Linear Effect Of Age Research Articles

Genetic Parameter Estimates for Carcass and Meat Quality Traits and Their Genetic Associations With Sexual Precocity Indicator Traits in Nellore Cattle.

For developing beef cattle breeding programmes, it is essential to understand the genetic basis of economically relevant traits, such as carcass, meat quality and female sexual precocity. However, the direct selection of most of these traits is a challenge for producers because of the high cost and measurement difficulty. Genetic correlation estimates between carcass and meat quality traits obtained after slaughter and sexual precocity indicator traits in Nellore are limited in the literature. Thus, this study aimed to estimate genetic parameters for longissimus muscle area (LMA), backfat thickness (BF), hot carcass weight (HCW), shear force tenderness (SF), marbling score (MARB), intramuscular fat content (IMF), age at first calving (AFC), heifer pregnancy (HP) and scrotal circumference (SC) in Nellore cattle, using pedigree and genomic information. For this, data from 6910 young bulls with phenotypic information for carcass and meat traits, 230,682 for sexual precocity indicator traits, and 17,850 animals genotyped with or imputed to the Illumina Bovine HD BeadChip were used. The (co)variance components and genetic parameters were estimated considering BLUP and single-step GBLUP (ssGBLUP) models via Bayesian inference using the GIBBSF90+ software. The multi-trait animal model included additive and residual genetic effects as random; the fixed effects of contemporary group (for all traits) and date of analysis as classes (for BF, SF and MARB); and the linear effects of age at slaughter (all carcass and meat traits) and age at yearling (YW and SC) as covariates. Heritability estimates ranged from 0.13 to 0.34 for carcass and meat quality traits, and for SC, AFC and HP, were 0.33, 0.07 and 0.29, respectively. Favourable genetic correlations were estimated between YW-HCW (0.79 ± 0.03), YW-LMA (0.28 ± 0.05), YW-SC (0.35 ± 0.03), HCW-LMA (0.44 ± 0.05), HCW-SF (-0.22 ± 0.09), HCW-SC (0.19 ± 0.05), MARB-IMF (0.90 ± 0.07), SF-IMF (-0.20 ± 0.11), BF-MARB (0.29 ± 0.08), BF-IMF (0.22 ± 0.09), BF-AFC (-0.21 ± 0.07) and BF-HP (0.24 ± 0.10). In general, the correlations between carcass traits and those of meat quality were low to moderate. Additionally, carcass and meat quality traits did not exhibit strong genetic correlations with female precocity indicators. So, to achieve significant genetic advances in female sexual indicator traits, carcass composition and meat quality, these traits must compose selection indices for Nellore cattle.

The course of children's mental health symptoms during and beyond the COVID-19 pandemic.

The COVID-19 pandemic is associated with increases in child mental health problems, but the persistence of these changes in the post-pandemic era remains uncertain. Additionally, it is unclear whether changes in mental health problems during the pandemic exceed the anticipated increases as children age. This study controls for the linear effect of age in 1399 children, investigating the course of child-reported anxiety, depression, hyperactivity, and inattention symptoms during and after the pandemic, and identifies risk and protective factors that predict these mental health trajectories. Children (51% male; ages 9-11 at the first timepoint) provided mental health ratings at three pandemic timepoints (July-August 2020; March-April 2021; November 2021-January 2022) and one post-pandemic timepoint (January-July 2023). Mothers reported pre-pandemic mental health (2017-2019) and socio-demographic factors. Children reported socio-demographic factors, risk (e.g. screen time, sleep), and resilience (e.g. optimism) factors during the first timepoint. Average mental health symptoms increased over time, with more children exceeding clinical cut-offs for poor mental health at each subsequent pandemic timepoint. Growth curve modeling, adjusting for age-related effects, revealed a curvilinear course of mental health symptoms across all domains. Examination of risk and protective factors revealed that pre-existing mental health symptoms and optimism were associated with the course of symptoms. After considering age effects, children's mental health follows a curvilinear pattern over time, suggesting an initial decline followed by a rising trend in symptoms post-COVID. These findings underscore the continued need for additional resources and timely, evidence-based mental health prevention and intervention for children.

Normative Data Study of Verbal Fluency and Naming Tests in Elderly People in Costa Rica

Abstract Objective To generate normative data for the Verbal Fluency Test (VFT) and the Boston Naming Test (BNT) in the Costa Rican population. Method The sample consisted of 563 healthy older people (aged 59–90 years). Polynomial multiple regression analyses were run to evaluate the effects of the age, sex, and education variables on VFT and BNT scores. Results The results showed a significant linear effect of education on the four-letter VF scores and an effect of sex on the letter P score, with females performing better than males. The explained variance ranged from 20.9% to 28.3%. A linear effect of age and education was also found for the four semantic VF scores, with scores decreasing with increasing age and lower education. The sex variable was significant for all semantic categories, with females performing better than males except in the animal category. The explained variance ranged from 21.7% to 30.9%. In the BNT, a linear effect of education was found, so that the more education, the better the score. In addition, a sex effect was also found, with males having higher scores than females. The predictors of the model explained 9.6% of the variance. Conclusions This is the first study that generates normative data for the VF and BNT in the Costa Rican population over 59 years of age based on demographic variables. The use of these normative data will help clinicians in Costa Rica to better understand language functioning in the elderly, allowing for better classification and diagnosis in the future.

Toward early intervention based on age-specific vision checkups: A vision impairment survey in Yantai, China.

The prevalence of myopia among children and adolescents is currently rising to alarming levels (>80%) in China. This study used several routinely collected demographic factors to quantify myopia and glass-wearing rates for primary and secondary school students. We identified myopia risk factors and proposed new aspects for early intervention. This study was a cross-sectional survey of myopia and glass-wearing rates for students (6-18 years old) in Yantai, China. We collected both vision (vision acuity [VA] and spherical equivalence [SE]) and glass-wearing information to establish respective logistic models for quantifying myopia and glass-wearing rate. We further propose a joint decision region (VA, SE, age) to guide early intervention. Among 10,276 children, 63% had myopia (65% wore glasses). The prevalence of myopia increases with age and levels off during adulthood. Females had a higher overall prevalence rate than males (P < .001). The rural age mode (≈15.5) is about 2 years larger than the urban age (≈13.5) for myopia students. For the myopia rate, in the age ≤14.5, the linear age effect was significant (odds ratio [OR] = 1.73, P < .0001), males had a significant negative baseline effect at the start of schooling (vs. females) (OR = 0.68, P < .0001), and the urban group had a significant positive baseline effect (vs. rural) (OR = 1.39, P < .0001). The correlation between VA and SE increases with age and has a directional shift (from negative to positive) at ages 8 to 9. For the glass-wearing rate, age had a significant positive effect (OR = 1.25, P < .0001), VA had a significant negative effect (OR = 0.002, P < .0001), and body mass index had a slightly significant positive effect (OR = 1.02, P = .03). Urban female have a higher myopia rate than rural male at the start of schooling, and vocational high school has improved vision upon high school. Body mass index was not a significant factor for myopia. The myopia rate model is specific to age range (separated at 14.5 years old). Students of lower ages are less likely to wear glasses for correction, and this may require intervention. The temporal age-specific (VA, SE) correlations and joint distributions strengthen the speculation in the literature that age 8 to 9 is a critical intervention period and motivates us to propose a rigorous intervention decision region for (age, VA, and SE) which mainly applies for this tight age period.

Arterial stiffness mediates the association between age and processing speed at low levels of microvascular function in humans across the adult lifespan.

The function of micro- and macrovessels within the peripheral vasculature has been identified as a target for the investigation of potential cardiovascular-based promoters of cognitive decline. However, little remains known regarding the interaction of the micro- and macrovasculature as it relates to cognitive function, especially in cognitively healthy individuals. Therefore, our purpose was to unravel peripheral factors that contribute to the association between age and processing speed. Ninety-nine individuals (51 men, 48 women) across the adult life span (19-81 yr) were used for analysis. Arterial stiffness was quantified as carotid-femoral pulse-wave velocity (cfPWV) and near-infrared spectroscopy assessed maximal tissue oxygenation (Sto2max) following a period of ischemia. Processing speed was evaluated with Trail Making Test (TMT) Parts A and B. Measures of central (cPP) and peripheral pulse pressure (pPP) were also collected. Moderated mediation analyses were conducted to determine contributions to the age and processing speed relation, and first-order partial correlations were used to assess associations while controlling for the linear effects of age. A P ≤ 0.05 was considered statistically significant. At low levels of Sto2max, there was a significant positive (b = 1.92; P = 0.005) effect of cfPWV on time to completion on TMT part A. In addition, cPP (P = 0.028) and pPP (P = 0.027) remained significantly related to part A when controlling for age. These results suggested that the peripheral microvasculature may be a valuable target for delaying cognitive decline, especially in currently cognitively healthy individuals. Furthermore, we reinforced current evidence that pulse pressure is a key endpoint for trials aimed at preventing or delaying the onset of cognitive decline.NEW & NOTEWORTHY Arterial stiffness partially mediates the association between age and processing speed in the presence of low microvascular function, as demarcated by maximum tissue oxygenation following ischemia. Central and peripheral pulse pressure remained associated with processing speed even after controlling for age. Our findings were derived from a sample that was determined to be cognitively healthy, which highlights the potential for these outcomes to be considered during trials aimed at the prevention of cognitive decline.

A - 09 Normative Data of Neuropsychological Tests of Attention in Older Adults from Costa Rica.

To generate normative data for the Trail Making Test (TMT) and the Target Cancellation Task for healthy older adults in Costa Rica. 563 healthy Costa Rican adults aged 59-90years (M = 67.15; SD = 7) were assessed. Each participant was administered the two attention tests as part of a more comprehensive neuropsychological battery. Multiple regression models showed a linear effect of education for TMT-A and TMT-B, as well as a linear and curvilinear effect of age for TMT-B and TMT-A, respectively. The model predictors explained between 27.4% and 30.3% of the variance. For the Target Cancellation Task scores, linear effects of education were observed for all 4 scores, as well as a linear effect of age for the TMX time and Rhombus time scores. The correct TMX score showed a curvilinear effect of age. The predictors of the model explained between 2% and 33.3% of the variance. This is the first normative data generated for the TMT and the Target Cancellation Task in older adults from Costa Rica. This normative data will be used in individuals with a variety of neurological conditions that course with attention deficits to establish the neuropsychological profile of those individuals in this area.

A - 10 Normative Data of Neuropsychological Tests of Language in Older Adults from Costa Rica.

To generate normative data of the Verbal Fluency Test (VFT) and Boston Naming Test (BNT) for healthy older adults in Costa Rica. The sample consisted of 563 healthy Costa Rican adults aged 59-90years (M = 67.15; SD = 7). Each participant was administered the VFT and BNT as part of a more comprehensive neuropsychological battery. Multiple regression models showed a linear effect of education for all 4 phonological verbal fluency (PVF) scores, and a sex effect on VF P, with females performing better than males. The model predictors explained between 20.9% and 28.3% of the variance. In semantic verbal fluency (SVF) scores, linear effects of age and education were observed in all 4 subtests, such that word production decreased with increasing age and lower education. In addition, females scored better in all semantic categories except animals, where there was no effect of sex. The predictors of the model explained between 21.7% and 30.9% of the variance. In BNT, there was a linear effect of education and an effect of sex, so that males scored higher compared to females. The predictors of the model explained 9.6% of the variance. This is the first study to generate normative data for VFT and BNT in older adults from Costa Rica. This data will allow neuropsychologists in the region to perform assessment and diagnostic processes with greater accuracy.

15-item version of the Boston Naming Test: Normative data for the Latin American Spanish-speaking adult population.

Naming is commonly impaired in people with neurodegenerative diseases and brain injury, and as a result, its accurate assessment is essential. The aim of this study was to provide normative data for the 15-item Spanish version of the Boston Naming Test (BNT) for an adult population from eight Latin American countries/regions. The total sample consisted of 2,828 participants from Argentina, Chile, Cuba, El Salvador, Mexico, Honduras, Paraguay, and Puerto Rico. Multiple regressions were used to generate normative data following a four-step process. Regression models showed a linear effect of age on the 15-item BNT total score for Argentina, Chile, Mexico, and Puerto Rico. In contrast, Paraguay showed a quadratic age effect. Almost all countries showed a positive linear effect of education, except Cuba which had a quadratic effect. Sex was a significant predictor in Argentina, Chile, Cuba, and Mexico, where in women scored lower than men. This study generates normative data for the 15-item Spanish version of the BNT and offers a free open-source calculator that will assist in the efficacious use of this neuropsychological test in clinical practice and research. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Age and gender differences in narcissism: A comprehensive study across eight measures and over 250,000 participants.

Age and gender differences in narcissism have been studied often. However, considering the rich history of narcissism research accompanied by its diverging conceptualizations, little is known about age and gender differences across various narcissism measures. The present study investigated age and gender differences and their interactions across eight widely used narcissism instruments (i.e., Narcissistic Personality Inventory, Hypersensitive Narcissism Scale, Dirty Dozen, Psychological Entitlement Scale, Narcissistic Personality Disorder Symptoms from the Diagnostic and Statistical Manual of Mental Disorders, Version IV, Narcissistic Admiration and Rivalry Questionnaire-Short Form, Single-Item Narcissism Scale, and brief version of the Pathological Narcissism Inventory). The findings of Study 1 (N = 5,736) revealed heterogeneity in how strongly the measures are correlated. Some instruments loaded clearly on one of the three factors proposed by previous research (i.e., Neuroticism, Extraversion, Antagonism), while others cross-loaded across factors and in distinct ways. Cross-sectional analyses using each measure and meta-analytic results across all measures (Study 2) with a total sample of 270,029 participants suggest consistent linear age effects (random effects meta-analytic effect of r = -.104), with narcissism being highest in young adulthood. Consistent gender differences also emerged (random effects meta-analytic effect was -.079), such that men scored higher in narcissism than women. Quadratic age effects and Age × Gender effects were generally very small and inconsistent. We conclude that despite the various conceptualizations of narcissism, age and gender differences are generalizable across the eight measures used in the present study. However, their size varied based on the instrument used. We discuss the sources of this heterogeneity and the potential mechanisms for age and gender differences. (PsycInfo Database Record (c) 2023 APA, all rights reserved).

Changes in brain metabolite levels across childhood

Metabolites play important roles in brain development and their levels change rapidly in the prenatal period and during infancy. Metabolite levels are thought to stabilize during childhood, but the development of neurochemistry across early-middle childhood remains understudied. We examined the developmental changes of key metabolites (total N-acetylaspartate, tNAA; total choline, tCho; total creatine, tCr; glutamate+glutamine, Glx; and myo-inositol, mI) using short echo-time magnetic resonance spectroscopy (MRS) in the anterior cingulate cortex (ACC) and the left temporo-parietal cortex (LTP) using a mixed cross-sectional/longitudinal design in children aged 2–11 years (ACC: N = 101 children, 112 observations; LTP: N = 95 children, 318 observations). We found that tNAA increased with age in both regions, while tCho decreased with age in both regions. tCr increased with age in the LTP only. Glx did not show linear age effects in either region, but a follow-up analysis in participants with ≥3 datapoints in the LTP revealed a quadratic effect of age following an inverted U-shape. These substantial changes in neurochemistry throughout childhood likely underlie various processes of structural and functional brain development.

High spatial overlap but diverging age-related trajectories of cortical magnetic resonance imaging markers aiming to represent intracortical myelin and microstructure.

Statistical effects of cortical metrics derived from standard T1- and T2-weighted magnetic resonance imaging (MRI) images, such as gray-white matter contrast (GWC), boundary sharpness coefficient (BSC), T1-weighted/T2-weighted ratio (T1w/T2w), and cortical thickness (CT), are often interpreted as representing or being influenced by intracortical myelin content with little empirical evidence to justify these interpretations. We first examined spatial correspondence with more biologically specific microstructural measures, and second compared between-marker age-related trends with the underlying hypothesis that different measures primarily driven by similar changes in myelo- and microstructural underpinnings should be highly related. Cortical MRI markers were derived from MRI images of 127 healthy subjects, aged 18-81, using cortical surfaces that were generated with the CIVET 2.1.0 pipeline. Their gross spatial distributions were compared with gene expression-derived cell-type densities, histology-derived cytoarchitecture, and quantitative R1 maps acquired on a subset of participants. We then compared between-marker age-related trends in their shape, direction, and spatial distribution of the linear age effect. The gross anatomical distributions of cortical MRI markers were, in general, more related to myelin and glial cells than neuronal indicators. Comparing MRI markers, our results revealed generally high overlap in spatial distribution (i.e., group means), but mostly divergent age trajectories in the shape, direction, and spatial distribution of the linear age effect. We conclude that the microstructural properties at the source of spatial distributions of MRI cortical markers can be different from microstructural changes that affect these markers in aging.

Psychological Obsolescence and Subjective Remaining Life Expectancy are Predictors of Generativity in a Six-Year Longitudinal Study

In this research, we explore associations between (changes in) perceived generativity, subjective remaining life expectancy (SRLE), and psychological obsolescence in a longitudinal sample. We hypothesized a higher SRLE and a weaker obsolescence would be concomitants of higher perceived generativity. We also hypothesized that generativity would exhibit intraindividual fluctuation over time, which should relate to intraindividual fluctuation in the respective concomitants. Using multilevel modeling, several concomitants of generativity were investigated. The sample consisted of 518 German participants (aged 18–88 years) who took part in at least two of four measurement waves of the Ageing-as-Future online study spanning over 6 years. There was no mean-level increase or decrease in generativity over the 6-year study period. Despite this absence of linear time trends, individual perceived generativity still fluctuated considerably over time. The model showed that higher individual average SRLE and lower individual average psychological obsolescence resulted in higher average perceived generativity. Individual fluctuations in those constructs coincided likewise, implying that when individual SRLE increased and individual obsolescence decreased between two time points, perceived generativity tended to increase as well. There were significant quadratic, but no linear age effects. The findings suggest that perceived generativity depends not only on chronological age but several other time-related factors. Based on such results, we discuss implications for interventions and future research.

Age Differences in Heritability of a Latent Dementia Index Score in Men and Women

AbstractBackgroundHeritability estimates of dementia are ∼50‐60% of the total variance across older adulthood. Earlier age of onset, however, might be associated with greater genetic influence whereas older age of onset might be associated with greater environmental influences. The categorical nature of dementia diagnosis outcomes has made testing the relative importance of genetic and environmental influences on dementia difficult due to low statistical power. To overcome this methodological limitation, we tested linear and quadratic effects of age on genetic and environmental variance underlying a continuous measure of dementia likelihood in men and women.MethodThe analytic sample was 5,670 (53% female) pairs of twins from 10 studies in the Interplay of Genes and Environment Across Multiple Studies (IGEMS) consortium. Dementia likelihood is quantified continuously using a latent dementia index measure that is estimated from twins’ available cognitive, memory‐specific, and functional ability measures. Linear and quadratic age differences in genetic and environmental influences on dementia likelihood were tested by modeling univariate correlation between twins’ dementia scores as a linear function of zygosity and age in Mplus. Separate models were estimated for male and female twin groups.ResultsAge moderated genetic and environmental influences on dementia likelihood scores. Both genetic and nonshared environmental variance increased as a function of age, whereas common environmental variance declined. Sex significantly moderated the effect of zygosity on the twin correlations (monozygotic male: .57, monozygotic female: .51, dizygotic male: .19, dizygotic female: .25). Notably, MZ twin correlations were consistent with previously reported heritability estimates for dementia. The pattern of age moderation was the same in men as women, although the linear effect of age on both genetic and common environmental influences was greater in men than women (see Figure 1).ConclusionAge linearly moderated genetic and environmental variance underlying dementia likelihood similarly for both men and women, despite quantitative genetic and environmental sex differences in dementia likelihood. Genetic variance accounted for similar proportions of total variance at younger ages, whereas genetic variance accounted for greater variance in men than in women at older ages.

Age, Period, and Cohort Effects on Literacy Skills across Life Stages

Literacy skills are essential adult competencies for economic, social, political and cultural participation, which are linked to higher quality of life. Literacy skills are known to be lower for older age groups. However, relatively little is known about cohort and period effects, which provide clues to the sociohistorical impacts on literacy, in addition to the well-known age effects, over the life course. This study analyzed three nationally representative cross-sectional survey data of the U.S. adults at five time points, from the 1994 International Adult Literacy Survey (IALS), 2003 Adult Literacy and Life Skills Survey (ALL), and the 2012/2014/2017 Program for International Assessment of Adult Competencies (PIAAC). The total analytic sample was 17,450 adults age between 18 and 65 years old. The literacy measures were re-scaled (0-500 points) to be comparable across the surveys. An age-period-cohort hierarchical linear model (i.e., cross-classified random effects model) was constructed using the Bayes estimator. Individuals were cross-classified based on 14 five-year birth cohort and 5 periods (survey years) information. Results showed that literacy skills improved [95% credibility-interval (CI) for linear effect of age = (0.31, 1.07), but the rate of improvement declined over time, faster rates of decline in later life stages [95% CI for quadratic effect of age = (-0.17, -0.09)]. Additionally, the notable variability across the cohorts and periods [95% CI variances = (5.34, 52.52) and (2.30, 172.01), respectively] were identified. Possible explanations for the identified age, period and cohort effects on literacy and implications for adult competencies in later life are evaluated.

Distant histories of mild traumatic brain injury exacerbate age-related differences in white matter properties

We examined associations of distant histories of mild traumatic brain injury (mTBI) with non-linear and linear trajectories of white matter (WM) properties across a wide age range (23–77). Diffusion tensor imaging (DTI) data obtained from 171 Veterans with histories of clinically diagnosed mTBIs and 115 controls were subjected to tractography, isolating 20 major WM tracts. Non-linear and linear effects of age on each tract's diffusion properties were examined in terms of their interactions with group (mTBI and control). The non-linear model revealed 7 tracts in which the mTBI group's DTI metrics rapidly deviated from control trajectories in middle and late adulthoods, despite the injuries having occurred in the late 20s, on average. In contrast, no interactions between prior injuries and age were detected when examining linear trajectories. Distant mTBIs may thus accelerate normal age-related trajectories of WM degeneration much later in life. As such, life-long histories of head trauma should be assessed in all patients in their mid-to-late adulthoods, whether neurologically healthy or presenting with seemingly unrelated neuropathology.

Effect of age and different doses of dietary vitamin E on breast meat qualitative characteristics of finishing broilers.

The supplementation of vitamin E on broiler chicken diets is essential to the prevention of lipid oxidation reactions in the meat and improvement of meat quality. The objective of this study was to assess the effect of different doses of dietary vitamin E on breast meat quality of broiler chickens in the finishing period. Five doses of vitamin E were used (30, 90, 150, 210, and 270 mg/kg feed) in broilers' diets from 42 to 54 d of age. A completely randomized design was conducted, followed by a split-plot, where the vitamin E dose was considered as the whole plot, and broilers’ age at slaughter was the subplot. Breast meat quality was assessed at 4 different ages (45, 48, 51, and 54 d old), using 50 birds per age, totaling 200 birds. Meat quality characteristics evaluated were: pH at 24 h post mortem, color (brightness, redness, and yellowness), water holding capacity, cooking loss, shear force, and lipid peroxidation. There was no interaction between age and dose of vitamin E for meat quality characteristics (P > 0.05). The age at slaughter had a quadratic effect (P < 0.05) on pH, brightness, redness, and water holding capacity. Although pH values were higher in the breast meat of older birds (51 and 52 d old), breast meat of younger birds (48 d) had a more reddish aspect. Shear force value was higher in breast meat of birds slaughtered at later ages (P < 0.01), as a linear age-effect was observed. Brightness increased linearly (P < 0.05) with higher vitamin doses, whereas treatments did not alter yellowness, cooking loss, and lipid peroxidation. In this study, increasing vitamin E doses in the finishing period increased the brightness of broiler breast meat, whereas slaughtering at later ages resulted in greater meat pH and shear force value.

Functional plasticity abnormalities over the lifespan of first-episode patients with major depressive disorder: a resting state fMRI study.

BackgroundNeurodevelopmental and neurodegenerative theories of depression suggest that patients with major depressive disorder (MDD) may follow abnormal developmental, maturational, and aging processes. However, a lack of lifespan studies has precluded verification of these theories. Herein, we analyzed functional magnetic resonance imaging (fMRI) data to comprehensively characterize age-related functional trajectories, as measured by the fractional amplitude of low frequency fluctuations (fALFF), over the course of MDD.MethodsIn total, 235 MDD patients with age-differentiated onsets and 235 age- and sex-matched healthy controls (HC) were included in this study. We determined the pattern of age-related fALFF changes by cross-sectionally establishing the general linear model (GLM) between fALFF and age over a lifespan. Furthermore, the subjects were divided into four age groups to assess age-related neural changes in detail. Inter-group fALFF comparison (MDD vs. HC) was conducted in each age group and Granger causal analysis (GCA) was applied to investigate effective connectivity between regions.ResultsCompared with the HC, no significant quadratic or linear age effects were found in MDD over the entire lifespan, suggesting that depression affects the normal developmental, maturational, and degenerative process. Inter-group differences in fALFF values varied significantly at different ages of onset. This implies that MDD may impact brain functions in a highly dynamic way, with different patterns of alterations at different stages of life. Moreover, the GCA analysis results indicated that MDD followed a distinct pattern of effective connectivity relative to HC, and this may be the neural basis of MDD with age-differentiated onsets.ConclusionsOur findings provide evidence that normal developmental, maturational, and ageing processes were affected by MDD. Most strikingly, functional plasticity changes in MDD with different ages of onset involved dynamic interactions between neuropathological processes in a tract-specific manner.

The influence of age and environmental conditions on supplement intake by beef cattle winter grazing northern mixed-grass rangelands.

This study evaluated the influence of cow age and temperature adjusted for wind chill (Twindchill) on supplement intake behavior of beef cattle winter grazing northern mixed grass prairie rangelands. A commercial herd of 272 (year 1) and 302 (year 2) bred cows (Angus, Simmental × Angus) ranging in age from 1- to 12-yr-old grazed a 329-ha rangeland pasture (~1.5 ha animal unit month- 1) from November to January. Cows were grouped into seven age classes (1 yr old, 2 yr old, 3 yr old, 4 yr old, 5 yr old, 6 yr old, and ≥ 7 yr old) and were provided free-choice access to a 30% CP self-fed canola meal-based pelleted supplement with 25% salt to limit intake. The target daily intake was 0.91 kg cow- 1 d- 1. Supplement was provided in a SmartFeed Pro self-feeder system to measure individual animal supplement intake and behavior. An Onset HOBO U30-NRC Weather Station was placed near the supplement feeders to collect weather data for the entirety of the grazing period. Average daily supplement intake and the coefficient variation in supplement intake displayed a Twindchill × cow age × year interaction (P ≤ 0.02). There was a negative linear effect of age on supplement intake (kg cow- 1 d- 1) for days with below average Twindchill conditions in both years (P < 0.01). There was also negative linear effect of age on supplement intake (g kg of BW- 1 d- 1) at average Twindchill in year 1 and below average Twindchill in year 2 (P < 0.01). Cow age had a quadratic effect on supplement intake for days with below average Twindchill in year 1 (P = 0.02); however, this was a curvilinear response where yearlings and 2-yr-olds consumed more supplement per kilogram of BW than other age cattle (P < 0.01). Cow age had positive linear effects on variation in supplement intake at below average Twindchill conditions in both years (P < 0.01). Daily visits to the supplement feeders displayed a Twindchill × cow age interaction (P < 0.01), where there was a linear decrease in visits with increasing age at below average Twindchill conditions (P < 0.01). In summary, both cow age and the winter environmental conditions interacted to influence animal supplement intake behavior and, as a result, nutrient delivery efficacy in winter grazing beef cattle.

Change of depressive symptoms in a French nine-year longitudinal study of aging: Gender differences and relationships between social support, health status and depressive symptoms

ObjectivesThe aims of this study were to examine the trajectory of depressive symptoms among older French people, to investigate the role of gender in the developmental trajectory of depressive symptoms and to explore whether the linear increase in depressive symptoms might be accentuated or attenuated at time points during which the older adults’ scores on social support and health satisfaction scales were higher than their individual averages. Methods/materialsData were used from a subsample of older adults living at home who participated in a longitudinal study initiated by researchers from the University of Tours. They were collected at five time points over a 9-year period (T1: 2003; T2: 2005; T3: 2007; T4: 2009; T5: 2011). This study included 707 participants, and multilevel growth curve analysis was used on measures of depressive symptoms, gender differences, social support and health satisfaction. ResultsResults indicated (1) a significant positive linear effect of age on depressive symptoms; (2) that women reported significantly higher scores of depressive symptoms than men at 63 years old (i.e., intercept) and that this gender difference remained constant across age; (3) that the slope of depressive symptoms appeared to increase at time points during which participants had higher levels of social support and to decrease when they had greater health satisfaction. ConclusionThis study provides pertinent information about the change of depressive symptoms in older people living at home and particularly highlights the interest in studying gender, social support and health satisfaction.

LIFESPAN AGE-RELATED DIFFERENCES IN THE REGIONAL WHITE MATTER MICROSTRUCTURE OF THE HUMAN CORPUS CALLOSUM

The corpus callosum (CC) connects homologous cortical structures across hemispheres and is the largest white matter tract in the human brain. Post-mortem studies suggest that CC myelination begins in infancy, reaches a plateau in the middle age, and declines in the later years. The latter is accompanied by myelin disruption and reduction in fiber density and diameter, i.e. changes in intra-/extracellular water space. We used multi-echo T2 imaging to estimate, via multi-exponential T2 relaxation of water, the myelin water fraction (MWF), a direct proxy for myelin content, and geometric mean T2 (geomT2IEW) that reflects water in the intra-/extracellular space, to investigate age differences in five CC regions covering its anterior to posterior span in 395 healthy individuals (7-85 years; 161M+235F). The general linear model analysis of MWF showed main effects of age and age-squared conditioned on interactions by CC region. Univariate polynomial regressions on three age groups (7-29, 30-59, and 60-85 years) revealed the overall quadratic association between age and MWF as mainly driven by the positive linear relationship in the youngest group and minimal differences in the remainder of the lifespan, save for two weak negative linear associations in the anterior/middle CC body. With geomT2, a main linear effect of age, and significant interactions between age and age-squared by region were observed. The positive linear association was especially prominent in the regions with greater fiber density. The results are consistent with CC myelination into adulthood and decreased axonal density and diameter but not prominent myelin degeneration in elderly individuals.