inhibition and working memory function largely independently in both age groups, and age-related working memory difficulties cannot account for age-related declines in inhibitory control.

Back on top: Resuspended by dredging and other environmental disturbances, organochlorine compounds may affect the health of a dolphin population in a tropical estuary, Sepetiba Bay

Organochlorine compounds (OCs) are persistent organic pollutants linked to damaging the immune and endocrine systems, leading to a greater susceptibility to infectious diseases at high concentrations. Sepetiba Bay, in the Southeastern Brazilian coast, historically presents anthropogenic activities and environmental contamination that could negatively impact resident populations. In this context, this study aimed to investigate the temporal trends in the accumulation of organochlorine compounds over a 12-year database in the Guiana dolphins' (Sotalia guianensis) resident population from Sepetiba Bay, including individuals collected before, during, and after an unusual mortality event triggered by morbillivirus (n = 85). The influence of biological parameters was also evaluated. The OCs concentrations in the blubber ranged from 0.98 to 739 μg/g of ΣPCB; 0.08-130 μg/g of ΣDDT; <0.002-4.56 μg/g of mirex; <0.002-1.84 μg/g of ΣHCH and <0.001-0.16 μg/g of HCB in lipid weight. Increased temporal trends were found for OCs in Guiana dolphins coinciding with periods of large events of dredging in the region. In this way, our findings suggest that the constant high OCs concentrations throughout the years in this Guiana dolphin population are a result of the constant environmental disturbance in the area, such as dredging. These elevated OCs levels, e.g., ΣPCB concentrations found above the known thresholds, may impair the response of the immune system during outbreak periods, which could lead the population to a progressive decline.

Chronic exercise and neuropsychological function in healthy young adults: a randomised controlled trial investigating a running intervention

Despite the well-known physical and mental health benefits of regular exercise, many of the world's population, including healthy young adults, grossly undershoot recommended physical activity levels. Chronic exercise has potential to improve cognitive performance and affect in most age groups. However, there is currently a poverty of relevant research in young adults, especially randomised controlled trials. To address this, the current research investigated the effects of a running intervention on neuropsychological function (cognition and affect) in young adults. We predicted that following a running intervention, neuropsychological performance would improve alongside increases in aerobic fitness. Thirty-two healthy young adult university students were randomised (using a 3:1 ratio) into an intervention or control group, with the intervention group (n = 24) asked to run for 30 min three times a week over a 6-week period and the control group (n = 8) asked to maintain their current level of exercise over a 6-week period. We assessed fitness, cognitive performance, affect and running enjoyment at baseline and follow-up, and runners recorded the environmental conditions of their runs. Repeated measures ANCOVAs failed to find any significant effects of the running intervention on fitness or the neuropsychological measures. Anecdotal evidence supported running environment and enjoyment as potentially relevant factors. The failure to find any fitness improvements, which likely underpins the lack of neuropsychological improvements, highlights the importance of monitoring exercise sessions. Coupled with other insights gained from this trial, this article may prove useful towards future endeavours to develop exercise interventions beneficial to young adults.TRN: ACTRN12621000242820, Date of registration: 08/03/2021.

3-Year test-retest reliability in Parkinson's disease and healthy older adults: The Parkinson's progression markers initiative study

Repeated neuropsychological assessments are often conducted in clinical and research settings to track cognitive changes over single or multiple intervals in patients with Parkinson's disease (PD). Yet few studies have documented test-retest reliability in PD. To address this gap, we used data from the Parkinson's Progression Markers Initiative (PPMI) to investigate the reliability of five well-known neuropsychological tests over a 3-year follow-up assessment in early-stage PD with either normal (PD-NC; N = 158) or abnormal (PD-AC; N = 39) cognitive screening, categorized based on recommended cutoffs for the Montreal Cognitive Assessment (MoCA), and healthy older adults (HOA; N = 102). All participants analyzed maintained the same cognitive status category across the assessment points. Intraclass correlation coefficients (ICCs) estimated reliability. The overall ICCs calculated across time points were as follows: Judgment of Line Orientation (PD-NC = .47, PD-AC = .50, HOA = .59); Letter-Number Sequencing (PD-NC = .64, PD-AC = .64, HOA = .65); Semantic Fluency (PD-NC = .69, PD-AC = .89, HOA = .77); Symbol Digit Modalities Test (PD-NC = .67, PD-AC = .83, HOA = .71). For the two primary components of the Hopkins Verbal Learning Test-Revised, we found the following ICCs: immediate recall (PD-NC = .46, PD-AC = .57, HOA = .58); delayed recall (PD-NC = .42, PD-AC = .57, HOA = .54). Findings from this study provide useful information for clinicians and researchers toward selecting suitable neuropsychological tests to monitor cognition at two or more time points among newly diagnosed individuals with PD and HOA.

Cognitive Functioning of Unaffected First-degree Relatives of Individuals With Late-onset Alzheimer's Disease: A Systematic Literature Review and Meta-analysis

First-degree relatives of individuals with late-onset Alzheimer's disease (LOAD) are at increased risk for developing dementia, yet the associations between family history of LOAD and cognitive dysfunction remain unclear. In this quantitative review, we provide the first meta-analysis on the cognitive profile of unaffected first-degree blood relatives of LOAD-affected individuals compared to controls without a family history of LOAD. A systematic literature search was conducted in PsycINFO, PubMed /MEDLINE, and Scopus. We fitted a three-level structural equation modeling meta-analysis to control for non-independent effect sizes. Heterogeneity and risk of publication bias were also investigated. Thirty-four studies enabled us to estimate 218 effect sizes across several cognitive domains. Overall, first-degree relatives (n = 4,086, mean age = 57.40, SD = 4.71) showed significantly inferior cognitive performance (Hedges' g = -0.16; 95% CI, -0.25 to -0.08; p < .001) compared to controls (n = 2,388, mean age = 58.43, SD = 5.69). Specifically, controls outperformed first-degree relatives in language, visuospatial and verbal long-term memory, executive functions, verbal short-term memory, and verbal IQ. Among the first-degree relatives, APOE ɛ4 carriership was associated with more significant dysfunction in cognition (g = -0.24; 95% CI, -0.38 to -0.11; p < .001) compared to non-carriers (g = -0.14; 95% CI, -0.28 to -0.01; p = .04). Cognitive test type was significantly associated with between-group differences, accounting for 65% (R23 = .6499) of the effect size heterogeneity in the fitted regression model. No evidence of publication bias was found. The current findings provide support for mild but robust cognitive dysfunction in first-degree relatives of LOAD-affected individuals that appears to be moderated by cognitive domain, cognitive test type, and APOE ɛ4.

Commonalities between mind wandering and task-set switching: An event-related potential study

Previous research has established that mind wandering does not necessarily disrupt one's task-switching performance. Here we investigated the effects of mind wandering on electrophysiological signatures, measured using event-related potentials (ERPs), during a switching task. In the current study, a final sample of 22 young adults performed a task-switching paradigm while electroencephalography was continuously recorded; mind wandering was assessed via thought probes at the end of each block. Consistent with previous research, we found no significant disruptive effects of mind wandering on task-switching performance. The ERP results showed that at the posterior electrode sites (P3, Pz, and P4), P3 amplitude was higher for mind-wandering switch trials than on-task switch trials, thus opposing the typical pattern of P3 attenuation during periods of mind wandering relative to on-task episodes. Considering that increased P3 amplitude during higher-order switch trials (e.g., response rule switching) may reflect the implementation of new higher-order task sets/rules, the current findings seem to indicate similar executive control processes underlie mind wandering and task-set switching, providing further evidence in favor of a role for switching in mind wandering.

Neuroinflammation Biomarkers in the AT(N) Framework Across the Alzheimer's Disease Continuum

In the past years, neuroinflammation has been widely investigated in Alzheimer's disease (AD). Evidence from animal, in vivo and post-mortem studies has shown that inflammatory changes are a common feature of the disease, apparently happening in response to amyloid-beta and tau accumulation. Progress in imaging and fluid biomarkers now allows for identifying surrogate markers of neuroinflammation in living individuals, which may offer unprecedented opportunities to better understand AD pathogenesis and progression. In this context, inflammatory mediators and glial proteins (mainly derived from microglial cells and astrocytes) seem to be the most promising biomarkers. Here, we discuss the biological basis of neuroinflammation in AD, revise the proposed neuroinflammation biomarkers, describe what we have learned from anti-inflammatory drug trials, and critically discuss the potential addition of these biomarkers in the AT(N) framework.

Emotional information processing in young and older adults: meta-analysis reveals faces elicit distinct biases

Although a number of empirical studies have found support for distinct emotional information processing biases in young versus older adults, it remains unclear whether these biases are driven by differential processing of positive or negative emotional information (or both) and whether they are moderated by stimulus type, in particular face versus non-face, the former of which is known to be subject to distinct processing. To address these gaps in the literature, our analyses included 2237 younger (mean age = 21.61 years) and 2136 older (mean age = 70.58 years) adults from 73 data sets, 19 involving face stimuli and 54 involving non-face stimuli (objects or scenes). Our findings indicated a significant overall age-related positivity effect (Hedge's g = 0.35) when comparing positive and negative stimuli, but consideration of emotionally neutral stimuli revealed significant age differences in emotional processing for negative stimuli only, with younger adults showing a stronger negativity bias. Furthermore, compared to emotionally neutral stimuli, both younger and older adults showed evidence of biases toward non-face positive and negative stimuli and toward positive but not negative face stimuli. Thus, although the present meta-analysis found evidence of an overall age-related positivity effect consistent with a shift toward positivity with aging, a different picture emerged when comparing emotional against neutral stimuli, and consideration of stimulus type revealed a distinct pattern for face stimuli, which may reflect the biological and social significance of facial expressions.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10433-021-00676-w.

Forward and backward spatial recall in Parkinson's disease and matched controls: A 1-year follow-up study

Patients with Parkinson's disease (PD) exhibit a domain-general visuospatial dysfunction; however, no previous study has examined changes over time in forward and backward spatial recall in PD against controls. To evaluate changes in short-term (STM) and working memory (WM) dysfunction in PD, the current study assessed performance on a computer-modified version of the Corsi Block-Tapping Test (forward and backward recall) at two-time points 1 year apart, while simultaneously exploring associations with potentially relevant demographic and clinical variables. We enrolled 38 patients with PD and 38 controls matched for age, sex, and Montreal Cognitive Assessment (MoCA) total scores. Linear mixed-effects models analyzed the primary measured variables (forward and backward scores). At baseline, the dysfunction effect sizes were as follows: forward recall (-0.45, 95% CI [-0.90, 0.01]) and backward recall (-0.26, 95% CI [-0.71, 0.19]). At follow-up, patients exhibited substantially greater difficulties in backward recall (-0.65, 95% CI [-1.18, -0.13]) compared to the baseline assessment, whereas the forward dysfunction effect size remained almost the same (-0.43, 95% CI [-0.94, 0.09]). Age (p = .005, f = 0.35) and total scores on MoCA (p = .017, f = 0.18), irrespective of group and recall condition, were significant predictors of spatial block scores. The pattern of dysfunction effect sizes indicates that, in contrast to forward recall, backward recall dysfunction in PD worsened 1-year after the baseline assessment, presumably reflecting the progression of PD-related visuospatial WM dysfunction.

Bidirectional within- and between-person relations between physical activity and cognitive function

OBJECTIVES

To examine bidirectional within- and between-person relations between physical activity and cognitive function across 15 years.

METHODS

Participants (N = 1722, age range 40-85 years, 55% women) were drawn from the Betula prospective cohort study. We included four waves of data. Bivariate latent curve models with structured residuals were estimated to examine bidirectional within- and between-person relations between physical activity and cognitive function (episodic memory recall, verbal fluency, visuospatial ability).

RESULTS

We observed no statistically significant bidirectional within-person relations over time. Higher levels of physical activity at baseline were related to less decline in episodic memory recall. Positive occasion-specific within- and between-person relations were observed, with the most consistent being between physical activity and episodic memory recall.

DISCUSSION

The lack of bidirectional within-person relations indicate that shorter time lags may be needed to capture time-ordered within-person relations. The link between higher physical activity at baseline and less decline in episodic memory recall over time may indicate a protective effect of physical activity on episodic memory recall.

Short-Term Retest Performance in Young versus Older Adults: Consideration of Integrated Speed-Accuracy Measures

Objectives: The current research addressed gaps in the literature regarding short-term computerized cognitive retest performance in young and older adults using two integrated speed-accuracy metrics. The aims were: (a) to advance the aging literature on short-term retest performance using a computerized cognitive battery and a retest schedule that included both within- and between-day time points, and (b) to assess the test-retest reliability of two integrated speed-accuracy metrics, inverse efficiency scores (IES) and balanced integration scores (BIS).Method: Twenty young (18-23 years) and thirty older (65-71 years) men completed a battery measuring a range of cognitive functions, six times over three testing days, each 1 week apart.Results: Compared to young adults, older adults exhibited steeper within- and between-day performance gains in IES and BIS, which may reflect a combination of lower initial cognitive ability and familiarity, indicating that older adults may require more familiarization on computerized tests. Relative to unadjusted reaction times, IES reliability appeared comparable in older adults, but slightly lower among young adults. The reliability of BIS was lower than unadjusted reaction times and IES in both age groups.Discussion: Our findings provide guidance for researchers wanting to combine speed and accuracy into a single performance metric in repeated testing contexts.

Non-lactose-fermenting uropathogenic Escherichia coli from dogs: virulence profile characterization

Non-lactose-fermenting Escherichia coli (NLFEC) has a few descriptive studies restricted to human infections. In the present study, isolates of NLFEC obtained from urine samples of dogs with hyperadrenocorticism were characterized regarding their virulence ability, biofilm formation capacity and antimicrobial susceptibility profile. Escherichia coli lactose-fermenting strains from urinary infection in dogs with the same conditions were analysed to provide comparisons. The non-lactose-fermenting E. coli strains were classified as belonging to clade I E. coli, whereas the lactose-fermenting strains were classified in phylogroup B2. All strains presented virulence markers to adhesion, iron acquisition, toxins, colicin and cytotoxin production, and biofilm regulation. Components of the extracellular matrix in addition to the in vitro biofilm formation ability were observed in the strains. Multidrug resistance (MDR) profiles were observed by in vitro susceptibility tests to all NLFEC strains. In summary, non-lactose-fermenting uropathogenic E. coli from dogs behaves similar to lactose-fermenting E. coli, exhibiting MDR profile, and pathogenic potential of promote animal infections.

Accelerometer-based prediction of skeletal mechanical loading during walking in normal weight to severely obese subjects

There is no objective way to monitor mechanical loading characteristics during exercise for bone health improvement. We developed accelerometry-based equations to predict ground reaction force (GRF) and loading rate (LR) in normal weight to severely obese subjects. Equations developed had a high and moderate accuracy for GRF and LR prediction, respectively, thereby representing an accessible way to determine mechanical loading characteristics in clinical settings.

INTRODUCTION

There is no way to objectively prescribe and monitor exercise for bone health improvement in obese patients based on mechanical loading characteristics. We aimed to develop accelerometry-based equations to predict peak ground reaction forces (pGRFs) and peak loading rate (pLR) on normal weight to severely obese subjects.

METHODS

Sixty-four subjects (45 females; 84.6 ± 21.7 kg) walked at different speeds (2-6 km·h^-1) on a force plate-equipped treadmill while wearing accelerometers at lower back and hip. Regression equations were developed to predict pGRF and pLR from accelerometry data. Leave-one-out cross-validation was used to calculate prediction accuracy and Bland-Altman plots. Actual and predicted values at different speeds were compared by repeated measures ANOVA.

RESULTS

Body mass and peak acceleration were included for pGRF prediction and body mass and peak acceleration transient rate for pLR prediction. All pGRF equation coefficients of determination were above 0.89, a good agreement between actual and predicted pGRFs, with a mean absolute percent error (MAPE) below 6.7%. No significant differences were observed between actual and predicted pGRFs at each walking speed. Accuracy indices from our equations were better than previously developed equations for normal weight subjects, namely a MAPE approximately 3 times smaller. All pLR prediction equations presented a lower accuracy compared to those developed to predict pGRF.

CONCLUSION

Walking pGRF and pLR in normal weight to severely obese subjects can be predicted with moderate to high accuracy by accelerometry-based equations, representing an easy and accessible way to determine mechanical loading characteristics in clinical settings.

Physical activity and cognitive function: between-person and within-person associations and moderators

In the present study, we decomposed between- and within-person effects and examined moderators of the longitudinal physical activity-cognition association. Participants (N = 1722) were drawn from the Betula study and we included four waves of data across 15 years. Bayesian multilevel modeling showed that self-reported physical activity did not predict changes in cognitive function. Physical activity positively predicted cognitive performance at baseline, and the relations were stronger for more active (compared to less active) older adults. Physical activity had a positive within-person effect on cognitive function. The within-person effect of physical activity on episodic memory recall was stronger for participants who on average engaged in less physical activity. The within-person effect on verbal fluency was stronger for participants with more education. Our results suggest that preserving cognitive functioning in old age might be more a matter of what you do in old age than reflecting what you did earlier in life.

Correlation of static knee angle in kinematic and radiographic in medial knee osteoarthritis

Introduction The hip-knee-ankle (HKA) angle measured on a full-length weight bearing X-ray made in standing position is considered the gold standard to measure the knee static alignment. However, this method requires special equipment, involves significant radiation exposure and generates extra costs. The 3D motion capture can assess knee angles in a reliable and accurate way.

Objectives This study aimed to analyse the correlation between the HKA angle achieved in full-length X-ray and the in static knee kinematic analysis in patients with medial knee osteoarthritis (OA).

Methodology A descriptive study was design. Anterior-posterior full-limb radiographs were obtained using standard procedures in the same hospital. The HKA angle was measure by an experimental orthopaedic doctor. The kinematics were obtained using Visual3D software after 3D motion capture in two static positions: static comfortable position (Static-1) and a static standard position (Static-2). Kinematic data were filtered (6 Hz) and expressed in degrees (°). The knee joint was created by the distance between the distal end of the thigh and the proximal end of the shank. The angles lower than 180° were considered as varus alignment and those higher than 180° valgus alignment.

Results This study includes 36 patients (22 females; mean age 61,6 ± 8,4; weight 75,8 ± 12,7 kg, and height 161 ± 9,2 cm) with diagnosed medial knee OA Kellgren/Lawrence grade 2 (16 patients) or 3. The patients presented a mean of HKA of 176,2° ± 3,2 in X-ray; 182,1° ± 6,0 in Static-1 and 180,0° ± 5,6 in Static-2. A significant correlation was found between HKA angle and Static-1 (r = 0,525; p = 0,001) and between HKA angle and Static-2 (r = 0,556; p = 0,000).

Conclusion A moderate but significant correlation was found between X-ray and two measure of 3D motion capture in frontal knee angle. Clinically, 3D analysis may help health care professionals in a more practical way to identify the joint angles.

Volunteering in older adulthood is associated with activity engagement and cognitive functioning

Introduction: Given evidence that activity engagement in older adulthood can have protective effects on the aging brain, we investigated the idea that volunteering in the community, which often encompasses social, cognitive, and physical activity, might benefit cognition. Method: Ninety-one retired 65- to 75-year-olds reported their sociodemographic characteristics, wellbeing, volunteering, and activity engagement. They also completed computerized cognitive tests that tapped specific functions known to decline disproportionately with age. Results: Volunteering at least monthly was associated with better working memory and more social and cognitive activity. Mediation analyses indicated that volunteering was indirectly related to switching performance via cognitive activity. However, the volunteering-working memory association did not depend on activity engagement, leaving the underpinning mechanisms unclear. Conclusions: These findings provide new insight into positive associations between older people's volunteering, activity engagement, and cognitive functioning. However, further work is needed to understand the mechanisms that drive volunteering-cognition links, and to establish causality.

218 Urine samples as a noninvasive source of induced pluripotent cells in the swine model

Noninvasive collection of cells used for generation of induced pluripotent stem cells (iPSC) generation would simplify its use for regenerative and reproductive purposes in veterinary medicine, although it is still unpublished in species other than humans. This study aimed to derive urine progenitor cells (UPCs) invitro from urine samples collected from swine, and then to reprogram them into iPSCs. For that, urine samples were collected from three females, and cells were isolated and cultured from each following the human UPCs protocol (Steichen et al. 2017 Curr. Protoc. Hum. Genet. 21, 7.1-21.7.22; https://doi.org/10.1002/cphg.26). Approximately 200mL of urine samples were collected in sterile flasks and centrifuged at 300×g; the pellet was washed in Dulbecco's PBS, resuspended, and cultured in 45% Dulbecco's modified Eagle's medium (DMEM)-high glucose, 5% fetal bovine serum (FBS), 50% Renal Epithelial Cell Growth basal medium (REBM) supplemented with 1% glutamine, 1% nonessential amino acids (NEAA), penicillin/streptomycin (P/S), and REGM supplements hEGF, insulin, hydrocortisone, GA-1000, FBS, transferrin, triiodothyronine, epinephrine (Lonza), and 10ngmL−1 basic fibroblast growth factor (bFGF). The UPCs first colonies were observed approximately 1 week after and resembled epithelial-like cells. At passage 2, one cell line was transduced with murine OCT4, SOX2, KLF4, and C-MYC cDNAs (OSKM) using a lentiviral vector. After 5 days, cells were plated onto mouse embryonic fibroblasts and cultured in knockout DMEM/F12, 20% knockout serum replacement, NEAA, L-glutamine, 2-mercaptoethanol, and P/S supplemented with 10ngmL−1 bFGF. Efficiency of reprogramming was 8.45%, measured by analysing the number of typical iPSC colonies relative to the transduced cells plated, after ~12 days. Three clonal lines (C1, C4, and C6) were maintained invitro and characterised regarding pluripotency markers for at least 30 passages. All three lines were positive for alkaline phosphatase activity in passages 15 and also 22. Immunocytochemistry analysis revealed that C6 (passage 22) was positive for the pluripotency genes OCT4 (1:100, SC), SOX2 (1:500, AB), SSEA1 (1:50, SC), TRA1- 81 (1:50, Millipore), and NANOG (1:100, AB), whereas C1 and C4 (passages 23 and 22, respectively) were positive only for OCT4, SOX2, and SSEA1. The expression of exogenous and endogenous pluripotency factors (OCT4, SOX2, and NANOG) was evaluated by qRT-PCR, comparing the three clonal lines at passages 16/17 and 21/22 and comparing different passages (10, 11, 14, 17, and 22) on C1 line. No statistical difference was observed between cell lines when compared in different passages, perhaps because of the great variation between lines. However, analysis of C1 line over time showed that pluripotency genes increased and exogenous vector expression decreased during early passages (±10 passages); however, after passage 17, OCT4 and NANOG decreased whereas SOX2 and exogenous vector expression increased. In conclusion, it was possible to reprogram UPCs into iPSCs and maintain them in culture for at least 30 passages; however, iPSCS were dependent on exogenous factors. These results represent the partial reprogramming of UPCs to iPSCs in animals for the first time, enabling the generation of invitro disease models using a noninvasive method. Financial support for this study was received from FAPESP (2019/02811-2, 2015/26818-5), CNPq (433133/2018-0), and CAPES.

Effects of a Brief Stair-Climbing Intervention on Cognitive Performance and Mood States in Healthy Young Adults

OBJECTIVE

Previous studies focused on the benefits of acute exercise on cognition and mood have mostly used specialized laboratory-based equipment, thus little is known about how such protocols generalize to naturalistic settings. Stair climbing is a simple and readily accessible means of exercise that can be performed in naturalistic settings (e.g., at home or at the workplace). In the present study we examined the effects of stair-climbing intervals on subsequent cognitive performance and mood in healthy young adults.

METHOD

Thirty-two undergraduate students (M age = 19.4 years, SD = 1.3; 21 females) completed a controlled randomized crossover trial with session order counterbalanced across participants. Participants visited the lab on two occasions, one week apart, and completed one control session (no exercise) and one stair-climbing session (3 × 1 min stair-climbing intervals) with cognitive performance and mood assessed at the end of each session.

RESULTS

Repeated measures ANCOVA revealed that males (Hedges' g av = 0.45) showed better switching performance following the stair climbing but females (Hedges' g av < 0.03) did not. Participants felt more energetic (Hedges' g av = 1.05), less tense (Hedges' g av = 0.61), and less tired (Hedges' g av = 0.43) following the stair climbing. In addition, higher exercise intensity during the stair climbing predicted better subsequent switching performance and higher energetic ratings.

CONCLUSION

These findings indicate that short bouts of stair climbing in a naturalistic setting can induce cognitive benefits for more challenging tasks, albeit only in males, indicating a sex-specific effect. Short bouts of stair climbing can be a practical approach to increase feelings of energy in daily life.

Cerebrovascular regulation is not blunted during mental stress

NEW FINDINGS

What is the central question of the study? What are the effects of acute mental stress on the mechanisms regulating cerebral blood flow? What is the main finding and its importance? The major new findings are as follows: (i) high mental stress and hypercapnia had an interactive effect on mean middle cerebral artery blood velocity; (ii) high mental stress altered the regulation of cerebral blood flow; (iii) the increased cerebrovascular hypercapnic reactivity was not driven by changes in mean arterial pressure alone; and (iv) this increased perfusion with mental stress appeared not to be justified functionally by an increase in oxygen demand (as determined by near-infrared spectroscopy-derived measures).

ABSTRACT

In this study, we examined the effects of acute mental stress on cerebrovascular function. Sixteen participants (aged 23 ± 4 years; five female) were exposed to low and high mental stress using simple arithmetic (counting backwards from 1000) and more complex arithmetic (serial subtraction of 13 from a rapidly changing four-digit number), respectively. During consecutive conditions of baseline, low stress and high stress, end-tidal partial pressure of CO₂ ( P ET , C O 2 ) was recorded at normocapnia (37 ± 3 mmHg) and clamped at two elevated levels (P < 0.01): 41 ± 1 and 46 ± 1 mmHg. Mean right middle cerebral artery blood velocity (MCAv_mean ; transcranial Doppler ultrasound), right prefrontal cortex haemodynamics (near-infrared spectroscopy) and mean arterial blood pressure (MAP; finger photoplethysmography) were measured continuously. Cerebrovascular hypercapnic reactivity (ΔMCAv_mean /Δ P ET , C O 2 ), cerebrovascular conductance (CVC; MCAv_mean /MAP), CVC CO₂ reactivity (ΔCVC/Δ P ET , C O 2 ) and total peripheral resistance (MAP/cardiac output) were calculated. Acute high mental stress increased MCAv_mean by 7 ± 7%, and more so at higher P ET , C O 2 (32 ± 10%; interaction, P = 0.03), illustrating increased sensitivity to CO₂ (i.e. its major regulator). High mental stress also increased MAP (17 ± 9%; P ≤ 0.01), coinciding with increased near-infrared spectroscopy-derived prefrontal haemoglobin volume and saturation measures. High mental stress elevated both cerebrovascular hypercapnic and conductance reactivities (main effect of stress, P ≤ 0.04). These findings indicate that the cerebrovascular response to acute high mental stress results in a coordinated regulation between multiple processes.

Swimming-related effects on cerebrovascular and cognitive function

Both acute and regular exercise influence vascular and cognitive function. Upright aquatic exercise increases mean middle cerebral artery blood velocity (MCAvmean ) and has been suggested as favorable for cerebrovascular adaptations. However, MCAvmean has not been reported during swimming. Thus, we examined the cerebrovascular and cognitive effects of swimming. Ten land-based athletes (22 ± 5 years) and eight swimmers (19 ± 1 years) completed three cognitive tasks and four conditions that were used to independently and collectively delineate the swimming-related factors (i.e., posture, immersion, CO2 retention [end-tidal CO2 ; PETCO2 ], and motor involvement). Measurements of MCAvmean and PETCO2 were taken throughout each condition. Prone posture increased MCAvmean by 11% (P < 0.01 vs. upright land). Water immersion independently increased MCAvmean when upright (12%; P < 0.01) but not prone (P = 0.76). The consequent rise in PETCO2 during head-out, breast-stroke swimming (50% heart rate range) independently increased MCAvmean by 14% (P < 0.01), while the motor involvement of swimming per se did not significantly change MCAvmean (P = 0.32). While accounting for sex, swimmers had ~17% lower MCAvmean during all rest conditions (P ≤ 0.05). However, in a subset of participants, both groups had similar internal carotid artery diameters (P = 0.99) and velocities (P = 0.97). Water immersion per se did not alter cognition (P ≥ 0.15), but 20 min of moderate-intensity swimming improved visuomotor performance by 4% (P = 0.03), regardless of athlete group (P = 0.12). In conclusion, breast-stroke swimming increased MCAvmean mostly due to postural and PETCO2 effects, with minimal contributions from water immersion or motor activity. Lastly, swimming improved cognitive functioning acutely, regardless of athlete group. Future research should explore the chronic effects of swimming on cerebrovascular function and cognition, particularly in aging.

Volunteering in the Community: Potential Benefits for Cognitive Aging

Objectives

This review aims to advance understanding of the potential benefits of volunteering in the community for older adults' cognitive functioning by taking an in-depth look at the relevant evidence to date.

Method

This review describes the main pathways through which volunteering could plausibly benefit cognitive functioning and critically examines research that has specifically investigated links between volunteering and cognition. Fifteen articles that assessed in adults aged ≥ 55 years the relationship between volunteering (predictor) and cognitive functioning (outcome) were identified via literature database searches.

Results

On balance, evidence from the small number of relevant studies to date supports the idea that volunteering can protect against cognitive aging with respect to global functioning and at least some specific cognitive domains. Studies that used robust designs and assessed domain-specific cognitive functioning produced the largest effect sizes.

Discussion

To help advance the field, this review puts forward recommendations for future research, with an emphasis on the need for robust study designs and specific investigations into the nature and extent of the cognitive benefits of volunteering. Through that work, researchers can determine how a simple and accessible activity like volunteering can best be used to help reduce the burden of age-related cognitive decline.

A meta-analysis on verbal working memory in children and adolescents with ADHD

Objective: Previous meta-analyses have demonstrated verbal working memory (WM) dysfunction in children and adolescents with attention deficit/hyperactivity disorder (ADHD); however, the findings are inconsistent. The main objective of this meta-analysis was to investigate the performance of children and adolescents with ADHD in the Digit Span Backwards (DSB) subtest from the Wechsler Intelligence Scale for Children or Wechsler Adult Intelligence Scale. We also sought to provide an updated meta-analysis on WM in children and adolescents with ADHD.Method: PubMed, PsyINFO, Scopus, and Web of Science were searched to locate studies published between 1990 and 2016 that report DSB scores both of children and adolescents with ADHD and matched controls. Potential moderator variables were also analyzed.Results: Forty-nine studies comparing children and adolescents with ADHD (n = 4956) against healthy controls (n = 3249) generated a medium-sized effect (Hedges' g) of 0.56 (95% CI [0.49, 0.64]), indicating poorer verbal WM performance in those with ADHD. A subgroup meta-analysis of studies with participants aged 8-16 years only demonstrated low heterogeneity (I² = 17.06, cf. 55.50 for the main analysis). Moreover, the meta-regression showed a negative association (β = -.05, p = .02) between DSB performance differences and increasing age, indicating that for every one year increase in age the effect size decreased by .05.Conclusion: These results, which emanated from the largest meta-analysis concerning verbal WM in ADHD reported to date, reinforce WM as a key domain of cognitive dysfunction in ADHD, and point to age as the main variable influencing DSB performance difficulties.

Investigating links between habitual physical activity, cerebrovascular function, and cognitive control in healthy older adults

A growing body of evidence indicates regular physical activity benefits older adults' cognitive functioning, particularly when a high level of cognitive control is required. Recent research has pointed to improved cerebrovascular function as one mechanism through which such benefits might arise. This study built on previous research by investigating in 51 healthy older adults aged 60-72 years relationships between habitual physical activity, cerebrovascular function (indicated by resting cerebral blood flow velocity in the middle cerebral artery [n = 42], and its responsiveness to hypercapnia [n = 26] and hypocapnia [n = 25]), and cognitive control (inhibition and switching). Linear regression analyses showed moderate positive associations between physical activity and inhibitory control, but not cerebrovascular function. There were also no significant relationships between the cerebrovascular measures and cognitive control. These results indicate that regular engagement in physical activity is associated with superior inhibitory control in older adulthood, but cerebrovascular function was not found to explain those relationships. Taken together, the current findings reinforce reports of positive links between habitual physical activity and cognition in healthy older adults, but also signal that interrelationships with cerebrovascular function may be more complex than currently indicated by the literature, necessitating further research to elucidate the role cerebrovascular function might play in accounting for physical activity-cognition links in healthy older adults.

Evidence Transcranial Direct Current Stimulation Can Improve Saccadic Eye Movement Control in Older Adults

Objectives: Ageing is associated with declines in voluntary eye movement control, which negatively impact the performance of daily activities. Therapies treating saccadic eye movement control deficits are currently lacking. To address the need for an effective therapy to treat age-related deficits in saccadic eye movement control, the current study investigated whether saccadic behaviour in older adults can be improved by anodal transcranial direct current stimulation (tDCS) over the dorsolateral prefrontal cortex using a montage that has been proven to be effective at improving nonoculomotor control functions. Method: The tDCS protocol entailed a 5 cm × 7 cm anodal electrode and an encephalic cathodal reference electrode positioned over the contralateral supraorbital area. In two experiments, healthy older men completed one active (1.5 mA current for 10 min) and one sham stimulation session, with the session order counterbalanced across participants, and eye movement testing following stimulation. In the first experiment, participants rested during the tDCS (offline), whereas in the follow-up experiment, participants engaged in antisaccades during the tDCS (online). Results: Analyses revealed improvements in saccadic performance following active anodal tDCS relative to sham stimulation in the online experiment, but not in the offline experiment, which was presumably due to the activation of the relevant networks during tDCS promoting more targeted effects. Discussion: These outcomes converge with findings pertaining to nonoculomotor cognitive functions, and provide evidence that tDCS can improve saccadic eye movement control in older adults.

Computerized testing in Parkinson's disease: Performance deficits in relation to standard clinical measures

OBJECTIVE

This study assessed deficits associated with Parkinson's disease (PD) at two time points separated by 1 year using a computerized neuropsychological battery, and determined interrelationships with conventional clinical measures of cognitive functioning (Montreal Cognitive Assessment; MoCA) and motor impairment (Part III of the Unified PD Rating Scale; UPDRS), as well as other factors known to influence cognitive dysfunction in PD.

METHOD

Participants included 37 with PD and 47 controls. Linear mixed-effects models were developed for each computerized task.

RESULTS

Results showed that the PD group performed worse than controls on all of the computerized tasks at both time points. In contrast, MoCA scores differed between PD and controls only at follow-up. However, the MoCA detected decline over the year in the PD group, whereas only one of the computerized tasks did. In both groups, higher MoCA scores predicted better performance on some but not all of the computerized tasks. Surprisingly, UPDRS-rated motor impairment did not predict performance on any of the computerized tasks, and aside from older age, which predicted poorer performance on all but one task, the other factors-education, affective and impulsivecompulsive symptoms, sleep quality, dopaminergic medication-generally had no relationship with performance on the computerized tasks.

CONCLUSIONS

The presence of performance deficits for all of the computerized tasks in the PD group compared to controls, but not for the MoCA at initial testing, indicates that the computerized battery was better able to detect deficits. However, in contrast to the MoCA, the current results call into question the suitability of the computerized battery as measured here for tracking decline.

Effects of Unilateral Distractors: A Comparison of Eye Movement and Key Press Responses

We compared the effects of a unilateral distractor on the latencies of voluntary eye movements and key press responses in order to elucidate some of the differences between these two types of response with respect to processing distractors. On each trial, participants indicated the colour of a central patch by making a left or a right response. The colour of the distractor either matched the target colour or matched the colour associated with the incorrect response. Similarly, the side of the distractor corresponded to the side of either the correct or the incorrect response. The results showed that side congruency exerted a main effect only on eye movement responses, but colour congruency affected eye movement and key press responses similarly. Moreover, when we made the target more distinct from the distractor, only distractors that appeared on the same side as the response elicited a colour congruency effect, for both response modalities. Wepropose that (1) the appearance of the distractor activates oculomotor cells, which facilitate a subsequent eye movement with the same direction vector, (2) the distinctiveness of the target determines whether colour and side congruency interact, and (3) spatial codes mediate the interaction between colour and side congruency that occurs when the target is sufficiently distinct from the distractor.

Inhibition of Return Generated by Voluntary Saccades is Independent of Attentional Momentum

Summoning attention to a peripheral location, either by a peripheral cue with the eyes fixed or when a voluntary saccade is made to it and gaze is then returned to the centre, delays detection of subsequent targets at that location compared to a location in the opposite visual field. It has been proposed that oculomotor activation generates this inhibition of return (IOR). This account presupposes that the asymmetry in detection results from inhibition at the cued location rather than facilitation at the uncued location. This has been confirmed for exogenously generated IOR. However, it has not, heretofore, been confirmed for “IOR” generated by voluntary saccades. The current study investigated whether the asymmetry in target detection, elicited either by a peripheral flash or by an eye movement generated in response to a central arrowhead, reflects facilitation at the opposite location due to the path of attentional momentum. Reaction times at the cued location were slower than reaction times at the opposite or perpendicular locations, which did not differ. Opposite facilitation due to attentional momentum requires that opposite be faster than perpendicular, which was not obtained. The results were the same whether IOR was generated by an exogenous cue or by a saccade executed endogenously to a central arrow.

Developing clinically practical transcranial direct current stimulation protocols to improve saccadic eye movement control

Recent research indicates that anodal transcranial direct current stimulation (tDCS) applied over the frontal eye field (FEF) can improve saccadic eye movement control in healthy young adults. The current research set out to determine whether similar results can be produced using a clinically practical protocol, whether tDCS applied over the dorsolateral prefrontal cortex (DLPFC) might also afford benefits, and whether benefits extend to older adults. Twenty young and 10 older adults completed two active (FEF and DLPFC) and one sham stimulation session. To aid clinical translation, the method of positioning the electrodes entailed simple measurements only. Saccadic performance following anodal tDCS applied over the FEF or DLPFC did not differ from the sham condition in either age group. Additionally, saccadic performance contralateral to the active electrodes showed no evidence of benefits over ipsilateral performance. These results call into question whether the protocol utilized can be applied effectively using only simple measurements to localize the relevant frontal subregion. Future efforts to develop a clinically practical tDCS protocol to improve saccadic eye movement control should include a sham control condition and consider adjusting the tDCS electrode montage and current strength to optimize the chances of conferring benefits in the population under study.

Testing the Validity of Taxonic Schizotypy Using Genetic and Environmental Risk Variables

BACKGROUND

Meehl regarded schizotypy as a categorial liability for schizophrenia that is the product of genes, environment, and gene-environment interactions. We sought to test whether schizophrenia-related genotypes and environmental risk factors predict membership in classes defined by taxometric analyses of positive (cognitive-perceptual), negative (interpersonal), and disorganized schizotypy.

METHODS

Participants (n = 500) completed the Schizotypal Personality Questionnaire (SPQ) and provided information on the following risk factors: cannabis use, pregnancy and obstetric complications, social adjustment, and family history of psychosis. Saliva samples were obtained so that the frequency of single-nucleotide polymorphism (SNP) alleles associated with risk for developing schizophrenia could be determined. Genotyped SNPs were rs1625579 (MIR137), rs7004633 (MMP16), rs7914558 (CNNM2), and rs12966547 (CCDC68). Sets of SPQ items were subject to multiple coherent cut kinetic (CCK) analyses, including mean-above-minus-below-a-cut, maximum covariance, maximum eigenvalue, and latent modes analyses.

RESULTS

CCK analyses indicated latent taxonicity of schizotypy across the 3 item sets. The cognitive-perceptual class had a base rate of 25%, and membership was predicted by the rs7004633 SNP (odds ratio = 2.33, 95% confidence interval = 1.15-4.72 in adjusted analyses). Poor social adjustment predicted memberships in the interpersonal (16%) and disorganized (21%) classes. Classes were found not to be mutually exclusive.

CONCLUSIONS

Schizotypy is taxonic and schizotypy class membership is predicted by genetic and environmental factors that predict schizophrenia. The findings hold the promise that a more complete understanding of schizotypy as a schizophrenia liability state will come from investigation of other genes and environmental factors associated with schizophrenia.

Physicians versus surgeons. A pilot study on hand dexterity within a controlled population

INTRODUCTION

Hand dexterity is defined as the innate or acquired capacity of performing any given procedure with one's hands. This study seeks the role of regular hand training on hand dexterity over time. Materials and Methods : Pilot study composed by two independent groups with 28 subjects each (surgeons and physicians), stratified according to gender and age. Measurement of hand dexterity using Lafayette's Purdue Pegboard through the sum of the first three exercises as well as the assembly exercise. No difference was found between groups in regards of gender, age, time of practice and hand size (p = 0.415 ; p = 0.225 ; p = 0.267 ; p = 0.937). Statistical significance was assumed when p < 0.050.

RESULTS

Surgeons performed better but a statistically significant difference was not observed both on the -assembly score (p = 0.560) and three tests sum score (p = 0.244). The decay of dexterity over time happened in a homogeneous fashion in the surgeons' arm (p < 0.001 and p = 0.043) but not in the physicians' arm (p = 0.157 and p = 0.098).

DISCUSSION

Surgeons seem to perform better than physicians in regards of hand dexterity, although no definitive conclusion was possible given our small sample. It is well known that aging worsens hand -dexterity, but our study suggests it happens much more homogeneously within surgeons.

Effects of low dose ibogaine on subjective mood state and psychological performance

ETHNOPHARMACOLOGICAL RELEVANCE

Root bark from Tabernanthe iboga has been used traditionally in West Africa as a psychoactive substance in religious rituals. In smaller doses it is reported anecdotally to have stimulant properties.

AIM OF THE STUDY

To evaluate the influence of a single 20mg ibogaine dose on psychological variables reflecting subjective mood state and a range of cognitive functions.

MATERIALS AND METHODS

21 healthy male volunteers received single 20mg doses of ibogaine after 6 days pretreatment with double-blind paroxetine or placebo. We compared responses to a battery of psychometric tests and subjective mood ratings performed before and 2h after ibogaine dosing, and assessed relationships between changes in test scores and concentrations of active moiety (the sum of molar noribogaine and ibogaine concentrations). Psychological tests were chosen based on responsiveness to opioid and serotonergic ligands.

RESULTS

Ibogaine had minimal influence on psychological tests and mood ratings. The ability to selectively ignore distracting spatial information showed some evidence of modulation; however because this effect was limited to the less challenging condition calls into question the reliability of this result.

CONCLUSION

We were unable to identify stimulant effects after single 20mg doses of ibogaine. Future research is needed to confirm whether active moiety concentrations impact selective attention abilities while leaving other cognitive functions and mood state unaffected.

Cognitive Difficulty Intensifies Age-related Changes in Anterior Frontal Hemodynamics: Novel Evidence from Near-infrared Spectroscopy

Alongside age-related brain deterioration, cognitive functioning declines, particularly for more demanding tasks. Past research indicates that, to offset this decline, older adults exhibit hemodynamic changes consistent with recruitment of more anterior brain regions. However, the nature of the hemodynamic changes remains unclear. To address this knowledge gap, we used near-infrared spectroscopy in 36 young adults (aged 18-30 years) and 36 older adults (aged 60-72 years) to assess anterior frontal hemodynamic responses to engagement in three cognitive tasks of increasing difficulty. Behavioral results for all three tasks confirmed aging deficits (evidenced by slower reaction times and reduced accuracy rates) that progressively increased with task difficulty. Hemodynamic results showed opposing effects in young versus older adults, with oxygenated and total hemoglobin decreasing in young but increasing in older adults, particularly during the harder tasks. Also, tissue oxygenation increased only in older adults during the harder tasks. Among the older adults only, anterior frontal hemodynamic changes correlated with better cognitive performance, indicating that they were compensatory in nature. These findings provide novel evidence of age-related anterior frontal hemodynamic changes that intensify with cognitive demands and compensate for performance deficits.

Alemtuzumab induction and antibody-mediated rejection in kidney transplantation

BACKGROUND

Induction therapy improves graft outcomes in kidney transplant recipients (KTRs). We aimed to compare the incidences of antibody-mediated rejection (AMR) and acute cellular rejection (ACR) as well as graft and patient outcomes in KTRs who underwent induction with alemtuzumab versus rabbit-antithymocyte globulin (r-ATG).

METHODS

This was a single-center retrospective study involving patients who underwent kidney transplantation between January 2009 and December 2011 after receiving induction therapy with either alemtuzumab or r-ATG. Maintenance immunosuppression included tacrolimus and mycophenolate mofetil with early steroid withdrawal. Acute rejection was diagnosed using allograft biopsy.

RESULTS

Among the 108 study patients, 68 received alemtuzumab and 40 got r-ATG. There was a significantly higher incidence of AMR (15% vs 2.5%; P = .008) and similar incidence of ACR (4.4% vs 10%; P = .69) for alemtuzumab versus r-ATG groups. One-year serum creatinine levels (l.68 ± 0.8 mg/dL vs 1.79 ± 1.8 mg/dL; P = .66) as well as graft (91.1 ± 3.5% vs 94.5 ± 3.8%; P = .48) and patient (93.8 ± 3.0% vs 96.4 ± 3.5%; P = .92) survivals were similar for the alemtuzumab versus the r-ATG groups.

CONCLUSION

Our study showed a higher incidence of AMR and similar incidence of ACR in KTRs who underwent induction with alemtuzumab compared with those who received r-ATG and were maintained on tacrolimus and MMF. This was despite a lower HLA mismatch in the alemtuzumab group. One-year graft survival, patient survival, and allograft function were similar. Inadequate B-cell suppression by alemtuzumab as well as altered phenotypic and functional properties of repopulating B cells could be contributing to heightened risk of AMR in these patients.

Piometra em uma leoa (Panthera leo): relato de caso

A piometra é uma infecção aguda ou crônica do útero que ocorre frequentemente em cadelas não castradas, podendo também ocorrer em gatas domésticas e selvagens, sendo poucos os estudos relacionados à piometra em grandes felídeos. O objetivo deste relato foi descrever um caso de piometra em uma leoa (Panthera leo) de cativeiro, as lesões de necropsia e histológicas, bem como os resultados da análise microbiológica. Uma leoa com aproximadamente 23 anos, pertencente a um criadouro conservacionista de Santa Maria-RS, foi encontrada morta pela manhã em seu recinto. Após coleta de dados, procedeu-se à necropsia e à coleta de material para análise histopatológica e bacteriológica. A análise microbiológica revelou predomínio das bactérias Streptococcus sp. e Escherichia coli no conteúdo purulento do útero, caracterizando como piometra, e a bactéria predominante em plasma, fígado e medula óssea foi E. coli. De acordo com o laudo histopatológico, as alterações observadas nessa leoa sugerem um quadro de septicemia grave, sendo a origem do foco infeccioso bacteriano, provavelmente, a piometra. Considera-se importante chamar a atenção dos médicos veterinários de animais selvagens para um diagnóstico precoce dessa doença, que é comum em cadelas, mas que pode acometer também felídeos selvagens e levá-los à morte.

Computational fluid dynamics vs. inverse dynamics methods to determine passive drag in two breaststroke glide positions

Computational fluid dynamics (CFD) plays an important role to quantify, understand and "observe" the water movements around the human body and its effects on drag (D). We aimed to investigate the flow effects around the swimmer and to compare the drag and drag coefficient (CD) values obtained from experiments (using cable velocimetry in a swimming pool) with those of CFD simulations for the two ventral gliding positions assumed during the breaststroke underwater cycle (with shoulders flexed and upper limbs extended above the head-GP1; with shoulders in neutral position and upper limbs extended along the trunk-GP2). Six well-trained breaststroke male swimmers (with reasonable homogeneity of body characteristics) participated in the experimental tests; afterwards a 3D swimmer model was created to fit within the limits of the sample body size profile. The standard k-ε turbulent model was used to simulate the fluid flow around the swimmer model. Velocity ranged from 1.30 to 1.70 m/s for GP1 and 1.10 to 1.50 m/s for GP2. Values found for GP1 and GP2 were lower for CFD than experimental ones. Nevertheless, both CFD and experimental drag/drag coefficient values displayed a tendency to jointly increase/decrease with velocity, except for GP2 CD where CFD and experimental values display opposite tendencies. Results suggest that CFD values obtained by single model approaches should be considered with caution due to small body shape and dimension differences to real swimmers. For better accuracy of CFD studies, realistic individual 3D models of swimmers are required, and specific kinematics respected.