Early-life events. Effects on aging

Association between maternal hypothyroidism, baby birth weight, and adult cardiovascular disease risk: insights from ECG measurements

OBJECTIVES

Thyroid hormone (TH) deficiency during pregnancy may affect cardiovascular function in offspring rats. This study aimed to evaluate the effect of TH deficiency during gestation, on the electrocardiogram indices of young and middle-aged offspring of male rats.

METHODS

Eight female rats were equally divided into hypothyroid and control groups. The hypothyroid mothers received 0.025% 6-propyl-2-thiouracil (PTU) in drinking water throughout pregnancy, while control mothers consumed only tap water. Following birth, male rats from each group were observed for 4 months (young age) and 12 months (middle-aged). The group known as fetal hypothyroid (FH) consisted of rats born from hypothyroid mothers. The serum T4 and TSH concentrations from mothers and newborn male rats were assayed at the end of gestation. Lead II electrocardiogram (ECG) was recorded for 5 minutes using Power Lab, AD Instruments.

RESULTS

There was a significant rise in the P wave voltage in young FH rats, whereas, it was decreased in middle-aged control and FH rats. The voltage of QRS decreased and its duration increased in the young and middle-aged FH rats compared to the corresponding control groups. Duration and voltage of the T wave were significantly altered in the young and middle-aged FH groups. PR and QT intervals significantly increased in the young and middle-aged FH groups compared to their controls.

CONCLUSIONS

Maternal hypothyroidism affected the electrocardiogram indices of offspring rats, possibly signaling cardiovascular problems later in life.

It is time to explore the impact of length of gestation and fetal health on the human lifespan

A recently proposed principal law of lifespan (PLOSP) proposes to extend the whole human lifespan by elongating different life stages. As the preborn stage of a human being, gestation is the foundation for the healthy development of the human body. The antagonistic pleiotropy (AP) theory of aging states that there is a trade-off between early life fitness and late-life mortality. The question is whether slower development during the gestation period would be associated with a longer lifespan. Among all living creatures, the length of the gestation period is highly positively correlated to the length of the lifespan, although such a correlation is thought to be influenced by the body sizes of different species. While examining the relationship between lifespan length and body size within the same species, dogs exhibit a negative correlation between lifespans and body sizes, while there is no such correlation among domestic cats. For humans, most adverse gestational environments shorten the period of gestation, and their impacts are long-term. While many issues remain unsolved, various developmental features have been linked to the conditions during the gestation period. Given that the length of human pregnancies can vary randomly by as long as 5 weeks, it is worth investigating whether a slow steady healthy gestation over a longer period will be related to a longer and healthier lifespan. This article discusses the potential benefits, negative impacts, and challenges of the relative elongation of the gestation period.

An enriched environment ameliorates maternal sleep deprivation-induced cognitive impairment in aged mice by improving mitochondrial function via the Sirt1/PGC-1α pathway

BACKGROUND

Early life stress can cause cognitive impairment in aged offspring. Environmental enrichment (EE) is considered to be an effective non-pharmacological treatment for improving cognitive decline. The aim of this research was to evaluate the effect of EE, on cognitive impairment in aged offspring induced by maternal sleep deprivation (MSD) and the underlying mechanisms involved to investigate its potential value in clinical practice.

METHODS

CD-1 damns were subjected or not to sleep deprivation during late gestation. Twenty-one days after birth, the offspring were assigned to standard or EE cages. At 18 months-old, the learning and memory function of the offspring mice was evaluated using Morris water maze. The hippocampal and prefrontal cortical levels of protein, gene, proinflammation cytokines, and oxidative stress indicators was examined by Western blot, real-time polymerase chain reaction, enzyme linked immunosorbent assay, and biochemical assays.

RESULTS

Offspring in MSD group exhibited declined learning and memory abilities compared with control animals. Moreover, the hippocampal and prefrontal cortical levels of Sirtuin1 (Sirt1), peroxisome proliferator-activated receptor-gamma coactivator-1 alpha (PGC-1α), postsynaptic density protein-95, and synaptophysin were lower and those of proinflammation cytokines higher in the MSD group; meanwhile, the superoxide dismutase content was higher and the malondialdehyde and reactive oxygen species contents were lower. However, these deleterious changes were ameliorated by exposure to EE.

CONCLUSIONS

EE attenuates MSD-induced cognitive impairment, oxidative stress, and neuroinflammation and reverses the reduction in synaptic protein levels in aged offspring mice via the Sirt1/PGC-1α pathway.

H3K9ac of TGFβRI in human umbilical cord: a potential biomarker for evaluating cartilage differentiation and susceptibility to osteoarthritis via a two-step strategy

Background

Epidemiological investigation and our previous reports indicated that osteoarthritis had a fetal origin and was closely associated with intrauterine growth retardation (IUGR). Human Wharton’s jelly-derived mesenchymal stem cells (WJ-MSCs) could be programmable to “remember” early-life stimuli. Here, we aimed to explore an early-warning biomarker of fetal-originated adult osteoarthritis in the WJ-MSCs.

Methods

Firstly, two kinds of WJ-MSCs were applied to evaluate their chondrogenic potential in vitro through inducing chondrogenic differentiation as the first step of our strategy, one from newborns with IUGR and the other from normal newborns but treated with excessive cortisol during differentiation to simulate the excessive maternal glucocorticoid in the IUGR newborns. As for the second step of the strategy, the differentiated WJ-MSCs were treated with interleukin 1β (IL-1β) to mimic the susceptibility to osteoarthritis. Then, the expression and histone acetylation levels of transforming growth factor β (TGFβ) signaling pathway and the expression of histone deacetylases (HDACs) were quantified, with or without cortisol receptor inhibitor RU486, or HDAC4 inhibitor LMK235. Secondly, the histone acetylation and expression levels of TGFβRI were further detected in rat cartilage and human umbilical cord from IUGR individuals.

Results

Glycosaminoglycan content and the expression levels of chondrogenic genes were decreased in the WJ-MSCs from IUGR, and the expression levels of chondrogenic genes were further reduced after IL-1β treatment, while the expression levels of catabolic factors were increased. Then, serum cortisol level from IUGR individuals was found increased, and similar changes were observed in normal WJ-MSCs treated with excessive cortisol. Moreover, the decreased histone 3 lysine 9 acetylation (H3K9ac) level of TGFβRI and its expression were observed in IUGR-derived WJ-MSCs and normal WJ-MSCs treated with excessive cortisol, which could be abolished by RU486 and LMK235. At last, the decreased H3K9ac level of TGFβRI and its expression were further confirmed in the cartilage of IUGR rat offspring and human umbilical cords from IUGR newborn.

Conclusions

WJ-MSCs from IUGR individuals displayed a poor capacity of chondrogenic differentiation and an increased susceptibility to osteoarthritis-like phenotype, which was attributed to the decreased H3K9ac level of TGFβRI and its expression induced by high cortisol through GR/HDAC4. The H3K9ac of TGFβRI in human umbilical cord could be a potential early-warning biomarker for predicting neonatal cartilage dysplasia and osteoarthritis susceptibility.

Supplementary Information

The online version contains supplementary material available at 10.1186/s13287-021-02234-8.

Developmental programming of aging trajectory

There is accumulating evidence that aging phenotype and longevity may be developmentally programmed. Main mechanisms linking developmental conditions to later-life health outcomes include persistent changes in epigenetic regulation, (re)programming of major endocrine axes such as growth hormone/insulin-like growth factor axis and hypothalamic-pituitary-adrenal axis and also early-life immune maturation. Recently, evidence has also been generated on the role of telomere biology in developmental programming of aging trajectory. In addition, persisting changes of intestinal microbiota appears to be crucially involved in these processes. In this review, experimental and epidemiological evidence on the role of early-life conditions in programming of aging phenotypes are presented and mechanisms potentially underlying these associations are discussed.

Decreased H3K9ac level of AT2R mediates the developmental origin of glomerulosclerosis induced by prenatal dexamethasone exposure in male offspring rats

This study aimed to demonstrate that prenatal dexamethasone exposure (PDE) can induce kidney dysplasia in utero and adult glomerulosclerosis in male offspring, and to explore the underlying intrauterine programming mechanisms. Pregnant rats were subcutaneously administered dexamethasone 0.2 mg/kg.d from gestational day (GD) 9 to GD20. The male fetus on GD20 and the adult offspring at age of postnatal week 28 were analyzed. The adult offspring kidneys in the PDE group displayed glomerulosclerosis, elevated levels of serum creatinine and urine protein, ultrastructural damage of podocytes, the reduced expression levels of podocyte marker genes, nephrin and podocin. The histone 3 lysine 9 acetylation (H3K9ac) level in the promoter of renal angiotensin II receptor type 2 (AT2R) and its expression were reduced, whereas the angiotensin II receptor type 1a (AT1aR)/AT2R expression ratio was increased. The fetal kidneys in the PDE group displayed an enlarged Bowman's space and a shrunken glomerular tuft, a reduced cortex width and an increase in the nephrogenic zone/cortical zone ratio, reduced the expression level of glial-cell-line derived neurotrophic factor/c-Ret tyrosine kinase receptor (GDNF/c-Ret) signal pathway and podocyte marker genes. Moreover, the H3K9ac and H3K27ac levels of AT2R as well as the gene and protein expression levels of AT2R in fetal kidneys were inhibited by PDE. In vitro, primary metanephric mesenchyme stem cells (MMSCs) were treated with dexamethasone. Overexpression of AT2R reversed the inhibited expression of GDNF/c-Ret and podocin/nephrin induced by dexamethasone, and glucocorticoids receptor antagonist abolished the decreased H3K9ac level and gene expression of AT2R. In conclusion, PDE induced the offspring's kidney dysplasia as well as adult glomerulosclerosis, which was mediated by a sustained decrease in renal AT2R expression via decreasing the H3 K9ac level.

Role of TGFβ Signaling in Maternal Ethanol-Induced Fetal Articular Cartilage Dysplasia and Adult Onset of Osteoarthritis in Male Rats

Based on our previous findings that prenatal ethanol exposure in offspring increased susceptibility to adult osteoarthritis, this study aimed to further investigate the direct toxicity of ethanol on fetal articular cartilage development. Rat bone marrow-derived stroma cells were capsulated in alginate beads, incubated in a chondrogenic differentiation medium, and cultured for 4 weeks with ethanol treatment at concentrations of 0, 4, 20, and 100 mM. Pregnant rats were treated with ethanol (4 g/kg/day) from gestational days (GDs) 9 to 20. At GD20 and postnatal weeks 2, 6, and 12, 8 male offspring were sacrificed, and 8 male offspring rats of 8-weeks old in each group were treated with or without intraarticular injection of papain for 4 weeks to verify the susceptibility of adult osteoarthritis. Ethanol treatment resulted in poor differentiation of bone marrow-derived stroma cells to chondrocytes and suppressed the expression of the transforming growth factor-β (TGFβ)-smad2/3-Sox9 signaling pathway. In animal experiments, the shape of articular cartilage in the ethanol treatment group was more disordered than that of the control group, the matrix was not deep, and the cartilage was thin, which showed poor cartilage development. The TGFβ signaling pathway in the ethanol treatment group was persistently low at all time points. After intraarticular injection of papain, histological analyses, and the Mankin score revealed increased cartilage destruction in the ethanol treatment group. Ethanol caused articular cartilage dysplasia that was programmed in adulthood via a low-functional TGFβ signaling pathway, and the tolerance of this articular cartilage to external stimuli was significantly decreased.

Maternal Preeclampsia and Androgens in the Offspring around Puberty: A Follow-Up Study

Background

Children born after preeclampsia may have a dominant androgen profile in puberty compared with other children. Circulating androgen concentrations at 11–12 years of age were compared between offspring born after preeclampsia, and children whose mothers did not have preeclampsia.

Methods

A total of 611 mother-offspring pairs were followed up 11 (daughters) or 12 (sons) years after birth: 218 pairs in the preeclampsia group, and 383 pairs without preeclampsia. Circulating total testosterone, androstenedione, dehydroepiandrosterone sulfate (DHEAS), and insulin-like growth factor I (IGF-I) were measured in the children. In boys, testicular volume was also measured.

Results

Among girls born after preeclampsia, DHEAS concentrations were higher than in unexposed girls (p<0.001), however, girls born after preeclampsia with severe features had the lowest DHEAS levels. In contrast, testosterone concentrations were highest in girls born after preeclampsia with severe features, both compared to other girls in the preeclampsia group, and compared to unexposed girls (p<0.001). For boys, testosterone concentrations were higher in the preeclampsia group compared with unexposed boys (p<0.001), and boys born after preeclampsia with severe features had the lowest concentrations of DHEAS. Compared with unexposed boys, testicular volume (p = 0.015) and IGF-I (p = 0.004) were higher for boys in the preeclampsia group, except for boys in the clinically severe preeclampsia group.

Conclusions

In utero exposure to preeclampsia is associated with androgen hormonal patterns in early puberty that depend on clinical severity of preeclampsia and sex of the offspring. The hormonal differences may reflect different timing of pubertal development, and may have consequences for future health of the offspring.

Childhood adversity and depressive symptoms following retirement in the Gazel cohort

BACKGROUND

Only a few studies have examined whether specific moderators may impact the magnitude of the relationship between retirement and depression. The aim of this study was to examine the potential moderating role of adverse childhood life events (ACLE) on changes in depressive symptoms following retirement in the GAZEL cohort.

METHODS

9242 participants, followed up since 1989, completed the Center of Epidemiologic Studies Depression scale (CESD) every three years and were asked in 2004 to answer an ACLE questionnaire. Subjects were classed according to 6 clusters by Two-Step Cluster Analysis (no ACLE: cluster 1; increasing material deprivation: clusters 2 to 4; history of early separation: cluster 5 and history of conflicts or violence: cluster 6), and then stratified for sex. Analyses were based on general linear models with the CESD variation between, before and after retirement as dependent variable. All results were adjusted according to age, marital status, occupational status, alcohol consumption, self-rated health and CESD score before retirement.

RESULTS

The association between exposure to ACLE and changes in depressive symptoms following retirement was significant in both men (F = 6.929; p < 0.001; eta(2) = 0.005) and women (F = 6.890; p < 0.001; eta(2) = 0.016). Exposure to early separation or history of conflicts or violence during childhood was associated with less improvement in both men and women, whereas early exposure to material deprivation only affected results in men.

CONCLUSIONS

Programs aimed at facilitating retirement transition may focus on subjects at risk of not experiencing the expected benefits of retirement, which is the case for those with a history of ACLE.

Child Poverty and the Promise of Human Capacity: Childhood as a Foundation for Healthy Aging

The effect of child poverty and related early life experiences on adult health outcomes and patterns of aging has become a central focus of child health research and advocacy. In this article a critical review of this proliferating literature and its relevance to child health programs and policy are presented. This literature review focused on evidence of the influence of child poverty on the major contributors to adult morbidity and mortality in the United States, the mechanisms by which these associations operate, and the implications for reforming child health programs and policies. Strong and varied evidence base documents the effect of child poverty and related early life experiences and exposures on the major threats to adult health and healthy aging. Studies using a variety of methodologies, including longitudinal and cross-sectional strategies, have reported significant findings regarding cardiovascular disorders, obesity and diabetes, certain cancers, mental health conditions, osteoporosis and fractures, and possibly dementia. These relationships can operate through alterations in fetal and infant development, stress reactivity and inflammation, the development of adverse health behaviors, the conveyance of child chronic illness into adulthood, and inadequate access to effective interventions in childhood. Although the reviewed studies document meaningful relationships between child poverty and adult outcomes, they also reveal that poverty, experiences, and behaviors in adulthood make important contributions to adult health and aging. There is strong evidence that poverty in childhood contributes significantly to adult health. Changes in the content, financing, and advocacy of current child health programs will be required to address the childhood influences on adult health and disease. Policy reforms that reduce child poverty and mitigate its developmental effects must be integrated into broader initiatives and advocacy that also attend to the health and well-being of adults.

Early Trabecular Development in Human Vertebrae: Overproduction, Constructive Regression, and Refinement

Early bone development may have a significant impact upon bone health in adulthood. Bone mineral density (BMD) and bone mass are important determinants of adult bone strength. However, several studies have shown that BMD and bone mass decrease after birth. If early development is important for strength, why does this reduction occur? To investigate this, more data characterizing gestational, infant, and childhood bone development are needed in order to compare with adults. The aim of this study is to document early vertebral trabecular bone development, a key fragility fracture site, and infer whether this period is important for adult bone mass and structure. A series of 120 vertebrae aged between 6 months gestation and 2.5 years were visualized using microcomputed tomography. Spherical volumes of interest were defined, thresholded, and measured using 3D bone analysis software (BoneJ, Quant3D). The findings showed that gestation was characterized by increasing bone volume fraction whilst infancy was defined by significant bone loss (≈2/3rds) and the appearance of a highly anisotropic trabecular structure with a predominantly inferior-superior direction. Childhood development progressed via selective thickening of some trabeculae and the loss of others; maintaining bone volume whilst creating a more anisotropic structure. Overall, the pattern of vertebral development is one of gestational overproduction followed by infant "sculpting" of bone tissue during the first year of life (perhaps in order to regulate mineral homeostasis or to adapt to loading environment) and then subsequent refinement during early childhood. Comparison of early bone developmental data in this study with adult bone volume values taken from the literature shows that the loss in bone mass that occurs during the first year of life is never fully recovered. Early development could therefore be important for developing bone strength, but through structural changes in trabecular microarchitecture rather than bone mass.

Developmental programming by high fructose decreases phosphorylation efficiency in aging offspring brain mitochondria, correlating with enhanced UCP5 expression

Fructose has recently been observed to affect brain metabolism and cognitive function in adults. Yet, possible late-onset effects by gestational fructose exposure have not been examined. We evaluated mitochondrial function in the brain of aging (15 months) male offspring of Fischer F344 rat dams fed a high-fructose diet (50% energy from fructose) during gestation and lactation. Maternal fructose exposure caused a significantly lower body weight of the offspring throughout life after weaning, while birth weight, litter size, and body fat percentage were unaffected. Isolated brain mitochondria displayed a significantly increased state 3 respiration of 8%, with the substrate combinations malate/pyruvate, malate/pyruvate/succinate, and malate/pyruvate/succinate/rotenone, as well as a significant decrease in the P/O₂ ratio, compared with the control. Uncoupling protein 5 (UCP5) protein levels increased in the fructose group compared with the control (P=0.03) and both UCP5 mRNA and protein levels were inversely correlated with the P/O₂ ratio (P=0.008 and 0.03, respectively), suggesting that UCP5 may have a role in the observed decreased phosphorylation efficiency. In conclusion, maternal high-fructose diet during gestation and lactation has long-term effects (fetal programming) on brain mitochondrial function in aging rats, which appears to be linked to an increase in UCP5 protein levels.

Early-life nutritional programming of longevity

Available data from both experimental and epidemiological studies suggest that inadequate diet in early life can permanently change the structure and function of specific organs or homoeostatic pathways, thereby ‘programming’ the individual’s health status and longevity. Sufficient evidence has accumulated showing significant impact of epigenetic regulation mechanisms in nutritional programming phenomenon. The essential role of early-life diet in the development of aging-related chronic diseases is well established and described in many scientific publications. However, the programming effects on lifespan have not been extensively reviewed systematically. The aim of the review is to provide a summary of research findings and theoretical explanations that indicate that longevity can be influenced by early nutrition.

Maternal high-fat diet worsens memory deficits in the triple-transgenic (3xTgAD) mouse model of Alzheimer's disease

Alzheimer’s disease (AD) is not normally diagnosed until later in life, although evidence suggests that the disease starts at a much earlier age. Risk factors for AD, such as diabetes, hypertension and obesity, are known to have their affects during mid-life, though events very early in life, including maternal over-nutrition, can predispose offspring to develop these conditions. This study tested whether over-nutrition during pregnancy and lactation affected the development of AD in offspring, using a transgenic AD mouse model. Female triple-transgenic AD dam mice (3xTgAD) were exposed to a high-fat (60% energy from fat) or control diet during pregnancy and lactation. After weaning (at 3 weeks of age), female offspring were placed on a control diet and monitored up until 12 months of age during which time behavioural tests were performed. A transient increase in body weight was observed in 4-week-old offspring 3xTgAD mice from dams fed a high-fat diet. However, by 5 weeks of age the body weight of 3xTgAD mice from the maternal high-fat fed group was no different when compared to control-fed mice. A maternal high-fat diet led to a significant impairment in memory in 2- and 12-month-old 3xTgAD offspring mice when compared to offspring from control fed dams. These effects of a maternal high-fat diet on memory were accompanied by a significant increase (50%) in the number of tau positive neurones in the hippocampus. These data demonstrate that a high-fat diet during pregnancy and lactation increases memory impairments in female 3xTgAD mice and suggest that early life events during development might influence the onset and progression of AD later in life.

The impact of early life factors on cognitive function in old age: The Hordaland Health Study (HUSK)

Background

Previous studies have shown that adverse conditions during fetal and early life are associated with lower performance on neurocognitive tests in childhood, adolescence and adult life. There is, however, a paucity in studies investigating these associations into old age. The aim was to investigate the impact of early life factors on cognitive function in old age by taking advantage of the potential for a linkage between a community survey and historical birth records.

Methods

A historical cohort study employing a linkage between a community survey of people aged 72–74 years with the participants’ birth records (n=346). Early life factors included anthropometric measures taken at birth, birth complications, parental socioeconomic status, and maternal health status. The main outcome was a z-scored composite cognitive score, based on test scores from Kendrick Object Learning Test, Trail Making Test A, a modified version of the Digit Symbol Test, Block Design, a modified version of Mini-Mental State Examination and an abridged version of the Controlled Oral Word Association Test (COWAT). The separate cognitive tests were also individually analysed in relation to measures identified at birth.

Results

Higher parental socioeconomic status (SES; based on father’s occupation) was associated with a higher value on the composite cognitive score (by 0.25 SD, p=0.0146) and higher Digit Symbol and Trail Making Test A performance. Higher head circumference at birth was associated with higher COWAT and Trail Making Test A performance. Both higher parental SES and head circumference at birth predicted cognitive function in old age independently of each other. There were no other consistent associations.

Conclusions

In general we found little evidence for a substantial role of early life factors on late-life cognitive function. However, there was some evidence for an association with parental SES status and head circumference on certain cognitive domains.

Integrating risks for type 2 diabetes across childhood: a life course perspective

Type 2 diabetes (T2DM) emerged among children, due in large measure to a strong physiological link between increased weight states and T2DM. In this article, cumulative risk factors for T2DM across childhood and its underlying mechanisms are reviewed. The points of intervention for T2DM should occur throughout childhood. The use of Halfon and Hochstein's framework enables practitioners and researchers in the nursing field to better understand a child's individual risk for T2DM. Only with this long view will prevention and interventions be successful in stemming the tide of the "twin epidemic" threatening children worldwide.

Exposure to a maternal n-3 fatty acid-deficient diet during brain development provokes excessive hypothalamic-pituitary-adrenal axis responses to stress and behavioral indices of depression and anxiety in male rat offspring later in life

Brain docosahexaenoic acid (DHA, 22:6n-3) accumulates rapidly during brain development and is essential for normal neurological function. The aim of this study was to evaluate whether brain development was the critical period in which DHA deficiency leads to dysregulation of the hypothalamic-pituitary-adrenal (HPA) axis in response to stress later in life. Rats were exposed to an n-3 fatty acid-deficient diet or the same diet supplemented with fish oil as an n-3 fatty acid-adequate diet either throughout the preweaning period from embryo to weaning at 3 weeks old or during the postweaning period from 3 to 10 weeks old. Exposure to the n-3 fatty acid-deficient diet during the preweaning period resulted, at weaning, in a significant decrease in hypothalamic DHA levels and a reduced male offspring body weight. DHA deficiency during the preweaning period significantly increased and prolonged restraint stress-induced changes in colonic temperature and serum corticosterone levels, caused a significant increase in GABA(A) antagonist-induced heart rate changes and enhanced depressive-like behavior in the forced swimming test and anxiety-like behavior in the plus-maze test in later life. These effects were not seen in male rats fed the n-3 fatty acid-deficient diet during the postweaning period. These results suggest that brain development is the critical period in which DHA deficiency leads to excessive HPA responses to stress and elevated behavioral indices of depression and anxiety in adulthood. We propose that these effects of hypothalamic DHA deficiency during brain development may involve a GABA(A) receptor-mediated mechanism.

Developmental origins of adult diseases

There is considerable evidence for the fact that early life environment in human beings are associated with future development of various metabolic diseases. Fetal programming and perinatal events appear to exert effects on later life that are independent of environmental risk factors in adults. Our understanding of the underlying mechanisms are limited and remains unclear. However several animal models and epidemiological studies have shown this association, and it is assumed secondary to the penalties of developmental plasticity. In this review, we amalgamate facts from several disciplines to support this hypothesis.

Interrelationships of undernutrition and neurotoxicity: food for thought and research attention

The neurotoxic actions of chemical agents on humans and animals are usually studied with little consideration of the subject's nutritional status. States of protein-calorie, vitamin and/or mineral undernutrition are associated with a range of neurodevelopmental, neurological and psychiatric disorders, commonly with involvement of both the central and the peripheral nervous system. Undernutrition can modify risk for certain chemical-induced neurologic diseases, and in some cases undernutrition may be a prerequisite for neurotoxicity to surface. In addition, neurologic disease associated with undernutrition or neurotoxicity may show similarities in clinical and neuropathological expression, especially in the peripheral nervous system. The combined effects of undernutrition and chemical neurotoxicity are most relevant to people with low incomes who experience chronic hunger, parasitism and infectious disease, monotonous diets of plants with neurotoxic potential (notably cassava), environmental pollution from rapid industrial development, chronic alcohol abuse, or prolonged treatment with certain therapeutic drugs. Undernutrition alone or in combination with chemical exposure is also important in high-income societies in the setting of drug and alcohol abuse, old age, food faddism, post-bariatric surgery, and drug treatment for certain medical conditions, including cancer and tuberculosis. The nutritional demands of pregnancy and lactation increase the risk of fetal and infant undernutrition and chemical interactions therewith.

Insulin-like growth factor physiology: what we have learned from human studies

Although very similar to insulin and its receptor; the modus operandi of the insulin-like growth factors (IGFs) within the body is very different from that of the traditional peptide hormone. The IGF-binding proteins bind the IGFs with greater affinity than the cell surface receptors, enabling them to tightly control tissue activity. In addition to their role in fetal and childhood growth, IGFs play an important role in metabolic regulation. This article describes the basic underlying human physiology of IGFs, how this differs from that of experimental models, and why some information can only be learned from human clinical studies.

Development of fetal trabecular micro-architecture in the humerus and femur

It is widely accepted that during postnatal development trabecular bone adapts to the prevailing loading environment via modelling. However, very little is known about the mechanisms (whether it is predominantly modelling or remodelling) or controls (such as whether loading influences development) of fetal bone growth. In order to make inferences about these factors, we assessed the pattern of fetal trabecular development in the humerus and femur via histomorphometric parameter quantification. Growth and development (between 4 and 9 months prenatal) of trabecular architecture (i.e. thickness, number and bone volume fraction) was compared across upper and lower limb bones, proximal and distal regions, and sexes. The data presented here indicate that during prenatal development trabeculae became thicker and less numerous, whilst bone volume fraction remained constant. This partly mimics the pattern of early postnatal development (0-2 years) described by other researchers. Thickness was reported to increase whilst number reduced, but bone volume fraction decreased. This is perhaps because the balance of bone modelling (deposition vs. resorption) changes post partum. Published histological data suggest that bone deposition slows after birth, while resorption rates remain constant. Hence, fetal development may be characterized by relatively high rates of modelling and, particularly, bone deposition in comparison to postnatal. With respect to measures of thickness, number and bone volume fraction prenatal development was not bone, site, or sex specific, whilst postnatally these measures of architecture diverge. This is despite reported developmental variation in the frequency, speed and amplitude of fetal movements (which begin after 11 weeks and continue until birth), and probably therefore loading induced by muscular contractions. This may be because prenatal limb bone micro-architecture follows a generalised predetermined growth trajectory (or genetic blueprint), as appears to be the case for gross distribution of trabecular tissue.

Stress, glucocorticoids and liquorice in human pregnancy: programmers of the offspring brain

A suboptimal prenatal environment may induce permanent changes in cells, organs and physiology that alter social, emotional and cognitive functioning, and increase the risk of cardiometabolic and mental disorders in subsequent life ("developmental programming"). Although animal studies have provided a wealth of data on programming and its mechanisms, including on the role of stress and its glucocorticoid mediators, empirical evidence of these mechanisms in humans is still scanty. We review the existing human evidence on the effects of prenatal maternal stress, anxiety and depression, glucocorticoids and intake of liquorice (which inhibits the placental barrier to maternal glucocorticoids) on offspring developmental outcomes including, for instance, alterations in psychophysiological and neurocognitive functioning and mental health. This work lays the foundations for biomarker discovery and affords opportunities for prevention and interventions to ameliorate adverse outcomes in humans.

Association between birthweight and cognitive function in middle age: the atherosclerosis risk in communities study

PURPOSE

We aimed to examine the relationship of birthweight to cognitive performance in middle aged participants of the Atherosclerosis Risk in Communities Study (ARIC).

METHODS

Cognitive function, assessed by means of three neuropsychological tests-the Delayed Word Recall Test (DWR), the Digit Symbol Subtest of the Wechsler Adult Intelligence Scale-Revised (DSS/WAIS-R), and the Word Fluency (WF) Test, was evaluated in relation to birthweight, as recalled through standardized interviews, by the use of data from the second and fourth follow-up visits of the Atherosclerosis Risk in Communities study cohort (1990-1992 and 1996-1998, respectively). Overall, 6785 participants satisfied the inclusion criteria and were included in the analysis.

RESULTS

After adjusting for adult sociodemographic factors, childhood socioeconomic environment and parental risk factors, and adult anthropometric, health status-related. and behavioral variables, we observed linear trends for the relationship of birthweight to WF scores, although the trend was statistically significant only for those reporting exact birthweights (p for trend = .004). For the other cognitive test results, results were either null or inconsistent with the a priori hypotheses.

CONCLUSIONS

Except for WF in those reporting exact birthweights, our study does not support the notion that birthweight influences cognitive function in adults.

Birth weight and adult bone mass: a systematic literature review

SUMMARY

This systematic literature review comprised 16 studies. The association of birth weight with bone parameters was much more evident for bone mineral content (BMC) rather than bone mineral density (BMD). This is an important finding since a reduction in BMC is strongly associated with an increased risk of fractures.

INTRODUCTION

The purpose of this study was to conduct a systematic literature review of studies that have investigated the association between birth weight (BW) and adult bone mass.

METHODS

The search included English language articles, indexed in MEDLINE, using the key words: ("birth size" OR "birth weight" OR birthweight) AND (osteoporosis OR "bone mass" OR "bone density" OR "bone mineral density" OR "bone mineral content" OR "bone area"). A methodological quality appraisal of the reviewed studies was performed.

RESULTS

Sixteen articles were reviewed. Eleven of 13 studies that measured BMC verified a positive effect of BW on this parameter, and nine even after adjustment for adult body size. Among the ten studies that found an unadjusted association between BW and BMD, two reported that the significance remained after adjustment for current body size. Interaction between prenatal and postnatal variables on the determination of adult bone mass was only tested by two studies. The results must be interpreted with caution due to the existence of few papers on the issue, as well as heterogeneous sample characteristics, investigated bone sites, and implemented analysis procedures. The aspects of methodological quality that frequently fail are as follows: representativeness of the planned and actually measured sample as well as proper adjustment for confounding.

CONCLUSION

Based on the amount of accumulated evidence, it is probable that BW have a positive association with adult BMC rather than BMD, which is an important finding for clinical and public health policies since a reduction in BMC is strongly associated with an increased fracture risk.

Adults born at very low birth weight exercise less than their peers born at term

OBJECTIVE

To study the effects of very low birth weight (VLBW, <1500 g) birth on physical activity, an important protective and modifiable factor.

STUDY DESIGN

VLBW participants (n=163) with no major disability and 188 individuals born at term (mean age, 22.3 years; range, 18.5-27.1) completed a standardized questionnaire of physical activity.

RESULTS

VLBW participants reported less leisure-time conditioning physical activity. They were 1.61-fold more likely to "not exercise much," 1.61-fold more likely to exercise infrequently (once a week or less), 2.75-fold more likely to exercise with low intensity (walking), and 3.11-fold more likely to have short exercise sessions (<30 minutes). The differences were present even in subjects with no history of bronchopulmonary dysplasia or asthma and were only slightly attenuated when adjusted for height, parental education, lean body mass, and percent body fat.

CONCLUSIONS

Unimpaired adults who were VLBW exercise less during their leisure time than adults born at term. Promoting physical activity may be particularly important in the VLBW population to counteract the risks of chronic disease in adult life.

Birth weight and bone mass in young adults from Brazil

BACKGROUND

Birth weight is positively associated with adult bone mass. However, it is not clear if its effect is already evident in early adulthood.

OBJECTIVE

To investigate the association between birth weight, adult body size, the interaction between them and bone mass in young adults.

METHODS

Bone densitometry by DXA was performed on 496 individuals (240 men) aged 23-24 years from the 1978/79 Ribeirão Preto (southern Brazil) birth cohort, who were born and still residing in the city in 2002. Birth weight and length as well as adult weight and height were directly measured and converted to z-scores. The influence of birth weight and length, and adult weight and height on bone area (BA), bone mineral content (BMC) and bone mineral density (BMD) at the lumbar spine, proximal femur and femoral neck were investigated through simple and multiple linear regression models. Adjustments were made for sex, skin color, gestational age, physical activity level, smoking status and dietary consumption of protein, calcium and alcohol. Interaction terms between birth weight and adult weight, and birth length and adult height were tested.

RESULTS

Men in the highest tertile of birth weight distribution had greater BA and BMC at all three bone sites when compared with their counterparts in the lowest tertiles (p<0.008). For BMD, this trend was observed only in the lumbar spine. Adult weight and height were positively associated with BA and BMC at all three bone sites (p<0.05). For BMD, these associations were seen for adult weight, but for adult height an association was observed only in the lumbar spine. Birth weight retained positive associations with proximal femur BA and BMC after adjustments for current weight and height. No interaction was observed between variables measuring prenatal growth and adult body size.

CONCLUSION

Birth weight and postnatal growth are independent determinants of adult bone mass in a sample of Brazilian adults. This effect is already evident in early adulthood.

Behavioral changes in aging but not young mice after neonatal exposure to the polybrominated flame retardant decaBDE

BACKGROUND

After several decades of commercial use, the flame-retardant chemicals polybrominated diphenyl ethers (PBDEs) and their metabolites are pervasive environmental contaminants and are detected in the human body. Decabrominated diphenyl ether (decaBDE) is currently the only PBDE in production in the United States.

OBJECTIVES

Little is known about the health effects of decaBDE. In the present study we examined the effects of neonatal decaBDE exposure on behavior in mice at two ages.

METHODS

Neonatal male and female C57BL6/J mice were exposed to a daily oral dose of 0, 6, or 20 mg/kg decaBDE from postnatal days 2 through 15. Two age groups were examined: a cohort that began training during young adulthood and an aging cohort of littermates that began training at 16 months of age. Both cohorts were tested on a series of operant procedures that included a fixed-ratio 1 schedule of reinforcement, a fixed-interval (FI) 2-min schedule, and a light-dark visual discrimination.

RESULTS

We observed minimal effects on the light-dark discrimination in the young cohort, with no effects on the other tasks. The performance of the aging cohort was significantly affected by decaBDE. On the FI schedule, decaBDE exposure increased the overall response rate. On the light-dark discrimination, older treated mice learned the task more slowly, made fewer errors on the first-response choice of a trial but more perseverative errors after an initial error, and had lower latencies to respond compared with controls. Effects were observed in both dose groups and sexes on various measures.

CONCLUSIONS

These findings suggest that neonatal decaBDE exposure produces effects on behavioral tasks in older but not younger animals. The behavioral mechanisms responsible for the pattern of observed effects may include increased impulsivity, although further research is required.

Autism spectrum disorders in survivors of extreme prematurity

Recent studies in survivors of extreme prematurity point to an increased prevalence of a previously underrecognized atypical social-behavioral profile strongly suggestive of an autism spectrum disorder. Prospective studies that incorporate early autism screening and autism diagnostic testing are needed to better delineate the sensitivity and specificity of early signs of autism in ex-premature children. Advances in neonatal MRI techniques capable of quantitative structural and functional measurements will also provide important insights into the effects of prematurity itself, and prematurity-related brain injury on the genesis of autism spectrum disorders in this population. Available evidence linking prematurity and autism spectrum disorders is reviewed in this article.

Childhood socioeconomic status modifies the association between intellectual abilities at age 20 and mortality in later life

Background

People who score poorly in intellectual ability tests have shorter life expectancy. A study was undertaken to determine whether this association is different in people from different socioeconomic backgrounds.

Methods

The mortality of 2786 men born in Helsinki, Finland during 1934–1944 who, as military conscripts, underwent a standardised intellectual ability test comprising verbal, visuospatial and arithmetic reasoning subtests was studied. Mortality data came from the Finnish Death Register.

Results

Comparing men in the lowest and highest test score quartiles, HRs for all-cause mortality were 1.9 (95% CI 1.4 to 2.5) for verbal reasoning, 2.2 (95% CI 1.6 to 3.0) for visuospatial reasoning and 1.9 (95% CI 1.4 to 2.5) for arithmetic reasoning, corresponding to 2.6, 3.4 and 2.6 excess years of life lost, respectively. Associations were similar for cardiovascular and non-cardiovascular mortality. Intellectual ability scores were stronger predictors in men who grew up in middle-class families. Compared with middle-class men in the highest quartile of the visuospatial reasoning score, middle-class men in the lowest quartile lost 6.5 years of life while men from families of manual workers in the highest quartile lost 2.8 years and men in the lowest quartile lost 5.6 years.

Conclusions

High intellectual ability in men aged 20 protects them from mortality in later life. This effect is stronger in men who grew up in middle-class families than in those who grew up in manual worker families. This finding suggests that early life conditions that are unfavourable to the development of cognitive abilities negate the life expectancy benefits of being born into a more affluent family.