Head size and intelligence, learning, nutritional status and brain development

Physical growth and nonverbal intelligence: associations in Zambia

OBJECTIVE

To investigate normative developmental body mass index (BMI) trajectories and associations of physical growth indicators--height, weight, head circumference (HC), and BMI--with nonverbal intelligence in an understudied population of children from sub-Saharan Africa.

STUDY DESIGN

A sample of 3981 students (50.8% male), grades 3-7, with a mean age of 12.75 years was recruited from 34 rural Zambian schools. Children with low scores on vision and hearing screenings were excluded. Height, weight, and HC were measured, and nonverbal intelligence was assessed using the Universal Nonverbal Intelligence Test, Symbolic Memory subtest and Kaufman Assessment Battery for Children, Second Edition, Triangles subtest.

RESULTS

Students in higher grades had a higher BMI over and above the effect of age. Girls had a marginally higher BMI, although that for both boys and girls was approximately 1 SD below the international Centers for Disease Control and Prevention and World Health Organization norms. When controlling for the effect of age, nonverbal intelligence showed small but significant positive relationships with HC (r = 0.17) and BMI (r = 0.11). HC and BMI accounted for 1.9% of the variance in nonverbal intelligence, over and above the contribution of grade and sex.

CONCLUSION

BMI-for-age growth curves of Zambian children follow observed worldwide developmental trajectories. The positive relationships between BMI and intelligence underscore the importance of providing adequate nutritional and physical growth opportunities for children worldwide and in sub-Saharan Africa in particular. Directions for future studies are discussed with regard to maximizing the cognitive potential of all rural African children.

Diagnostic approach to microcephaly in childhood: a two-center study and review of the literature

AIM

The aim of this study was to assess the diagnostic approach to microcephaly in childhood and to identify the prevalence of the various underlying causes/disease entities.

METHOD

We conducted a retrospective study on a cohort of 680 children with microcephaly (399 males, 281 females; mean age at presentation 7-8mo, range 1mo-5y) from patients presenting to Charité - University Medicine Berlin (n=474) and University Hospital Dresden (n=206). Patient discharge letters were searched electronically to identify cases of microcephaly, and then the medical records of these patients were used to analyze parameters for distribution.

RESULTS

The putative aetiology for microcephaly was ascertained in 59% of all patients, leaving 41% without a definite diagnosis. In the cohort of pathogenetically defined microcephaly, genetic causes were identified in about half of the patients, perinatal brain damage accounted for 45%, and postnatal brain damage for 3% of the cases. Microcephaly was associated with intellectual impairment in 65% of participants, epilepsy was diagnosed in 43%, and ophthalmological disorders were found in 30%. Brain magnetic resonance imaging revealed abnormalities in 76% of participants.

INTERPRETATION

Microcephaly remains a poorly defined condition, and a uniform diagnostic approach is urgently needed. A definite aetiological diagnosis is important in order to predict the prognosis and offer genetic counselling. Identifying gene mutations as causes of microcephaly increases our knowledge of brain development and the clinical spectrum of microcephaly. We therefore propose a standardized initial diagnostic approach to microcephaly.

Brain development and scholastic achievement in the Education Quality Measurement System tests in Chilean school-aged children

BACKGROUND

Head circumference (HC), the anthropometric index of both brain development and nutritional background, has been described to be significantly associated with scholastic achievement (SA). The aim of this study was to determine the impact of nutritional background and current nutritional status parameters on SA in the Education Quality Measurement System (SIMCE) tests.

METHODS

A representative sample of 33 schools was randomly chosen in the Metropolitan Region of Chile. The sample consisted of 1,353 school-aged children of both sexes, from the fifth grade of elementary school and from the first grade of high school who in 2009 took the SIMCE tests. Nutritional status was assessed through anthropometric parameters. Brain development was measured through the HC expressed as HC-for-age Z-score (Z-HC).

RESULTS

Students with Z-HC < -2 SD and >2 SD obtained low and high SA, respectively, both in the language and the mathematics tests (P < 0.001). In general, in both grades, those students with Z-HC ≥ 0 SD increase more than double the probability to obtain language and mathematics SA scores ≥ the median (P < 0.0001).

CONCLUSION

We confirm the hypothesis that HC is the most relevant physical index associated with SA; therefore, children with the lowest scores in the SIMCE tests probably have lower brain development.

From foundling homes to day care: a historical review of childcare in Chile

This article discusses significant changes in childcare policy and practice in Chile. We distinguish four specific periods of childcare history: child abandonment and the creation of foundling homes in the 19th century; efforts to reduce infant mortality and the creation of the health care system in the first half of the 20th century; an increasing focus on inequality and poverty and the consequences for child development in the second half of the 20th century; and, finally, the current focus on children’s social and emotional development. It is concluded that, although Chile has achieved infant mortality and malnutrition rates comparable to those of developed countries, the country bears the mark of a history of inequality and is still unable to fully guarantee the health of children from the poorest sectors of society. Recent initiatives seek to improve this situation and put a strong emphasis on the psychosocial condition of children and their families.

Epigenetic analysis of neurocognitive development at 1 year of age in a community-based pregnancy cohort

Multiple studies show that molecular genetic changes and epigenetic modifications affect the risk of cognitive disability or impairment. However, the role of epigenetic variation in cognitive development of neurotypical young children remains largely unknown. Using data from a prospective, community-based study of mother-infant pairs, we investigated the association of DNA methylation patterns in neonatal umbilical cord blood with cognitive and language development at 1 year of age. No CpG loci achieved genome-wide significance, although a small number of weakly suggestive associations with Bayley-III Receptive Communication scales were noted. While umbilical cord blood is a convenient resource for genetic analyses of birth outcomes, our results do not provide conclusive evidence that its use for DNA methylation profiling yields epigenetic markers that are directly related to postnatal neurocognitive outcomes at 1 year of age.

The long-term cognitive consequences of early childhood malnutrition: the case of famine in Ghana

We examine the role of early childhood health in human capital accumulation. Using a unique data set from Ghana with comprehensive information on individual, family, community, school quality characteristics and a direct measure of intelligence together with test scores, we examine the long-term cognitive effects of the 1983 famine on survivors. We show that differences in intelligence test scores can be robustly explained by the differential impact of the famine in different parts of the country and the impacts are most severe for children under two years of age during the famine. We also account for model uncertainty by using Bayesian Model Averaging.

Clinical features, proximate causes, and consequences of active convulsive epilepsy in Africa

PURPOSE

Epilepsy is common in sub-Saharan Africa (SSA), but the clinical features and consequences are poorly characterized. Most studies are hospital-based, and few studies have compared different ecological sites in SSA. We described active convulsive epilepsy (ACE) identified in cross-sectional community-based surveys in SSA, to understand the proximate causes, features, and consequences.

METHODS

We performed a detailed clinical and neurophysiologic description of ACE cases identified from a community survey of 584,586 people using medical history, neurologic examination, and electroencephalography (EEG) data from five sites in Africa: South Africa; Tanzania; Uganda; Kenya; and Ghana. The cases were examined by clinicians to discover risk factors, clinical features, and consequences of epilepsy. We used logistic regression to determine the epilepsy factors associated with medical comorbidities.

KEY FINDINGS

Half (51%) of the 2,170 people with ACE were children and 69% of seizures began in childhood. Focal features (EEG, seizure types, and neurologic deficits) were present in 58% of ACE cases, and these varied significantly with site. Status epilepticus occurred in 25% of people with ACE. Only 36% received antiepileptic drugs (phenobarbital was the most common drug [95%]), and the proportion varied significantly with the site. Proximate causes of ACE were adverse perinatal events (11%) for onset of seizures before 18 years; and acute encephalopathy (10%) and head injury prior to seizure onset (3%). Important comorbidities were malnutrition (15%), cognitive impairment (23%), and neurologic deficits (15%). The consequences of ACE were burns (16%), head injuries (postseizure) (1%), lack of education (43%), and being unmarried (67%) or unemployed (57%) in adults, all significantly more common than in those without epilepsy.

SIGNIFICANCE

There were significant differences in the comorbidities across sites. Focal features are common in ACE, suggesting identifiable and preventable causes. Malnutrition and cognitive and neurologic deficits are common in people with ACE and should be integrated into the management of epilepsy in this region. Consequences of epilepsy such as burns, lack of education, poor marriage prospects, and unemployment need to be addressed.

Head circumference: the forgotten tool for hydrocephalus management. A reference interval study in the Spanish population

INTRODUCTION

In children, deviations from the normal range of head circumference (HC) have traditionally been related with CSF dynamics abnormalities. In adults, this neglected parameter is helpful in the diagnosis and understanding of the pathophysiology of some CSF abnormalities. It has been demonstrated that HC is related to height. Because humans have increased in stature dramatically during the last 50 years, pediatric charts for head growth physiology and normal HC values in adults should be reevaluated.

OBJECTIVES

The main aim of the present study was to assess HC in a series of 270 normal healthy Spanish adults and to determine any differences between sexes and age groups. A secondary aim was to discuss the relevance of this parameter in the management of hydrocephalus in adult people.

METHODS

HC measurements were taken using a measuring tape placed over the greatest frontal and occipital protuberances. The reference interval and the upper and lower thresholds for HC were calculated by 3 different methods: normal distribution, the non-parametrical percentile method, and the "robust method".

RESULTS

The results were consistent and showed that Spanish adult men with a HC greater than 60 cm, and Spanish adult women with a HC greater than 58 cm should be considered macrocephalic. Microcephaly should be considered when HC is 53.6 cm in men and 51.3 cm in women. Adult age groups of either sex do not present any statistically significant differences in HC.

CONCLUSIONS

HC obtained in Spanish adult people are greater than those reported in the classical Nellhaus graphs in both men and women aged 18. These findings should be considered in the management of hydrocephalus in adults today.

Head circumferences in twins with and without Autism Spectrum Disorders

To determine the genetic relationship between head circumference (HC) and Autism Spectrum Disorders (ASDs). Twin pairs with at least one twin with an ASD were assessed. HCs in affected and unaffected individuals were compared, as were HC correlations in monozygotic and dizygotic pairs. 404 subjects, ages 4-18, were included. 20 % of males and 27 % of females with an ASD had macrocephaly. Unaffected co-twins showed similar rates (16 % of males and 22 % of females). Statistical analysis revealed no significant difference in HCs between affected and unaffected twins. Twins with ASDs and unaffected co-twins have similar HCs and increased rates of macrocephaly. Correlations demonstrated partial inheritance of HCs. Thus, macrocephaly may represent an endophenotype in ASDs.

Defining pediatric malnutrition: a paradigm shift toward etiology-related definitions

Lack of a uniform definition is responsible for underrecognition of the prevalence of malnutrition and its impact on outcomes in children. A pediatric malnutrition definitions workgroup reviewed existing pediatric age group English-language literature from 1955 to 2011, for relevant references related to 5 domains of the definition of malnutrition that were a priori identified: anthropometric parameters, growth, chronicity of malnutrition, etiology and pathogenesis, and developmental/ functional outcomes. Based on available evidence and an iterative process to arrive at multidisciplinary consensus in the group, these domains were included in the overall construct of a new definition. Pediatric malnutrition (undernutrition) is defined as an imbalance between nutrient requirements and intake that results in cumulative deficits of energy, protein, or micronutrients that may negatively affect growth, development, and other relevant outcomes. A summary of the literature is presented and a new classification scheme is proposed that incorporates chronicity, etiology, mechanisms of nutrient imbalance, severity of malnutrition, and its impact on outcomes. Based on its etiology, malnutrition is either illness related (secondary to 1 or more diseases/injury) or non-illness related, (caused by environmental/behavioral factors), or both. Future research must focus on the relationship between inflammation and illness-related malnutrition. We anticipate that the definition of malnutrition will continue to evolve with improved understanding of the processes that lead to and complicate the treatment of this condition. A uniform definition should permit future research to focus on the impact of pediatric malnutrition on functional outcomes and help solidify the scientific basis for evidence-based nutrition practices.

Lack of severe long-term outcomes of acute, subclinical B1 deficiency in 216 children in Israel exposed in early infancy

BACKGROUND

A vitamin B(1)-deficient soy-based infant formula was marketed in Israel in 2003, exposing infants to clinical or subclinical B(1) deficiency. We investigated whether subclinical B(1) deficiency in early infancy had medical, neurodevelopmental, or cognitive effects at 3-5 y of age.

METHODS

A historical prospective cohort study was conducted consisting of four groups: "exposed," consuming a B(1)-deficient soy-based formula exclusively for four consecutive weeks or longer; "control," consuming no soy-based formula; "mixed," consuming the formula nonexclusively or exclusively for less than four consecutive weeks; and "other," consuming soy-based formulas other than Remedia. Participants were evaluated by medical examination, Stanford-Binet (SB) intelligence test, sensory profile evaluation, and Conners scales (attention deficit disorder/attention deficit and hyperactivity disorder (ADD/ADHD)).

RESULTS

Following adjustment for gender, age, and maternal education, there were no significant differences among the four groups on the mean SB scores, on the verbal and nonverbal scores, or in the proportion of children in each group with scores <90. A significantly higher proportion of exposed children as compared with control children had an impaired sensory profile and scores on the Conners scales (ADD/ADHD), but these proportions were also high in the "other" and "mixed" groups.

CONCLUSION

The results do not support an association between subclinical B(1) deficiency in infancy and long-term development.

Pesticide exposure and neurodevelopmental outcomes: review of the epidemiologic and animal studies

Assessment of whether pesticide exposure is associated with neurodevelopmental outcomes in children can best be addressed with a systematic review of both the human and animal peer-reviewed literature. This review analyzed epidemiologic studies testing the hypothesis that exposure to pesticides during pregnancy and/or early childhood is associated with neurodevelopmental outcomes in children. Studies that directly queried pesticide exposure (e.g., via questionnaire or interview) or measured pesticide or metabolite levels in biological specimens from study participants (e.g., blood, urine, etc.) or their immediate environment (e.g., personal air monitoring, home dust samples, etc.) were eligible for inclusion. Consistency, strength of association, and dose response were key elements of the framework utilized for evaluating epidemiologic studies. As a whole, the epidemiologic studies did not strongly implicate any particular pesticide as being causally related to adverse neurodevelopmental outcomes in infants and children. A few associations were unique for a health outcome and specific pesticide, and alternative hypotheses could not be ruled out. Our survey of the in vivo peer-reviewed published mammalian literature focused on effects of the specific active ingredient of pesticides on functional neurodevelopmental endpoints (i.e., behavior, neuropharmacology and neuropathology). In most cases, effects were noted at dose levels within the same order of magnitude or higher compared to the point of departure used for chronic risk assessments in the United States. Thus, although the published animal studies may have characterized potential neurodevelopmental outcomes using endpoints not required by guideline studies, the effects were generally observed at or above effect levels measured in repeated-dose toxicology studies submitted to the U.S. Environmental Protection Agency (EPA). Suggestions for improved exposure assessment in epidemiology studies and more effective and tiered approaches in animal testing are discussed.

Head circumference of infants born to mothers with different educational levels; the Generation R Study

OBJECTIVE

Head circumference (HC) reflect growth and development of the brain in early childhood. It is unknown whether socioeconomic differences in HC are present in early childhood. Therefore, we investigated the association between socioeconomic position (SEP) and HC in early childhood, and potential underlying factors.

METHODS

The study focused on Dutch children born between April 2002 and January 2006 who participated in The Generation R Study, a population-based prospective cohort study in Rotterdam, The Netherlands. Maternal educational level was used as indicator of SEP. HC measures were concentrated around 1, 3, 6 and 11 months. Associations and explanatory factors were investigated using linear regression analysis, adjusted for potential mediators.

RESULTS

The study included 3383 children. At 1, 3 and 6 months of age, children of mothers with a low education had a smaller HC than those with a high education (difference at 1 month: -0.42 SD; 95% CI: -0.54,-0.30; at 3 months: -0.27 SD; 95% CI -0.40,-0.15; and at 6 months: -0.13 SD; 95% CI -0.24,-0.02). Child's length and weight could only partially explain the smaller HC at 1 and 3 months of age. At 6 months, birth weight, gestational age and parental height explained the HC differences. At 11 months, no HC differences were found.

CONCLUSION

Educational inequalities in HC in the first 6 months of life can be mainly explained by pregnancy-related factors, such as birth weight and gestational age. These findings further support public health policies to prevent negative birth outcomes in lower socioeconomic groups.

Corporal punishment and youth externalizing behavior in Santiago, Chile

OBJECTIVES

Corporal punishment is still widely practiced around the globe, despite the large body of child development research that substantiates its short- and long-term consequences. Within this context, this paper examined the relationship between parental use of corporal punishment and youth externalizing behavior with a Chilean sample to add to the growing empirical evidence concerning the potential relationship between increased corporal punishment and undesirable youth outcomes across cultures.

METHODS

Analysis was based on 919 adolescents in Santiago, Chile. Descriptive and multivariate analyses were conducted to examine the extent to which parents' use of corporal punishment and positive family measures were associated with youth externalizing behavior. Furthermore, the associations between self-reported externalizing behavior and infrequent, as well as frequent, use of corporal punishment were investigated to understand how varying levels of parental use of corporal punishment were differently related to youth outcomes.

RESULTS

Both mothers' and fathers' use of corporal punishment were associated with greater youth externalizing behavior. Additionally, increases in positive parenting practices, such as parental warmth and family involvement, were met with decreases in youth externalizing behavior when controlling for youth demographics, family socioeconomic status, and parents' use of corporal punishment. Finally, both infrequent and frequent use of corporal punishment were positively associated with higher youth problem behaviors, though frequent corporal punishment had a stronger relationship with externalizing behavior than did infrequent corporal punishment.

CONCLUSIONS

Parental use of corporal punishment, even on an occasional basis, is associated with greater externalizing behavior for youth while a warm and involving family environment may protect youth from serious problem behaviors. Therefore, findings of this study add to the growing evidence concerning the negative consequences of corporal punishment for youth outcomes.

Common variants at 12q15 and 12q24 are associated with infant head circumference

To identify genetic variants associated with head circumference in infancy, we performed a meta-analysis of seven genome-wide association studies (GWAS) (N = 10,768 individuals of European ancestry enrolled in pregnancy and/or birth cohorts) and followed up three lead signals in six replication studies (combined N = 19,089). rs7980687 on chromosome 12q24 (P = 8.1 × 10(-9)) and rs1042725 on chromosome 12q15 (P = 2.8 × 10(-10)) were robustly associated with head circumference in infancy. Although these loci have previously been associated with adult height, their effects on infant head circumference were largely independent of height (P = 3.8 × 10(-7) for rs7980687 and P = 1.3 × 10(-7) for rs1042725 after adjustment for infant height). A third signal, rs11655470 on chromosome 17q21, showed suggestive evidence of association with head circumference (P = 3.9 × 10(-6)). SNPs correlated to the 17q21 signal have shown genome-wide association with adult intracranial volume, Parkinson's disease and other neurodegenerative diseases, indicating that a common genetic variant in this region might link early brain growth with neurological disease in later life.

External measures of cognition

The human brain is undoubtedly the most impressive, complex, and intricate organ that has evolved over time. It is also probably the least understood, and for that reason, the one that is currently attracting the most attention. In fact, the number of comparative analyses that focus on the evolution of brain size in Homo sapiens and other species has increased dramatically in recent years. In neuroscience, no other issue has generated so much interest and been the topic of so many heated debates as the difference in brain size between socially defined population groups, both its connotations and implications. For over a century, external measures of cognition have been related to intelligence. However, it is still unclear whether these measures actually correspond to cognitive abilities. In summary, this paper must be reviewed with this premise in mind.

Desenvolvimento cognitivo de prematuros à idade escolar: proposta de modelo hierarquizado para investigação dos fatores de risco

O déficit cognitivo é a sequela do neurodesenvolvimento mais prevalente na população de prematuros de muito baixo peso. Poucos são os trabalhos nacionais sobre o desenvolvimento desta população na idade escolar. Este estudo propõe uma discussão teórica sobre os fatores determinantes do desenvolvimento cognitivo na idade escolar de prematuros de muito baixo peso ao nascer, utilizando o modelo hierarquizado de análise. Neste modelo, fatores biológicos e ambientais se relacionariam em diversos níveis: distal, intermediário e proximal, resultando em alterações no desenvolvimento cognitivo. Pretende-se, desta forma, aprofundar a questão das mediações possíveis das variáveis e suas inter-relações e consequentes eventos que podem levar ao desfecho. Para a seleção dos fatores de risco foi realizada uma revisão da literatura sobre fatores associados a resultados cognitivos desfavoráveis. Pressupõe-se que o melhor conhecimento das inter-relações destes fatores auxiliaria na prevenção e intervenção mais adequada nesta população, aumentando suas chances de inclusão escolar e social.

Early postnatal blood concentrations of inflammation-related proteins and microcephaly two years later in infants born before the 28th post-menstrual week

BACKGROUND

To evaluate if concentrations of inflammation-related proteins were elevated in early postnatal blood specimens of preterm newborns who two years later had a small head.

METHODS

We measured 25 proteins in blood collected on days 1, 7, and 14 from 839 infants born before the 28th week of gestation and whose head circumference was measured at birth and near 24-months post-term equivalent. We excluded children whose birth head circumference was at or below the third centile. A protein concentration was considered elevated if it was in the highest quartile for gestational age and the day the specimen was obtained.

FINDINGS

When proteins were evaluated individually, elevated concentrations of SAA on day 1 and five proteins on day 14, IL-6, TNF-R2, IL-8, MCP-1, and ICAM-1 were associated with significantly increased risk of microcephaly (head circumference Z-score <-2). The ten proteins whose elevated concentrations on two separate days a week apart predicted microcephaly, but did not do so when elevated on only one of these days were CRP, SAA, IL-1β, IL-6, TNF-α, IL-8, MCP-1, ICAM-1, E-SEL, IGFBP-1. Elevated protein concentrations weakly predicted a less severe reduction in head circumference (Z-score ≥ -2, < -1).

INTERPRETATION

Concentrations of inflammation-related proteins in the circulation shortly after preterm birth provide information about the risk of a reduced head circumference more than two years later.

FUNDING

The ELGAN Study was supported by a cooperative agreement with the National Institute of Neurological Disorders and Stroke of the United States.

Adaptation, expertise, and giftedness: towards an understanding of cortical, subcortical, and cerebellar network contributions

Current cortico-centric models of cognition lack a cohesive neuroanatomic framework that sufficiently considers overlapping levels of function, from "pathological" through "normal" to "gifted" or exceptional ability. While most cognitive theories presume an evolutionary context, few actively consider the process of adaptation, including concepts of neurodevelopment. Further, the frequent co-occurrence of "gifted" and "pathological" function is difficult to explain from a cortico-centric point of view. This comprehensive review paper proposes a framework that includes the brain's vertical organization and considers "giftedness" from an evolutionary and neurodevelopmental vantage point. We begin by discussing the current cortico-centric model of cognition and its relationship to intelligence. We then review an integrated, dual-tiered model of cognition that better explains the process of adaptation by simultaneously allowing for both stimulus-based processing and higher-order cognitive control. We consider the role of the basal ganglia within this model, particularly in relation to reward circuitry and instrumental learning. We review the important role of white matter tracts in relation to speed of adaptation and development of behavioral mastery. We examine the cerebellum's critical role in behavioral refinement and in cognitive and behavioral automation, particularly in relation to expertise and giftedness. We conclude this integrated model of brain function by considering the savant syndrome, which we believe is best understood within the context of a dual-tiered model of cognition that allows for automaticity in adaptation as well as higher-order executive control.

Heritability of head size in Dutch and Australian twin families at ages 0-50 years

We assessed the heritability of head circumference, an approximation of brain size, in twin-sib families of different ages. Data from the youngest participants were collected a few weeks after birth and from the oldest participants around age 50 years. In nearly all age groups the largest part of the variation in head circumference was explained by genetic differences. Heritability estimates were 90% in young infants (4 to 5 months), 85-88% in early childhood, 83-87% in adolescence, 75% in young and mid adulthood. In infants younger than 3 months, heritability was very low or absent. Quantitative sex differences in heritability were observed in 15- and 18-year-olds, but there was no evidence for qualitative sex differences, that is, the same genes were expressed in both males and females. Longitudinal analysis of the data between 5, 7, and 18 years of age showed high genetic stability (.78 > R(G) > .98). These results indicate that head circumference is a highly heritable biometric trait and a valid target for future GWA studies.

Early cranial ultrasound lesions predict microcephaly at age 2 years in preterm infants

To assess how well early ultrasound lesions in preterm newborns predict reduced head circumference at 2 years, the investigators followed 923 children born before the 28th week of gestation who were not microcephalic at birth. Six percent of children who had a normal ultrasound scan were microcephalic compared with 15% to 20% who had intraventricular hemorrhage, an echolucent lesion, or ventriculomegaly. The odds ratios (95% confidence intervals) for microcephaly associated with different ultrasound images were intraventricular hemorrhage, 1.5 (0.8-3.0); ventriculomegaly, 3.3 (1.8-6.0); an echodense lesion, 1.6 (0.7-3.5); and an echolucent lesion, 3.1 (1.5-6.2). Ventriculomegaly and an echolucent lesion had very similar low positive predictive values (24% and 27%, respectively) and high negative predictive values (91% and 90%, respectively) for microcephaly. Ventriculomegaly had a higher sensitivity for microcephaly than did an echolucent lesion (24% vs 16%, respectively). Focal white-matter lesion (echolucent lesion) and diffuse white-matter damage (ventriculomegaly) predict an increased risk of microcephaly.

Neural precursor cell proliferation is disrupted through activation of the aryl hydrocarbon receptor by 2,3,7,8-tetrachlorodibenzo-p-dioxin

Neurogenesis involves the proliferation of multipotent neuroepithelial stem cells followed by differentiation into lineage-restricted neural precursor cells (NPCs) during the embryonic period. Interestingly, these progenitor cells express robust levels of the aryl hydrocarbon receptor (AhR), a ligand-activated transcription factor that regulates expression of genes important for growth regulation, and xenobiotic metabolism. Upon binding 2,3,7,8-tetrachlorodibenzo-p-dioxin (TCDD), a pervasive environmental contaminant and potent AhR ligand, AhR, is activated and disrupts gene expression patterns to produce cellular toxicity. Because of its widespread distribution in the brain during critical proliferative phases of neurogenesis, it is conceivable that AhR participates in NPC expansion. Therefore, this study tested the hypothesis that AhR activation by TCDD disrupts signaling events that regulate NPC proliferation. The C17.2 NPC line served as a model system to (1) assess whether NPCs are targets for TCDD-induced neurotoxicity and (2) characterize the effects of TCDD on NPC proliferation. We demonstrated that C17.2 NPCs express an intact AhR signaling pathway that becomes transcriptionally active after TCDD exposure. (3)H-thymidine and alamar blue reduction assays indicated that TCDD suppresses NPC proliferation in a concentration-dependent manner without the loss of cell viability. Cell cycle distribution analysis by flow cytometry revealed that TCDD-induced growth arrest results from an impaired G1 to S cell cycle transition. Moreover, TCDD exposure altered p27( kip1) and cyclin D1 cell cycle regulatory protein expression levels consistent with a G1 phase arrest. Initial studies in primary NPCs isolated from the ventral forebrain of embryonic mice demonstrated that TCDD reduced cell proliferation through a G1 phase arrest, corroborating our findings in the C17.2 cell line. Together, these observations suggest that the inappropriate or sustained activation of AhR by TCDD during neurogenesis can interfere with signaling pathways that regulate neuroepithelial stem cell/NPC proliferation, which could adversely impact final cell number in the brain and lead to functional impairments.

Brain anatomical network and intelligence

Intuitively, higher intelligence might be assumed to correspond to more efficient information transfer in the brain, but no direct evidence has been reported from the perspective of brain networks. In this study, we performed extensive analyses to test the hypothesis that individual differences in intelligence are associated with brain structural organization, and in particular that higher scores on intelligence tests are related to greater global efficiency of the brain anatomical network. We constructed binary and weighted brain anatomical networks in each of 79 healthy young adults utilizing diffusion tensor tractography and calculated topological properties of the networks using a graph theoretical method. Based on their IQ test scores, all subjects were divided into general and high intelligence groups and significantly higher global efficiencies were found in the networks of the latter group. Moreover, we showed significant correlations between IQ scores and network properties across all subjects while controlling for age and gender. Specifically, higher intelligence scores corresponded to a shorter characteristic path length and a higher global efficiency of the networks, indicating a more efficient parallel information transfer in the brain. The results were consistently observed not only in the binary but also in the weighted networks, which together provide convergent evidence for our hypothesis. Our findings suggest that the efficiency of brain structural organization may be an important biological basis for intelligence.

Networks of interconnected brain regions coordinate brain activities. Information is processed in the grey matter (cortex and subcortical structures) and passed along the network via whitish, fatty-coated fiber bundles, the white matter. Using maps of these white matter tracks, we provided evidence that higher intelligence may result from more efficient information transfer. Specifically, we hypothesized that higher IQ derives from higher global efficiency of the brain anatomical network. Seventy-nine healthy young adults were divided into general and high IQ groups. We used diffusion tensor tractography, which maps brain white matter fibers, to construct anatomical brain networks for each subject and calculated the network properties using both binary and weighted networks. We consistently found that the high intelligence group's brain network was significantly more efficient than was the general intelligence group's. Moreover, IQ scores were significantly correlated with network properties, such as shorter path lengths and higher overall efficiency, indicating that the information transfer in the brain was more efficient. These converging evidences support the hypothesis that the efficiency of the organization of the brain structure may be an important biological basis for intelligence.

Impact of nutritional status at the onset of elementary school on academic aptitude test achievement at the end of high school in a multicausal approach

Like in many other countries, few investigations have been carried out in Chile to measure the long-term effects of nutritional status at an early age on scholastic achievement in a multicausal approach. The objectives of the present study were to describe the impact of nutritional, intellectual, family, educational and socio-economic variables at the onset of elementary school in 1987 that may affect achievement on the academic aptitude test (AAT) taken in 1998 at the end of high school, and to quantify the impact of these independent variables on the AAT. The present study comprises two cross-sectional stages: in 1987, a representative sample of 813 elementary school first-grader Chilean children from the Metropolitan Region was randomly chosen; in 1998, 12 years later, 632 school-age children were located and only 351 of them graduated from high school and, from these, 260 students took the AAT. In 1987 nutritional status was assessed through anthropometric parameters, intellectual ability by the Raven's Progressive Matrices Test, scholastic achievement through Spanish language and mathematics tests, and socio-economic status using Graffar's modified scale; family variables were also recorded. Maternal schooling, scholastic achievement, intellectual ability and head circumference-for-age z-score (anthropometric indicator of both nutritional background and brain development) all in 1987 were the independent variables with the greatest explanatory power for AAT variance in 1998 (r2 0·402). These results provide a foundation to identify the risk factors at an early age that affect AAT scores and should be useful to improve nutritional and educational policies.

Postdischarge growth and development in a predominantly Hispanic, very low birth weight population

OBJECTIVES

The goals were to assess postdischarge growth and developmental progress of very low birth weight (birth weight: <1500 g) premature infants in a predominantly Hispanic population and to identify predictors for neurodevelopmental impairment at 3 years of age.

METHODS

A cohort of 135 very low birth weight infants (gestational age: 23 to 35 weeks) were monitored to 3 years of age. Maternal and neonatal characteristics, anthropometric z scores, and developmental performance (using corrected age until 24 months) were analyzed collectively and according to gestational age groups. Specific criteria for failure to thrive and microcephaly were used.

RESULTS

A characteristic pattern of poor weight gain in the first 12 months was followed by accelerated weight gain starting at 18 months, whereas head growth decreased at 18 months, with recovery beginning at 30 months of age. Infants born at gestational age of <or=26 weeks remained growth-impaired at 3 years of age, whereas infants born at gestational age of >or=27 weeks achieved catch-up growth by 30 months of age. Mean developmental scores also decreased in infancy, with improvements in motor development emerging at 18 months and cognitive skills at 30 months. Growth z scores, particularly for head growth, correlated with developmental scores. Infants born at gestational age of <or=26 weeks were most likely to have neonatal morbidities, failure to thrive, and neurodevelopmental impairment. With adjustment for gestational age and neonatal morbidities, Hispanic acculturation, failure to thrive, and microcephaly were predictive of neurodevelopmental impairment.

CONCLUSIONS

Very low birth weight infants exhibited growth patterns that coincided with developmental progress in the first 3 years of life. Birth at gestational age of <or=26 weeks was associated with greatest risk for developmental impairment, whereas failure to thrive and microcephaly increased neurodevelopmental impairment risk regardless of gestational age.

Is sub-nutrition necessary for a poor outcome following early institutional deprivation?

Institutional deprivation is multifaceted and includes adverse psychosocial and nutrition-related components. In this study we partitioned these risks in relation to cognitive impairment and mental ill health, and explored the mediating role of reduced head/brain size. There were 138 participants (61 males, 77 females) in the study. Participants were Romanian adoptees who had experienced at least 2 weeks of early institutional deprivation. The sample was stratified on the basis of duration of deprivation (high risk >6 mo in institutions) and sub-nutrition (i.e. 1.5 SD below UK age-related norms for weight at UK entry). UK children adopted before 6 months of age and a group of non-institutionally deprived Romanian children constituted the comparison groups. Duration of deprivation was associated with smaller head circumference, lowered IQ, and increased mental heath problems, independently of effects found for sub-nutrition on head circumference and IQ. The mediating role of head circumference was limited to either sub-nourished (IQ) or non-sub-nourished (inattention/overactivity and disinhibited attachment) subgroups. Many negative effects of early deprivation, including stunted brain growth, occur without sub-nutrition: psychosocial deprivation plays a major role in neurodevelopmental effects of deprivation. Further studies of functional and structural neuroanatomy following institutional deprivation are required to delineate the role of brain development in its effects.

Socioeconomic status, anthropometric status, and psychomotor development of Kenyan children from resource-limited settings: a path-analytic study

BACKGROUND

Sub-optimal physical growth has been suggested as a key pathway between the effect of environmental risk and developmental outcome.

AIM

To determine if anthropometric status mediates the relation between socioeconomic status and psychomotor development of young children in resource-limited settings.

STUDY DESIGN

A cross-sectional study design was used.

SUBJECTS

A total of 204 (105 girls) children from two resource-limited communities in the Coast Province, Kenya. The mean age of these children was 29 months (SD = 3.43; range: 24-35 months).

OUTCOME MEASURE

Psychomotor functioning was assessed using a locally developed and validated measure, the Kilifi Developmental Inventory.

RESULTS

A significant association was found between anthropometric status (as measured by weight-for-age, height-for-age, mid-upper arm circumference, and head circumference) and psychomotor functioning and also between socioeconomic status and anthropometric status; no direct effects were found between socioeconomic status and developmental outcome. The models showed that weight, height and to a lesser extent mid-upper arm circumference mediate the relation between socioeconomic status and developmental outcome, while head circumference did not show the same effect.

CONCLUSION

Among children under 3 years living in poverty, anthropometric status shows a clear association with psychomotor development while socioeconomic status may only have an indirect association.

Association of birth outcomes and maternal, school, and neighborhood characteristics with subsequent numeracy achievement

This study investigated the relation between birth characteristics and numeracy attainment at age 8 years. Using a multilevel approach, the authors analyzed all non-Aboriginal singletons born in Western Australia who attended government schools and participated in a Western Australia-wide numeracy test in grade 3 between 1999 and 2005. Appropriateness of intrauterine growth was expressed as the proportion of optimal growth parameters for gestational duration, infant sex, and maternal height and parity, which was derived from a total population of births without risk factors for growth restriction. After the authors controlled for sociodemographic factors, term birth and proportion of optimal head circumference at birth were associated with higher numeracy scores. Increasing proportion of optimal birth length and being firstborn were associated with relatively higher numeracy scores among children born to mothers residing in the most educationally deprived area. The relative advantage of being born first was also higher for children born to single mothers. In contrast, higher Apgar scores and greater proportion of optimal birth weight were associated with a lower relative advantage for children born to single mothers. In summary, term birth and increased growth in head circumference and length are key birth characteristics associated with higher numeracy scores, especially among disadvantaged children.

White matter tract integrity and intelligence in patients with mental retardation and healthy adults

It is well known that brain structures correlate with intelligence but the association between the integrity of brain white matter tracts and intelligence in patients with mental retardation (MR) and healthy adults remains unknown. The aims of this study are to investigate whether the integrity of corpus callosum (CC), cingulum, uncinate fasciculus (UF), optic radiation (OR) and corticospinal tract (CST) are damaged in patients with MR, and to determine the correlations between the integrity of these tracts and full scale intelligence quotient (FSIQ) in both patients and controls. Fifteen MR patients and 79 healthy controls underwent intelligence tests and diffusion tensor imaging examinations. According to the FSIQ, all healthy controls were divided into general intelligence (GI: FSIQ<120; n=42) and high intelligence (HI: FSIQ> or =120; n=37) groups. Intelligence was assessed by Chinese Revised Wechsler Adult Intelligence Scale, and white matter tract integrity was assessed by fractional anisotropy (FA). MR patients showed significantly lower FA than healthy controls in the CC, UF, OR and CST. However, GI subjects only demonstrated lower FA than HI subjects in the right UF. Partial correlation analysis controlling for age and sex showed that FSIQ scores were significantly correlated with the FA of the bilateral UF, genu and truncus of CC, bilateral OR and left CST. While FSIQ scores were only significantly correlated with the FA of the right UF when further controlling for group. This study indicate that MR patients show extensive damage in the integrity of the brain white matter tracts, and the right UF is an important neural basis of human intelligence.

Hippocampal size positively correlates with verbal IQ in male children

Historically, there have been numerous proposals that the size of the brain correlates with its capacity to process information. Little is known, however, about which specific brain regions contribute to this correlation in children and adolescents. This study evaluated the relationship between intelligence and the size of various brain structures in typically developing male children 8-18 yrs of age. Magnetic resonance imaging (MRI) scans were used to measure the volume of the cerebrum, cerebral gray and white matter, cerebellum, amygdala, and hippocampus. Gray matter and hippocampal volume significantly correlated with full scale and verbal IQ. Since the hippocampus strongly correlated with verbal but not performance IQ, our findings reinforce the hypothesis that the hippocampus is involved in declarative and semantic learning, which contributes more notably to verbal IQ, than to performance IQ. Given the substantial evidence for environmentally induced changes in hippocampal structure, an unresolved issue is whether this relationship reflects genetically determined individual variation or learning induced plasticity.

Plasticity of growth in height, weight, and head circumference: meta-analytic evidence of massive catch-up after international adoption

Are serious growth delays caused by malnutrition and neglect permanent or reversible? The effects of institutionalization and international adoption on children's physical growth are estimated with meta-analysis. Studies with sufficient data to compute differences between adoptees and the reference population (33 papers with 122 study outcomes) were collected through Web of Science, ERIC (Education Resource Information Center), PsycINFO (Psychological Literature), and Medline (U.S. National Library of Medicine) (1956-2006). The influence of pre- and postadoption care on height, weight, and head circumference was tested. Effect sizes (d) and confidence intervals (CIs) around the point estimate for the growth lag indices were computed. The more time spent in institutional care, the more the children lagged behind in physical growth (d = 1.71, 95% CI: 0.82-2.60, n = 893). At adoptive placement, the children showed large delays in height, weight, and head circumference (d = -2.39 to -2.60; n = 1331-3753). Although after adoption, they showed almost complete catch-up of height (d = -0.57, 95% CI: -0.87 to -0.27, n = 3437 adoptees) and weight (d = -0.72, 95% CI: -1.04 to -0,39, n = 3259 adoptees), catch-up of head circumference seemed slower and remained incomplete (d = -1.56, 95% CI: -2.27 to -0.85, n = 527). Later age at arrival was related to less complete catch-up of height and weight. International adoption leads to substantial catch-up of height and weight but not of head circumference, demonstrating differential plasticity of children's physical growth.

Aortic morphometry and microcephaly in hypoplastic left heart syndrome

Microcephaly is a marker of abnormal fetal cerebral development, and a known risk factor for cognitive dysfunction. Patients with hypoplastic left heart syndrome have been found to have an increased incidence of abnormal neurodevelopmental outcomes. We hypothesized that reduced cerebral blood flow from the diminutive ascending aorta and transverse aortic arch in the setting of hypoplastic left heart syndrome may influence fetal growth of the brain. The purpose of our study, therefore, was to define the prevalence of microcephaly in full-term infants with hypoplastic left heart syndrome, and to investigate potential cardiac risk factors for microcephaly. We carried out a retrospective review of full-term neonates with hypoplastic left heart syndrome. Eligible patients had documented indexes of birth weight, and measurements of length, and head circumference, as well as adequate echocardiographic images for measurement of the diameters of the ascending aorta and transverse aortic arch. We used logistic regression for analysis of the data. A total of 129 neonates met the criteria for inclusion, with 15 (12%) proving to have microcephaly. The sizes of their heads were disproportionately smaller than their weights (p less than 0.001) and lengths (p less than 0.001) at birth. Microcephaly was associated with lower birth weight (p less than 0.001), lower birth length (p equal to 0.007), and a smaller diameter of the ascending aorta (p equal to 0.034), but not a smaller transverse aortic arch (p equal to 0.619), or aortic atresia (p equal to 0.969). We conclude that microcephaly was common in this cohort of neonates with hypoplastic left heart syndrome, with the size of the head being disproportionately smaller than weight and length at birth. Microcephaly was associated with a small ascending aorta, but not a small transverse aortic arch. Impairment of somatic growth may be an additional factor in the development of microcephaly in these neonates.

Twelve-year follow-up study of the impact of nutritional status at the onset of elementary school on later educational situation of Chilean school-age children

OBJECTIVE

To determine the impact of nutritional status in a multicausal approach of socio-economic, socio-cultural, family, intellectual, educational and demographic variables at the onset of elementary school in 1987 on the educational situation of these children in 1998, when they should have graduated from high school.

SETTING

Chile's Metropolitan Region.

DESIGN

Prospective, observational and 12-year follow-up study.

METHODS

A representative sample of 813 elementary first grade school-age children was randomly chosen in 1987. The sample was assessed in two cross-sectional studies. The first cross-sectional study was carried out in at the onset of elementary school in 1987 and the second was carried out in 1998, 12-years later, when they should be graduating from high school. In 1998, 632 adolescent students were located and their educational situation was registered (dropout, delayed, graduated and not located). At the onset of elementary school were determined the nutritional status, socio-economic status (SES), family characteristics, intellectual ability (IA), scholastic achievement (SA) and demographic variables. Statistical analysis included variance tests and Scheffe's test was used for comparison of means. Pearson correlation coefficients and logistic regression were used to establish the most important independent variables at the onset of elementary school in 1987 that affect the educational situation 1998. Data were analysed using the statistical analysis system (SAS).

RESULTS

Logistic regression revealed that SES, IA, SA and head circumference-for-age Z score at the onset of elementary school in 1987 were the independent variables with the greatest explanatory power in the educational situation of school-age children in 1998.

CONCLUSIONS

These parameters at an early school age are good predictors of the educational situation later and these results can be useful for nutrition and educational planning in early childhood.

Do the Effects of Early Severe Deprivation on Cognition Persist Into Early Adolescence? Findings From the English and Romanian Adoptees Study

Cognitive outcomes at age 11 of 131 Romanian adoptees from institutions were compared with 50 U.K. adopted children. Key findings were of both continuity and change: (1) marked adverse effects persisted at age 11 for many of the children who were over 6 months on arrival; (2) there was some catch-up between ages 6 and 11 for the bottom 15%; (3) there was a decrease of 15 points for those over 6 months on arrival, but no differentiation within the 6-42-month range; (4) there was marked heterogeneity of outcome but this was not associated with the educational background of the adoptive families. The findings draw attention to the psychological as well as physical risks of institutional deprivation.

Bridges over troubled waters: education and cognitive neuroscience

Recently there has been growing interest in and debate about the relation between cognitive neuroscience and education. Our goal is to advance the debate beyond both recitation of potentially education-related cognitive neuroscience findings and the claim that a bridge between fields is chimerical. In an attempt to begin a dialogue about mechanisms among students, educators, researchers and practitioner-scientists, we propose that multiple bridges can be built to make connections between education and cognitive neuroscience, including teacher training, researcher training and collaboration. These bridges--concrete mechanisms that can advance the study of mind, brain and education--will benefit both educators and cognitive neuroscientists, who will gain new perspectives for posing and answering crucial questions about the learning brain.

Birth characteristics and risk of low intellectual performance in early adulthood: are the associations confounded by socioeconomic factors in adolescence or familial effects?

OBJECTIVE

In this study we investigated whether the association between measures of fetal growth restriction and intellectual performance was mediated by socioeconomic or familial factors.

METHODS

This was a population-based cohort study of 357,768 Swedish males born as singletons without congenital malformations between 1973 and 1981. The main outcome measure was intellectual performance at military conscription.

RESULTS

Compared with men born with appropriate birth weight for gestational age, men born light for gestational age suffered an increased risk of low intellectual performance after adjustment for maternal and socioeconomic factors. The increase in risk of low intellectual performance related to a decrease in birth weight for gestational age was similar between families and within families. Men born short or with a small head circumference for gestational age were also at increased risk of low intellectual performance, both when adjusting for maternal and socioeconomic factors and within families.

CONCLUSIONS

We found that all of the studied dimensions of restricted fetal growth are independently associated with increased risks of low intellectual performance and that these associations are only partly mediated by socioeconomic or familial factors.

Parental IQ and cognitive development of malnourished Indonesian children

A cross-sectional study of children in West Kalimantan, Indonesia, was conducted to examine the relationship between malnutrition history, child IQ, school attendance, socioeconomic status, parental education and parental IQ. In unadjusted analyses, severely stunted children had significantly lower IQ scores than mild-moderately stunted children. This effect was significant when stunting, school attendance and parental education were included in multivariable models but was attenuated when parental IQ was included. Our research underscores the importance of accounting for parental IQ as a critical covariate when modeling the association between childhood stunting and IQ.

Scholastic achievement: a multivariate analysis of nutritional, intellectual, socioeconomic, sociocultural, familial, and demographic variables in Chilean school-age children

OBJECTIVE

We determined relative effects of nutritional status, intellectual ability, exposure to mass media, and socioeconomic, sociocultural, familial, demographic, and educational variables on scholastic achievement (SA).

METHODS

This was a cross-sectional study. Exposure to mass media and nutritional, intellectual, socioeconomic, sociocultural, familial, demographic, and educational factors, including approximately 2000 variables, were measured in a representative and proportional sample of 4509 school-age children from elementary and high schools in Chile's Metropolitan Region. The field study was carried out between 1986 and 1987, and data processing, which lasted 15 y, was completed in 2002.

RESULTS

Within the total sample, intellectual ability, level of maternal schooling, head circumference-for-age Z score, book reading, in-door plumbing, level of paternal schooling, type of school, quality of housing, height-for-age Z score, and calcium intake were the independent variables with the greatest explanatory power in SA variance (r(2) = 0.508). In most grades, IA was the independent variable with the greatest explanatory power in SA variance. In adolescents in their fourth year of high school and whose physical growth and intellectual development processes are consolidated, intellectual ability, age, head circumference-for-age Z score, book reading, type of school, and level of paternal schooling were the independent variables with the greatest explanatory power in SA variance (r(2) = 0.60).

CONCLUSIONS

These findings show that SA is conditioned by multiple factors depending on the characteristics of school-age children, their families, and the educational system. Nutritional indicators of past nutrition are significantly associated with SA, especially head circumference-for-age Z score. This information may be useful for health and educational planning.

Developmental, cognitive, and neuropsychological functioning in preschool-aged foster children: associations with prior maltreatment and placement history

Although young children in foster care are at high risk for developmental delays and subsequent academic, social, and behavioral difficulties, many do not receive services for delays. We sought to explicate the types of developmental delays observed in young children (ages 3-6 years) in foster care and how placement and maltreatment experiences for these children were associated with such delays. Physical growth, neuropsychological functioning, executive functioning, language, and general cognitive functioning were compared for a sample of 99 foster children and 54 nonmaltreated, same-aged children from comparable socioeconomic status backgrounds. The foster children showed developmental lags on measures of height, head circumference, visuospatial functioning, language, and general cognitive functioning. A history of neglect was negatively associated with functioning in a number of domains; surprisingly, the number of maltreatment types experienced was positively associated with functioning. Placement history was generally not associated with scores in the various developmental domains. We discuss the need to screen and evaluate preschoolers and possible methods for doing so.

Can whole brain nerve conduction velocity be derived from surface-recorded visual evoked potentials?

Reed, Vernon, and Johnson [Reed, T. E., Vernon, P. A., & Johnson, A. M. (2004). Sex difference in brain nerve conduction velocity in normal humans. Neuropsychologia, 42, 1709-1714] reported that "nerve conduction velocity" (NCV) of visual transmission from retina to the primary visual area (V1) is significantly faster in males than females. The authors estimated the NCV by dividing head length (nasion-to-inion distance) by the latency of the well-known P100 component of the visual evoked potential (VEP). Here, we critically examine these metrics and we contend that knowledge of the underlying physiology of neural transmission across the initial stages of the visual processing hierarchy dictates that a number of their assumptions cannot be reasonably upheld. Alternative, and we believe, more parsimonious interpretations of the data are also proposed.