Differences In Age-related Changes Research Articles

Age-related changes in hand dominance and functional asymmetry in older adults.

The aim of the study was to investigate fine motor performance and ascertain age-related changes in laterality between the dominant and non-dominant hand. A representative sample of 635 adults (144 males and 491 females) aged 50 years and over completed a test battery MLS (Motor Performance Series) to assess a broad range of hand functions. Functional asymmetry was observed in all four motor tests (postural tremor, aiming, tapping, and inserting long pins). Significant differences between the dominant and non-dominant hand were obtained in both sexes across all age groups, except in the oldest female group (age >70) for the aiming (number of hits and errors) and postural tremor (number of errors) tasks. These differences in age-related changes may be attributed to hemispheric asymmetry, environmental factors, or use-dependent plasticity. Conflicting evidence in the literature warrants additional research to better explain age-related alterations of hand dominance and manual performance in old age.

Abstract 34: Cardiorespiratory Fitness Response to Short Term Supervised Exercise Training Predicts Age Related Cardiorespiratory Fitness Decline Over Long Term Follow up

Introduction: Substantial heterogeneity exists in the cardiorespiratory fitness (CRF) change response to short-term supervised exercise training and its long-term prognostic implication is not well understood. Here, we evaluated the association between the short-term training related changes in CRF and CRF levels 10 years later. Methods: STRRIDE trial participants that were originally randomized to exercise training for 8 months and participated in the 10-year follow up visit were included. CRF levels were measured at baseline, post-training (8 months), and 10-year follow-up as peak oxygen uptake (VO 2 , ml/kg/min) using the maximal treadmill test. Participants were stratified into low, moderate, and high CRF response (CRF-R) groups according to the training-regimen specific tertiles of CRF change from baseline to post-training. Adjusted linear regression models were used to determine the association between short-term change in CRF with training and CRF levels at 10-year follow-up. Results: The study included 80 participants (age = 52 years, 35% women). There was no significant difference in the baseline characteristics of the CRF-R groups. At 10-year follow-up, high CRF-R group had the lowest decline in CRF compared with moderate or low CRF-R groups (-0.005 vs. -2.6. vs. -3.6 ml/kg/min, p = 0.009, Figure). This was largely related to the differential age-related changes in peak oxygen pulse across the three groups (0.58 vs. -0.23 vs. -0.86 ml/beat, p = 0.02) with no difference in the peak heart rate change. In adjusted analysis, high CRF-R was significantly associated with higher CRF levels at follow-up independent of the exercise intervention and other baseline characteristics [High vs. Low (ref) CRF-R: Std β = 0.25; p = 0.004] Conclusion: CRF change in response to short-term training is a significant predictor of age-related CRF decline over long-term follow-up. Thus, training responsiveness may identify individuals at risk for exaggerated CRF decline with aging and associated incidence of cardiovascular diseases.

The Effects of Age, from Young to Middle Adulthood, and Gender on Resting State Functional Connectivity of the Dopaminergic Midbrain.

Dysfunction of the dopaminergic ventral tegmental area (VTA) and substantia nigra pars compacta (SNc) is implicated in psychiatric disorders including attention-deficit/ hyperactivity disorder (ADHD), addiction, schizophrenia and movement disorders such as Parkinson’s disease (PD). Although the prevalence of these disorders varies by age and sex, the underlying neural mechanism is not well understood. The objective of this study was to delineate the distinct resting state functional connectivity (rsFC) of the VTA and SNc and examine the effects of age, from young to middle-adulthood, and sex on the rsFC of these two dopaminergic structures in a data set of 250 healthy adults (18–49 years of age, 104 men). Using blood oxygenation level dependent (BOLD) signals, we correlated the time course of the VTA and SNc to the time courses of all other brain voxels. At a corrected threshold, paired t-test showed stronger VTA connectivity to bilateral angular gyrus and superior/middle and orbital frontal regions and stronger SNc connectivity to the insula, thalamus, parahippocampal gyrus (PHG) and amygdala. Compared to women, men showed a stronger VTA/SNc connectivity to the left posterior orbital gyrus. In linear regressions, men but not women showed age-related changes in VTA/SNc connectivity to a number of cortical and cerebellar regions. Supporting shared but also distinct cerebral rsFC of the VTA and SNc and gender differences in age-related changes from young and middle adulthood in VTA/SNc connectivity, these new findings help advance our understanding of the neural bases of many neuropsychiatric illnesses that implicate the dopaminergic systems.

Eyelid fissure dimensions in Japanese and in Brazilians of European descent over 50 years of age.

To investigate differences in the palpebral fissure eyelid position in Japanese subjects and in Brazilian subjects of European descent over 50 years of age. A cross-sectional study evaluating 50 Japanese subjects and 50 Bra---zilian subjects of European descent over 50 years of age was performed to evaluate the effect of aging on eyelid position. Digital photographs were taken with the eyes in the primary position and transferred to a computer to be processed by Scion imaging software for evaluation of palpebral fissure width, height, and margin reflex distance (MRD). The data were statistically analyzed according to sex, age, and race. The width of the eyelid fissure in Japanese subjects was higher than that in Brazilian subjects, whereas the height of the eyelid fissure and the MRD1 was higher in Brazilians than in Japanese (p<0.01). Width, height, and MRD1 were linearly associated with age only in the Japanese group (p<0.05); this association was observed only with width in the Brazilian group (p<0.05). There were no differences according to laterality in either group (p>0.05). There are racial differences in age-related changes in the eyelids, which are more marked in Japanese subjects.

Functional connectivity differences in autism during face and car recognition: underconnectivity and atypical age-related changes.

Face recognition abilities improve between adolescence and adulthood over typical development (TD), but plateau in autism, leading to increasing face recognition deficits in autism later in life. Developmental differences between autism and TD may reflect changes between neural systems involved in the development of face encoding and recognition. Here, we focused on whole-brain connectivity with the fusiform face area (FFA), a well-established face-preferential brain region. Older children, adolescents, and adults with and without autism completed the Cambridge Face Memory Test, and a matched car memory test, during fMRI scanning. We then examined task-based functional connectivity between the FFA and the rest of the brain, comparing autism and TD groups during encoding and recognition of face and car stimuli. The autism group exhibited underconnectivity, relative to the TD group, between the FFA and frontal and primary visual cortices, independent of age. Underconnectivity with the medial and rostral lateral prefrontal cortex was face-specific during encoding and recognition, respectively. Conversely, underconnectivity with the L orbitofrontal cortex was evident for both face and car encoding. Atypical age-related changes in connectivity emerged between the FFA and the R temporoparietal junction, and R dorsal striatum for face stimuli only. Similar differences in age-related changes in autism emerged for FFA connectivity with the amygdala across both face and car recognition. Thus, underconnectivity and atypical development of functional connectivity may lead to a less optimal face-processing network in the context of increasing general and social cognitive deficits in autism.

Differential age-related changes in localizing a target among distractors across an extended visual field.

Age differences in the spatial distribution of attention over a wide field of view have only been described in terms of the spatial extent, leaving the topographical aspect unexplored. This study examined age differences between younger and older adults in good general health in an important topographical characteristic, the asymmetry between the upper and lower visual fields. In Experiment 1, we found age differences across the entire attentional visual field. In addition, age differences were greater in the upper compared to the lower field. In Experiment 2, we examined whether the finding of a greater age difference in the ability to localize a target among distractors in the upper visual field in Experiment 1 was a result of possible differential age differences between the upper and lower visual fields in the ability to localize a target even when there was no distractor competing for attention. Our results suggested that the age differences we observed were linked to age differences in the ability to filter out distractors that compete with the target for attention rather than the ability to process only the target over a wide field of view. While younger adults demonstrated an upper visual field advantage in the ability to localize a target among distractors, there was no such field advantage in older adults. We discuss this finding of diminished upper visual field advantage in older adults in light of an account of pervasive loss of neural specialization with age. We postulate that one possible explanation of age differences in the asymmetry between the upper and lower visual fields may be an adaptation to age-related physical decline. We also discuss important implications of our findings in risks of falls and vehicle crashes.

Acute central effects of corticotropin-releasing factor (CRF) on energy balance: Effects of age and gender

Previously demonstrated age-related changes in the catabolic melanocortin system that may contribute to middle-aged obesity and aging anorexia, raise the question of the potential involvement of corticotropin-releasing factor (CRF) in these phenomena, as this catabolic hypothalamic mediator acts downstream to melanocortins. Catabolic effects of CRF were shown to be mediated by both CRF1 (hypermetabolism) and CRF2 (anorexia) receptors. To test the potential role of CRF in age-related obesity and aging anorexia, we investigated acute central effects of the peptide on energy balance in male and female rats during the course of aging.Effects of an intracerebroventricular CRF injection on food intake (FI), oxygen-consumption (VO2), core- and tail skin temperatures (Tc and Ts) were studied in male and female Wistar rats of five different age-groups (from 3- to 24-month). Anorexigenic responsiveness was tested during 180-min re-feeding (FeedScale) following 24-h fasting. Thermoregulatory analysis was performed by indirect calorimetry (Oxymax) complemented by thermocouples recording Tc and Ts (indicating heat loss).CRF suppressed FI in 3-month male and female animals. In males, CRF-induced anorexia declined with aging, whereas in females it was maintained in all groups. The peptide increased VO2 and Tc in all male age-groups, while the weaker hypermetabolic response characterizing 3-month females declined rapidly with aging.Thus, age-related alterations in acute central anorexigenic and hypermetabolic effects of CRF show different non-parallel patterns in males and females. Our findings underline the importance of gender differences. They also call the attention to the differential age-related changes in the CRF1 and CRF2 receptor systems.

Impaired Frontal-Limbic White Matter Maturation in Children at Risk for Major Depression.

Depression is among the most common neuropsychiatric disorders. It remains unclear whether brain abnormalities associated with depression reflect the pathological state of the disease or neurobiological traits predisposing individuals to depression. Parental history of depression is a risk factor that more than triples the risk of depression. We compared white matter (WM) microstructure cross-sectionally in 40 children ages 8-14 with versus without parental history of depression (At-Risk vs. Control). There were significant differences in age-related changes of fractional anisotropy (FA) between the groups, localized in the anterior fronto-limbic WM pathways, including the anterior cingulum and the genu of the corpus callosum. Control children exhibited typical increasing FA with age, whereas At-Risk children exhibited atypical decreasing FA with age in these fronto-limbic regions. Furthermore, dorsal cingulate FA significantly correlated with depressive symptoms for At-Risk children. The results suggest maturational WM microstructure differences in mood-regulatory neurocircuitry that may contribute to neurodevelopmental risk for depression. The study provides new insights into neurodevelopmental susceptibility to depression and related disabilities that may promote early preventive intervention approaches.

Difference in age-related changes in surface electromyogram of tibialis anterior and triceps surae

We have investigated the dissimilarity between age-associated changes of surface electromyogram (sEMG) of tibialis anterior (TA) and triceps surae (TS) muscles. Thirty-six participants from two cohorts with equal representation of younger (20–30 years) and older (60–85 years) cohorts performed isometric dorsi and plantar-flexion at 30% maximal voluntary contraction and their surface electromyograms (sEMG) of TA and TS were recorded. The maximal power spectral density (PM) was computed for the recordings and an analysis of variance statistical test was performed with age and muscle as factors (α = 0.05). The results show that age-associated change of PM was significantly higher for TA compared with TS muscles. This could be attributed to soleus which has been earlier found to have smaller age-related changes. The study highlights the need to consider the disproportionate age-associated changes in sEMG of the two muscles while examining the muscle strength of the elderly.

Sex differences in age-related changes on peripheral warm and cold innocuous thermal sensitivity

Cutaneous thermal sensitivity to a warm and cold stimulus was compared amongst 12 older (OF, 65.2±1.0year) and 29 younger (YF, 21.6±0.2years) female participants, and 17 older (OM, 66.2±1.5years) and 13 younger (YM, 21.2±0.4years) male participants to examine the effects of ageing and sex. In a neutral condition (27.5°C, 50% RH) during rest, warm and cold thermal sensitivity was measured on eight body regions (forehead, chest, back, forearm, hand, thigh, calf, and foot). Using the method of limits, a thermal stimulator was applied to the skin at an adapting temperature and either increased or decreased at a constant rate (0.3°C/s) until the participants detected the temperature with a push button. Thermal sensitivity declined with ageing to both a cold (older: 1468.6±744.7W/m2, younger: 869.8±654.7W/m2, p<0.001) and warm (older: 2127.0±1208.3W/m2, younger: 1301.7±1055.2W/m2, p<0.001) innocuous stimulus. YF and OF were more sensitive than YM and OM to both a warm and cold stimulus (p<0.05). There was no interaction between age and sex suggesting that whilst thermal sensitivity decreases with age the decrease is similar between the sexes (p>0.05). There was an interaction between temperatures, age and location and it seemed that cold thermal sensitivity was more homogenous for young and older participants however warm thermal sensitivity was more heterogeneous especially in the younger participants (p<0.05). Although the pattern was not similar between ages or sexes it was evident that the forehead was the most sensitive region to a warm and cold stimulus. Interestingly the decline in sensitivity observed with ageing occurred for all locations but was attenuated at the forehead in both males and females (p>0.05).

Sex difference in age-related changes in knee extensor strength and power production during a 10-times-repeated sit-to-stand task in Japanese elderly.

BackgroundFor middle-aged and elderly women, age-related decline in an index representing power production during STS task (STS-PI), calculated by using an equation reported previously, has been shown to be greater than that in the force generation capability of lower extremity. Whether this is specific to women remains unclear. This study examined how the age-related changes in knee extensor strength and power production during STS differ between Japanese men and women aged 65 years or older.MethodsThe time taken for a 10-times-repeated STS test (STS time) and force developed during maximal voluntary isometric knee extension (KE-F) were determined in Japanese younger-old (262 men and 285 women) aged 65–74 years and older-old (96 men and 89 women) aged 75–90 years. STS-PI was calculated using the following equation: STS-PI = (body height − 0.4) × body mass × 10/STS time.ResultsKE-F and STS-PI were significantly greater in the younger-old than in the older-old group (p < 0.0001) and in men than in women (p < 0.0001). STS-PI and KE-F, expressed as the percentages of the mean value of the corresponding variable for the younger-old group (%STS-PI and %KE-F, respectively), were negatively correlated to chronological age in both men (r = −0.386 and r = −0.269, respectively, p < 0.0001) and women (r = −0.504 and r = −0.294, respectively, p < 0.0001). Regression slopes in the relationship between age and %KE-F were not significantly different between men (−1.521) and women (−1.618). However, regression slope in the relationship between age and %STS-PI was significantly steeper in women (−3.108) than in men (−2.170) (p < 0.05). In OOG, %KE-F had no significant effect of sex, but %STS-PI was significantly lower in women than in men (p < 0.001).ConclusionsIn Japanese men and women aged 65 years or over, age-related loss in power production during STS is steeper in women than in men, with greater magnitude than that in knee extensor strength. This suggests a higher priority of improving power generation capability during whole-body movement such as STS in older women than in older men.

Differential age-related changes in N170 responses to upright faces, inverted faces, and eyes in Japanese children.

The main objectives of this study were to investigate the development of face perception in Japanese children, focusing on the changes in face processing strategies (holistic and/or configural vs. feature-based) that occur during childhood. To achieve this, we analyzed the face-related N170 component, evoked by upright face, inverted face, and eyes stimuli in 82 Japanese children aged between 8- and 13-years-old. During the experiment, the children were asked to perform a target detection task in which they were told to press a button when they saw images of faces or kettles with mustaches, glasses, and fake noses; i.e., an implicit face perception task. The N170 signals observed after the presentation of the upright face stimuli were longer in duration and/or had at least two peaks in the 8–11-year-old children, whereas those seen in the 12–13-year-old children were sharp and only had a single peak. N170 latency was significantly longer after the presentation of the eyes stimuli than after the presentation of the upright face stimuli in the 10- and 12-year-old children. In addition, significant differences in N170 latency were observed among all three stimulus types in the 13-year-old children. N170 amplitude was significantly greater after the presentation of the eyes stimuli than after the presentation of the upright face stimuli in the 8–10- and 12-year-old children. The results of the present study indicate that the upright face stimuli were processed using holistic and/or configural processing by the 13-year-old children.

Evidence for age-associated cognitive decline from Internet game scores

IntroductionLumosity's Memory Match (LMM) is an online game requiring visual working memory. Change in LMM scores may be associated with individual differences in age-related changes in working memory. MethodsEffects of age and time on LMM learning and forgetting rates were estimated using data from 1890 game sessions for users aged 40 to 79 years. ResultsThere were significant effects of age on baseline LMM scores (β = −.31, standard error or SE = .02, P < .0001) and lower learning rates (β = −.0066, SE = .0008, P < .0001). A sample size of 202 subjects/arm was estimated for a 1-year study for subjects in the lower quartile of game performance. DiscussionOnline memory games have the potential to identify age-related decline in cognition and to identify subjects at risk for cognitive decline with smaller sample sizes and lower cost than traditional recruitment methods.

Age-related changes in intrinsic function of the superior temporal sulcus in autism spectrum disorders.

Currently, the developmental trajectories of neural circuits implicated in autism spectrum disorders (ASD) are largely unknown. Here, we specifically focused on age-related changes in the functional circuitry of the posterior superior temporal sulcus (pSTS), a key hub underlying social-cognitive processes known to be impaired in ASD. Using a cross-sectional approach, we analysed resting-state functional magnetic resonance imaging (fMRI) data collected from children, adolescents and adults available through the autism brain imaging data exchange repository [n = 106 with ASD and n = 109 typical controls (TC), ages 7-30 years]. The observed age-related changes of pSTS intrinsic functional connectivity (iFC) suggest that no single developmental pattern characterizes ASD. Instead, pSTS circuitry displayed a complex developmental picture, with some functional circuits showing patterns consistent with atypical development in ASD relative to TC (pSTS-iFC with fusiform gyrus and angular gyrus) and others showing delayed maturation (pSTS-iFC with regions of the action perception network). Distinct developmental trajectories in different functional circuits in ASD likely reflect differential age-related changes in the socio-cognitive processes they underlie. Increasing insight on these mechanisms is a critical step in the development of age-specific interventions in ASD.

Age-associated changes in the retinal nerve fiber layer and optic nerve head.

Optical coherence tomography (OCT) measures of the retinal nerve fiber layer (RNFL) thickness and neuroretinal rim (NRR) parameters are often used as a surrogate for retinal ganglion cell content. The purpose of this study was to investigate the relationship between these morphological measures and the aging effects on these structures. One hundred thirteen healthy individuals, aged 19 to 76 years, with no prior history of retinal of optic nerve head pathology were recruited. A circumpapillary and radial OCT scan centered on the optic nerve head (ONH) was used for data analysis. Transverse scaling was calculated for each subject using measures from optical biometry. Custom algorithms were used for morphological analysis of the ONH NRR and RNFL that included quantification of major retinal vascular contribution. There was a significant age-related loss of RNFL thickness (-0.23 μm/y, R(2) = 0.24, P < 0.01), major retinal vascular contribution (-0.03 μm/y, R(2) = 0.07, P = 0.01, neural rim volume (NRV, -0.004 mm(3)/y, R(2) = 0.15, P < 0.01), and minimum rim width (MRW, -1.77 μm/y, R(2) = 0.23, P < 0.01) before, and after, incorporating the Bruch's membrane opening size (sMRW, -1.86 μm/y, R(2) = 0.22, P < 0.01). When normalized, the rates of change for ONH NRR parameters (NRV, 0.69%/y and sMRW, 0.50%/y) exceeded that of RNFL thickness (0.19%/y, P < 0.01). Although both RNFL and ONH NRR parameters contain axons of retinal ganglion cells, there are differences in age-related changes in these measures that should be considered in clinical application.

The aging mouse partially models the aging human spine: lumbar and coccygeal disc height, composition, mechanical properties, and Wnt signaling in young and old mice.

Murine lumbar and coccygeal (tail) regions of spines are commonly used to study cellular signaling of age-related disc diseases, but the tissue-level changes of aging intervertebral discs and vertebrae of each spinal region remain unclear. Furthermore, the impact of aging lumbar and coccygeal discs on Wnt/β-catenin signaling, which is putatively involved in the catabolism of intervertebral discs, is also unclear. We compared disc/vertebrae morphology and mechanics and biochemical composition of intervertebral discs from lumbar and coccygeal regions between young (4-5 mo) and old (20-22 mo) female C57BL/6 mice. Center intervertebral disc height from both regions was greater in old discs than young discs. Compared with young, old lumbar discs had a lower early viscous coefficient (a measure of stiffness) by 40%, while conversely old coccygeal discs were stiffer by 53%. Biochemically, old mice had double the collagen content in lumbar and coccygeal discs of young discs, greater glycosaminoglycan in lumbar discs by 37%, but less glycosaminoglycan in coccygeal discs by 32%. Next, we compared Wnt activity of lumbar and coccygeal discs of 4- to 5-mo and 12- to 14-mo TOPGAL mice. Despite the disc-specific changes, aging decreased Wnt signaling in the nucleus pulposus from both spinal regions by ≥64%. Compared with young, trabecular bone volume/tissue volume and ultimate force were less in old lumbar vertebrae, but greater in old coccygeal vertebrae. Thus intervertebral discs and vertebrae age in a spinal region-dependent manner, but these differential age-related changes may be uncoupled from Wnt signaling. Overall, lumbar and coccygeal regions are not interchangeable in modeling human aging.

Strain-specific differences in age-related changes in rat susceptibility to experimental autoimmune encephalomyelitis and dendritic cell cytokine gene expression

Experimental autoimmune encephalomyelitis (EAE) is an animal model of multiple sclerosis, a prototype of Th1/Th17-mediated organ-specific autoimmune disease. In the rat, susceptibility to development of these diseases is shown to be strain-and age-dependent. In adult rats of distinct strains, it correlates with splenic dendritic cell (DC) subset composition, which also exhibit age-related changes. The aim of this study was to examine influence of aging on: i) Albino Oxford (relatively resistant to EAE) and Dark Agouti (susceptible to EAE) rat development of EAE and ii) their splenic conventional (OX62+) DC population in respect to its subset composition and expression of mRNAs for proinflammatory and immunosuppressive cytokines. We used 3month-old (young) and 26-month-old (aged) rats of AO and DA strain. The rats were immunized for EAE with rat spinal cord homogenate in complete Freund?s adjuvant and clinical course of the disease was followed. Fresh OX62+DCs were examined for the expression of CD4 (using flow cytometry) and genes encoding cytokines influencing DC activation/maturation (TNF-? and IL-6) using RT-PCR. Additionally, in vitro lipopolysaccharide (LPS) activated/matured DCs were examined for the expression of genes encoding cytokines controlling Th1/Th17 cell polarization using RT-PCR. With aging, AO rats became more susceptible, whereas DA rats largely lose their susceptibility to the induction of EAE. In AO rats aging shifted CD4+:CD4DC ratio towards CD4-cells, producing large amount of proinflammatory cytokines, whereas in DA rats CD4+:CD4-DC ratio remained stable with aging. In fresh DCs from rats of both the strains the expression of TNF-? mRNA increased with aging, whereas that of IL-6 mRNA decreased and increased in DCs from AO and DA rats, respectively. Following in vitro LPS stimulation OX62+ DCs from aged AO rats up-regulated the expression of mRNA for IL-23p19 (specific subunit of IL-23; crucial for sustained IL-17 production) and IL-1? (positive IL-17 regulator), whereas down-regulated the expression of IL-10 (negative IL-17 regulator) when compared with young strain-matched rats. In DA rats aging incresed IL-23p19 mRNA expression in LPS-stimulated DCs, whereas exerted the opposing effects on the expression of mRNAs for IL-10 and IL-1? compared to AO rats. Irrespective of the rat strain, aging did not influence mRNA expression for IL-12p35 (driving Th1 polarization) in DCs. Overall, results suggest role of changes in the expression of genes encoding proinflammatory and immunosuppressive cytokines in development of age-related alterations in rat susceptibility to EAE induction.

Trends in Triathlon Performance: Effects of Sex and Age

The influences of sex and age upon endurance performance have previously been documented for both running and swimming. A number of recent studies have investigated how sex and age influence triathlon performance, a sport that combines three disciplines (swimming, cycling and running), with competitions commonly lasting between 2 (short distance: 1.5-km swim, 40-km cycle and 10-km run) and 8 h (Ironman distance: 3.8-km swim,180-km cycle and 42-km run) for elite triathletes. Age and sex influences upon performance have also been investigated for ultra-triathlons, with distances corresponding to several Ironman distances and lasting several days, and for off-road triathlons combining swimming, mountain biking and trail running. Triathlon represents an intriguing alternative model for analysing the effects of age and sex upon endurance and ultra-endurance ([6 h) performance because sex differences and age-related declines in performance can be analysed in the same individuals across the three separate disciplines. The relative participation of both females and masters athletes (age[40 years) in triathlon has increased consistently over the past 25 years. Sex differences in triathlon performance are also known to differ between the modes of locomotion adopted (swimming, cycling or running) for both elite and non-elite triathletes. Generally, time differences between sexes in swimming have been shown to be smaller on average than during cycling and running. Both physiological and morphological factors contribute to explaining these findings. Performance density (i.e. the time difference between the winner and tenth-placed competitor) has progressively improved (time differences have decreased) for international races over the past two decades for both males and females, with performance density now very similar for both sexes. For age-group triathletes, sex differences in total triathlon performance time increases with age. However,the possible difference in age-related changes in the physiological determinants of endurance and ultra-endurance performances between males and females needs further investigation. Non-physiological factors such as low rates of participation of older female triathletes may also contribute to the greater age-related decline in triathlon performance shown by females. Total triathlon performance has been shown to decrease in a curvilinear manner with advancing age. However, when triathlon performanceis broken down into its three disciplines, there is a smaller age-related decline in cycling performance than in running and swimming performances. Age-associated changes in triathlon performance are also related to the total duration of triathlon races. The magnitude of the declines in cycling and running performances with advancing age for short triathlons are less pronounced than for longer Ironman distance races. Triathlon distance is also important when considering how age affects the rate of the decline in performance. Off-road triathlon performances display greater decrements with age than road-based triathlons, suggesting that the type of discipline (road vs. mountain bike cycling and road vs. trail running) is an important factor in age-associated changes in triathlon performance.Finally, masters triathletes have shown relative improvements in their performances across the three triathlon disciplines and total triathlon event times during Ironman races over the past three decades. This raises an important issue as to whether older male and female triathletes have yet reached their performance limits during Ironman triathlons

Age Differences in Executive Functions within a Sample of Brazilian Children and Adolescents

Executive abilities have been suggested to show differential age-related changes. This study aimed to extend this evidence to a Brazilian sample, which was composed of 572 children and adolescents aged 6 to 14 years, assessed in tests of visual and auditory working memory, selective attention, inhibitory control, cognitive flexibility, attentional abilities, verbal fluency and planning. ANOVAs revealed significant age effect on performance in all tests, with a trend toward better performance with the progression of age, even in differential ways. Overall, the performance on simpler tests, such as the basic attention, increased with age progression until around 11 or 12 years, when performance becomes more stable. However, in more complex tasks, including working memory tasks, the performance showed a more continuous improvement. There was gender effect in two measures: visual working memory, in which boys outperformed girls, and verbal fluency, in which the girls outperformed boys. In general, the results of this Brazilian sample were similar to those reported by studies conducted in other countries, what suggests that Brazilian socio-cultural specificities, at least of the participants of this sample, were not sufficient to reveal a distinct pattern of progression.

Expression of Toll-like receptors and downstream genes in lipopolysaccharide-induced porcine alveolar macrophages

The aim of the present study was to determine the age-related kinetic changes of Toll-like receptors (TLRs) and downstream genes expression, and secretion of cytokine in lipopolysaccharide (LPS) stimulated porcine alveolar macrophages (AM). For this purpose, AMs were isolated from 5-day-old newborn piglets and 120-day-old young pigs. mRNA expression and cytokine measurement was determined by quantitative real-time PCR and ELISA, respectively. First, AMs were incubated for 24h in the absence or presence of increasing concentrations of LPS. Results showed the up-regulation of TLRs 2, 4, 5 and 9 mRNA from all concentrations of LPS used, as compared to non-stimulated cells, and TLR4 was the highest expression in both ages (P<0.05). Furthermore, quantitative analysis demonstrated increased expression of mRNAs encoding TLRs 2, 4, 5 and 9, LBP, CD14, MD2, MyD88, IRAK4 and TRAF6 in both ages in a time-dependant manner (P<0.05). Overall, LPS inducible mRNA for TLR4, LBP, CD14 and MyD88 had higher expression in newborn piglets compared with those of young pigs (P<0.05). The level of cytokine protein IL6 and TNFα in supernatant fluid significantly varied with time of incubation and age of animals. Their concentration increased immediately at 1h after LPS stimulation and remained significantly higher up to 48h in both ages. Production of pro-inflammatory cytokine protein IL6 and TNFα in supernatant was significantly higher in young pigs than those of piglets. This study suggests that differential age-related changes in the expression of TLRs and downstream genes, and pro-inflammatory cytokine could contribute to a different age-related innate immune response during pulmonary infection. Further investigation is warranted to determine the precise effects of LPS on porcine AMs by means of a functional study across a wider age range.