The relationship of prenatal and perinatal complications to cognitive functioning at age 7 in the New England Cohorts of the National Collaborative Perinatal Project

Children's cognitive performance and suicide risk through middle adulthood

BACKGROUND

Longitudinal studies show that lower cognitive performance in adolescence and early adulthood is associated with higher risk of suicide death throughout adulthood. However, it is unclear whether this cognitive vulnerability originates earlier in childhood since studies conducted in children are scarce and have inconsistent results.

METHODS

Vital status of 49,853 individuals born between 1959 and 1966 to participants in the Collaborative Perinatal Project cohort was determined by a probabilistic linkage to the National Death Index, covering all US deaths occurring from 1979 through 2016. Cox proportional hazard models were used to examine associations of general, verbal, and non-verbal intelligence at ages 4 and 7, and academic skills at age 7 with suicide death coded according to ICD-9/10 criteria, while accounting for sociodemographic and pregnancy factors previously associated with suicide in this sample.

RESULTS

By the end of 2016, 288 cohort members had died by suicide. Cognitive performance at 7 years on tests with verbal components was associated with suicide risk (average vs. high verbal intelligence, HR = 1.97, 95% CI 1.05-3.71; low vs. high spelling skills, HR = 2.02, 95% CI 1.16-3.51; low vs. high reading skills, HR = 2.01, 95% CI 1.27-3.17). Associations were still evident, especially for verbal intelligence and reading skills, but hazard ratios were attenuated after adjusting for prenatal and sociodemographic factors at birth (verbal intelligence, HR = 1.97, 95% CI 1.03-3.78; spelling, HR = 1.61, 95% CI 0.90-2.88; reading, HR = 1.67, 95% CI 1.02-2.72).

CONCLUSIONS

Childhood neurocognitive performance is associated with vulnerability to suicide mortality through middle-adulthood, suggesting that there might be a cognitive diathesis for suicide originating in early childhood. Future studies should examine how multiple domains of childhood cognitive performance contribute to vulnerability to suicide risk, including by increasing risk for social and environmental factors that are associated not only with suicide but also with many types of psychiatric disorders.

Environmental Risk Factors and Cognitive Outcomes in Psychosis: Pre-, Perinatal, and Early Life Adversity

Risk for psychosis begins to accumulate as early as the fetal period through exposure to obstetric complications like fetal hypoxia, maternal stress, and prenatal infection. Stressors in the postnatal period, such as childhood trauma, peer victimization, and neighborhood-level adversity, further increase susceptibility for psychosis. Cognitive difficulties are among the first symptoms to emerge in individuals who go on to develop a psychotic disorder. We review the relationship between pre-, perinatal, and early childhood adversities and cognitive outcomes in individuals with psychosis. Current evidence shows that the aforementioned environmental risk factors may be linked to lower overall intelligence and executive dysfunction, beginning in the premorbid period and persisting into adulthood in individuals with psychosis. It is likely that early life stress contributes to cognitive difficulties in psychosis through dysregulation of the body's response to stress, causing changes such as increased cortisol levels and chronic immune activation, which can negatively impact neurodevelopment. Intersectional aspects of identity (e.g., sex/gender, race/ethnicity), as well as gene-environment interactions, likely inform the developmental cascade to cognitive difficulties throughout the course of psychotic disorders and are reviewed below. Prospective studies of birth cohorts will serve to further clarify the relationship between early-life environmental risk factors and cognitive outcomes in the developmental course of psychotic disorders. Specific methodological recommendations are provided for future research.

Are there sex differences in fetal growth strategies and in the long-term effects of pregnancy complications on cognitive functioning?

Males and females have been proposed to have different prenatal growth strategies, whereby males invest more in fetal growth and less in placental development, leaving them more susceptible to early-life adversity. We tested predictions of this hypothesis using data from the National Collaborative Perinatal Project. Male newborns were heavier than females, but there was no difference in placental weight, adjusting for birthweight. Among infants born prior to 33 weeks, the difference in birthweight between males and females was greater among those who did not survive than among those who did, potentially reflecting a strategy whereby males maintained growth in the face of prenatal insults, while females adjusted growth. However, there was no significant difference in mortality between the sexes. Being born small-for-gestational age or very preterm (prior to 33 weeks) was associated with significantly reduced performance for most of the cognitive traits examined at 7 years, although maternal preeclampsia was associated with reduced performance in fewer traits. Generally, these effects of early-life adversity (poor fetal growth, prematurity, and preeclampsia) did not differ between the sexes. However, analyzing the sexes separately (rather than testing the interaction between sex and adversity) resulted in numerous spurious sex-specific effects, whereby the effect of early-life adversity appeared to be significant in one sex but not the other. Overall, we found little support for the hypothesis that males prioritize growth more than females, and that this makes them more susceptible to early-life adversity. Furthermore, our results show that analyzing the sexes separately, rather than testing the adversity by sex interaction, can be highly misleading.

Perspective: Gestational Tryptophan Fluctuation Altering Neuroembryogenesis and Psychosocial Development

Tryptophan, as the sole precursor of serotonin, mainly derived from diets, is essential for neurodevelopment and immunomodulation. Gestational tryptophan fluctuation may account for the maternal-fetal transmission in determining neuroembryogenesis with long-lasting effects on psychological development. Personality disorders and social exclusion are related to psychosocial problems, leading to impaired social functioning. However, it is not clear how the fluctuation in mother-child transmission regulates the neuroendocrine development and gut microbiota composition in progeny due to that tryptophan metabolism in pregnant women is affected by multiple factors, such as diets (tryptophan-enriched or -depleted diet), emotional mental states (anxiety, depression), health status (hypertension, diabetes), and social support as well as stresses and management skills. Recently, we have developed a non-mammal model to rationalize those discrepancies without maternal effects. This perspective article outlines the possibility and verified the hypothesis in bully-victim research with this novel model: (1). Summarizes the effects of the maternal tryptophan administration on the neuroendocrine and microbial development in their offspring; (2). Highlights the inconsistency and limitations in studying the relationship between gestational tryptophan exposure and psychosocial development in humans and viviparous animals; and (3). Evidences that embryonic exposure to tryptophan and its metabolite modify bullying interactions in the chicken model. With the current pioneer researches on the biomechanisms underlying the bully-victim interaction, the perspective article provides novel insights for developing appropriate intervention strategies to prevent psychological disorders among individuals, especially those who experienced prenatal stress, by controlling dietary tryptophan and medication therapy during pregnancy.

A single prenatal lipopolysaccharide injection has acute, but not long-lasting, effects on cerebral kynurenine pathway metabolism in mice

In rodents, a single injection of lipopolysaccharide (LPS) during gestation causes chemical and functional abnormalities in the offspring. These effects may involve changes in the kynurenine pathway (KP) of tryptophan degradation and may provide insights into the pathophysiology of psychiatric diseases. Using CD1 mice, we examined acute and long-term effects of prenatal LPS treatment on the levels of kynurenine and its neuroactive downstream products kynurenic acid (KYNA), 3-hydroxykynurenine (3-HK) and quinolinic acid. To this end, LPS (100 μg/kg, i.p.) was administered on gestational day 15, and KP metabolites were measured 4 and 24 h later or in adulthood. After 4 h, kynurenine, KYNA and 3-HK levels were elevated in the fetal brain, 3-HK and KYNA levels were increased in the maternal plasma, and kynurenine was increased in the maternal brain, whereas no changes were seen in the placenta. These effects were less prominent after 24 h, and prenatal LPS did not affect the basal levels of KP metabolites in the forebrain of adult animals. In addition, a second LPS injection (1 mg/kg) in adulthood in the offspring of prenatally saline- and LPS-treated mice caused a similar elevation in 3-HK levels in both groups after 24 h, but the effect was significantly more pronounced in male mice. Thus, acute immune activation during pregnancy has only short-lasting effects on KP metabolism and does not cause cerebral KP metabolites to be disproportionally affected by a second immune challenge in adulthood. However, prenatal KYNA elevations still contribute to functional abnormalities in the offspring.

Early childhood growth trajectory and later cognitive ability: evidence from a large prospective birth cohort of healthy term-born children

BACKGROUND

Most studies of associations between child growth and cognitive ability were based on size at one or two ages and a single measure of cognition. We aimed to characterize different aspects of early growth and their associations with cognitive outcomes in childhood through adolescence.

METHODS

In a sample of 12 368 Belarusian children born at term, we examined associations of length/height and weight trajectories over the first 6.5 years of life with cognitive ability at 6.5 and 16 years and its change over time. We estimated growth trajectories using two random-effects models-the SuperImposition by Translation and Rotation to model overall patterns of growth and the Jenss-Bayley to distinguish growth in infancy from post infancy. Cognitive ability was measured using the Wechsler Abbreviated Scales of Intelligence at 6.5 years and the computerized NeuroTrax test at 16 years.

RESULTS

Higher length/height between birth and 6.5 years was associated with higher cognitive scores at 6.5 and 16 years {2.7 points [95% confidence interval (CI): 2.1, 3.2] and 2.5 points [95% CI: 1.9, 3.0], respectively, per standard deviation [SD] increase}. A 1-SD delay in the childhood height-growth spurt was negatively associated with cognitive scores [-2.4 (95% CI: -3.0, -1.8) at age 6.5; -2.2 (95% CI: -2.7, -1.6) at 16 years]. Birth size and post-infancy growth velocity were positively associated with cognitive scores at both ages. Height trajectories were not associated with the change in cognitive score. Similar results were observed for weight trajectories.

CONCLUSIONS

Among term infants, the overall size, timing of the childhood growth spurt, size at birth and post-infancy growth velocity were all associated with cognitive ability at early-school age and adolescence.

A Unifying Theory for Autism: The Pathogenetic Triad as a Theoretical Framework

This paper presents a unifying theory for autism by applying the framework of a pathogenetic triad to the scientific literature. It proposes a deconstruction of autism into three contributing features (an autistic personality dimension, cognitive compensation, and neuropathological risk factors), and delineates how they interact to cause a maladaptive behavioral phenotype that may require a clinical diagnosis. The autistic personality represents a common core condition, which induces a set of behavioral issues when pronounced. These issues are compensated for by cognitive mechanisms, allowing the individual to remain adaptive and functional. Risk factors, both exogenous and endogenous ones, show pathophysiological convergence through their negative effects on neurodevelopment. This secondarily affects cognitive compensation, which disinhibits a maladaptive behavioral phenotype. The triad is operationalized and methods for quantification are presented. With respect to the breadth of findings in the literature that it can incorporate, it is the most comprehensive model yet for autism. Its main implications are that (1) it presents the broader autism phenotype as a non-pathological core personality domain, which is shared across the population and uncoupled from associated features such as low cognitive ability and immune dysfunction, (2) it proposes that common genetic variants underly the personality domain, and that rare variants act as risk factors through negative effects on neurodevelopment, (3) it outlines a common pathophysiological mechanism, through inhibition of neurodevelopment and cognitive dysfunction, by which a wide range of endogenous and exogenous risk factors lead to autism, and (4) it suggests that contributing risk factors, and findings of immune and autonomic dysfunction are clinically ascertained rather than part of the core autism construct.

Association Between the Duration of Untreated Psychosis and Selective Cognitive Performance in Community-Dwelling Individuals With Chronic Untreated Schizophrenia in Rural China

IMPORTANCE

Cognitive deficits constitute core features of schizophrenia, but the trajectories of cognitive difficulties in chronic untreated schizophrenia remain unclear.

OBJECTIVE

To assess the association of neuropsychological deficits with duration of untreated psychosis in individuals with chronic untreated schizophrenia.

DESIGN, SETTING, AND PARTICIPANTS

Community-dwelling individuals with chronic untreated schizophrenia (untreated patient group) and individuals without mental illness (control group) were recruited from predominantly rural communities in Ningxia, China between June 20, 2016, and August 6, 2019, and administered the Structured Clinical Interview for DSM-IV, the Mini-Mental State Examination, an 8-test version of the MATRICS Consensus Cognition Battery adapted for use in individuals with low levels of education, and a measure of social cognition.

MAIN OUTCOMES AND MEASURES

Comparison of cognitive test scores between the two groups and association of cognitive test scores with duration of untreated schizophrenia.

RESULTS

The patient group included 197 individuals with chronic untreated schizophrenia (101 men [51.3%]; mean [SD] age, 52.1 [11.8] years; median [interquartile range] years of schooling, 3 [0-6] years; median [interquartile range] years of untreated psychosis, 22.9 [14.9-32.8] years). The control group included 220 individuals (118 men [53.6%]; mean [SD] age, 52.1 [11.2] years; median [interquartile range] years of schooling, 4 [0-6] years). The untreated patient group performed significantly worse than the control group on all cognitive measures (adjusted partial Spearman correlation coefficient [Spearman ρ] ranged from -0.35 for the revised Chinese version of the Reading the Mind in the Eyes Test to -0.60 for the Brief Visuospatial Memory Test-Revised; P < .001 for all comparisons). Longer durations of untreated psychosis were associated with lower performance in 3 MATRICS Consensus Cognition Battery measures assessing different aspects of executive functioning (Brief Visuospatial Memory Test-Revised [ρ = -0.20; P = .04]; Brief Assessment of Cognition in Schizophrenia, Symbol Coding subtest [ρ = -0.35; P < .001]; and Neuropsychological Assessment Battery, Mazes subtest [ρ = -0.24; P = .01]). The median duration of untreated psychosis (22.9 years) was associated with estimated score reductions in the 3 measures of 34% (95% CI, 10%-52%), 43% (95% CI, 28%-55%), and 57% (95% CI, 31%-73%), respectively.

CONCLUSIONS AND RELEVANCE

The findings of this study suggest that long-term untreated schizophrenia was associated with decreases in selective cognitive abilities; both neurodegenerative pathology and neurodevelopmental dysfunction may be factors in cognition in persistent psychosis. Expanding research to include cohorts of patients from underserved rural communities in low- and middle-income countries may provide new insights about the etiological factors, disease course, and management of schizophrenia.

Prenatal and perinatal risk and protective factors for psychosis: a systematic review and meta-analysis

BACKGROUND

Prenatal and perinatal insults are implicated in the aetiopathogenesis of psychotic disorders but the consistency and magnitude of their associations with psychosis have not been updated for nearly two decades. The aim of this systematic review and meta-analysis was to provide a comprehensive and up-to-date synthesis of the evidence on the association between prenatal or perinatal risk and protective factors and psychotic disorders.

METHODS

In this systematic review and meta-analysis, we searched the Web of Science database for articles published up to July 20, 2019. We identified cohort and case-control studies examining the association (odds ratio [OR]) between prenatal and perinatal factors and any International Classification of Diseases (ICD) or Diagnostic and Statistical Manual of Mental Disorders (DSM) non-organic psychotic disorder with a healthy comparison group. Other inclusion criteria were enough data available to do the analyses, and non-overlapping datasets. We excluded reviews, meta-analyses, abstracts or conference proceedings, and articles with overlapping datasets. Data were extracted according to EQUATOR and PRISMA guidelines. Extracted variables included first author, publication year, study type, sample size, type of psychotic diagnosis (non-affective psychoses or schizophrenia-spectrum disorders, affective psychoses) and diagnostic instrument (DSM or ICD and version), the risk or protective factor, and measure of association (primary outcome). We did random-effects pairwise meta-analyses, Q statistics, I² index, sensitivity analyses, meta-regressions, and assessed study quality and publication bias. The study protocol was registered at PROSPERO, CRD42017079261.

FINDINGS

152 studies relating to 98 risk or protective factors were eligible for analysis. Significant risk factors were: maternal age younger than 20 years (OR 1·17) and 30-34 years (OR 1·05); paternal age younger than 20 years (OR 1·31) and older than 35 years (OR 1·28); any maternal (OR 4·60) or paternal (OR 2·73) psychopathology; maternal psychosis (OR 7·61) and affective disorder (OR 2·26); three or more pregnancies (OR 1·30); herpes simplex 2 (OR 1·35); maternal infections not otherwise specified (NOS; OR 1·27); suboptimal number of antenatal visits (OR 1·83); winter (OR 1·05) and winter to spring (OR 1·05) season of birth in the northern hemisphere; maternal stress NOS (OR 2·40); famine (OR 1·61); any famine or nutritional deficits in pregnancy (OR 1·40); maternal hypertension (OR 1·40); hypoxia (OR 1·63); ruptured (OR 1·86) and premature rupture (OR 2·29) of membranes; polyhydramnios (OR 3·05); definite obstetric complications NOS (OR 1·83); birthweights of less than 2000 g (OR 1·84), less than 2500 g (OR 1·53), or 2500-2999 g (OR 1·23); birth length less than 49 cm (OR 1·17); small for gestational age (OR 1·40); premature birth (OR 1·35), and congenital malformations (OR 2·35). Significant protective factors were maternal ages 20-24 years (OR 0·93) and 25-29 years (OR 0·92), nulliparity (OR 0·91), and birthweights 3500-3999 g (OR 0·90) or more than 4000 g (OR 0·86). The results were corrected for publication biases; sensitivity and meta-regression analyses confirmed the robustness of these findings for most factors.

INTERPRETATION

Several prenatal and perinatal factors are associated with the later onset of psychosis. The updated knowledge emerging from this study could refine understanding of psychosis pathogenesis, enhance multivariable risk prediction, and inform preventive strategies.

FUNDING

None.

Effects of prenatal bacterial infection on cognitive performance in early childhood

BACKGROUND

Previous epidemiologic studies have reported adverse neurodevelopmental sequelae following prenatal infectious exposure, yet long-term effects estimated from these observational studies are often subject to biases due to confounding and loss to follow-up.

OBJECTIVES

We demonstrate the joint use of inverse probability (IP) treatment and censoring weights when evaluating neurotoxic effects of prenatal bacterial infection.

METHODS

We applied IP weighting for both treatment and censoring to estimate the effects of maternal bacterial infection during pregnancy on mean intelligence quotient (IQ) scores measured at age 7 using the Wechsler Intelligence Scale for Children. Participants were members of a population-based pregnancy cohort recruited in the Boston and Providence sites of the Collaborative Perinatal Project between 1959 and 1966 (n = 11 984). We calculated average treatment effects (ATE) and average treatment effects on the treated (ATT) using IP weights estimated via generalized boosted models.

RESULTS

ATE- and ATT-weighted mean IQ scores were lowest among offspring exposed to multi-systemic bacterial infection during pregnancy and highest for those unexposed. The effects of prenatal bacterial infection were greater among male offspring, particularly on performance IQ scores. Offspring who were exposed to multi-systemic bacterial infection in the third trimester displayed the largest reduction in mean full-scale, verbal, and performance IQ scores at age 7 compared to those unexposed or exposed in earlier trimesters.

CONCLUSIONS

We find that prenatal bacterial infection is associated with cognitive impairments at age 7. Associations are strongest for more severe infections, that occur in the third trimester, and among males. Public health intervention targeting bacterial infection in pregnant women may help enhance the cognitive development of offspring.

Maternal Bacterial Infection During Pregnancy and Offspring Risk of Psychotic Disorders: Variation by Severity of Infection and Offspring Sex

OBJECTIVE

Previous studies suggest that prenatal immune challenges may elevate the risk of schizophrenia and related psychoses in offspring, yet there has been limited research focused on maternal bacterial infection. The authors hypothesized that maternal bacterial infection during pregnancy increases offspring risk of psychotic disorders in adulthood, and that the magnitude of this association varies as a function of severity of infectious exposure and offspring sex.

METHODS

The authors analyzed prospectively collected data from 15,421 pregnancies among women enrolled between 1959 and 1966 at two study sites through the Collaborative Perinatal Project. The sample included 116 offspring with confirmed psychotic disorders. The authors estimated associations between maternal bacterial infection during pregnancy and psychosis risk over the subsequent 40 years, stratified by offspring sex and presence of reported parental mental illness, with adjustment for covariates.

RESULTS

Maternal bacterial infection during pregnancy was strongly associated with psychosis in offspring (adjusted odds ratio=1.8, 95% CI=1.2-2.7) and varied by severity of infection and offspring sex. The effect of multisystemic bacterial infection (adjusted odds ratio=2.9, 95% CI=1.3-5.9) was nearly twice that of less severe localized bacterial infection (adjusted odds ratio=1.6, 95% CI=1.1-2.3). Males were significantly more likely than females to develop psychosis after maternal exposure to any bacterial infection during pregnancy.

CONCLUSIONS

The study findings suggest that maternal bacterial infection during pregnancy is associated with an elevated risk for psychotic disorders in offspring and that the association varies by infection severity and offspring sex. These findings call for additional investigation and, if the findings are replicated, public health and clinical efforts that focus on preventing and managing bacterial infection in pregnant women.

Prenatal Risk Predicts Preschooler Executive Function: A Cascade Model

Little research has considered whether prenatal experience contributes to executive function (EF) development above and beyond postnatal experience. This study tests direct, mediated, and moderated associations between prenatal risk factors and preschool EF and IQ in a longitudinal sample of 1,292 children from the Family Life Project. A composite of prenatal risk factors (i.e., low birth weight, prematurity, maternal emotional problems, maternal prepregnancy obesity, and obstetric complications) significantly predicted EF and IQ at age 3, above quality of the postnatal environment. This relationship was indirect, mediated through infant general cognitive abilities. Quality of the postnatal home and child-care environments did not moderate the cascade model. These findings highlight the role of prenatal experience as a contributor to individual differences in cognitive development.

Maternal genotype determines kynurenic acid levels in the fetal brain: Implications for the pathophysiology of schizophrenia

BACKGROUND

Several studies suggest a pathophysiologically relevant association between increased brain levels of the neuroinhibitory tryptophan metabolite kynurenic acid and cognitive dysfunctions in people with schizophrenia. Elevated kynurenic acid in schizophrenia may be secondary to a genetic alteration of kynurenine 3-monooxygenase, a pivotal enzyme in the kynurenine pathway of tryptophan degradation. In rats, prenatal exposure to kynurenine, the direct bioprecursor of kynurenic acid, induces cognitive impairments reminiscent of schizophrenia in adulthood, suggesting a developmental dimension to the link between kynurenic acid and schizophrenia.

AIM

The purpose of this study was to explore the possible impact of the maternal genotype on kynurenine pathway metabolism.

METHODS

We exposed pregnant wild-type ( Kmo^+/+ ) and heterozygous ( Kmo^+/-) mice to kynurenine (10 mg/day) during the last week of gestation and determined the levels of kynurenic acid and two other neuroactive kynurenine pathway metabolites, 3-hydroxykynurenine and quinolinic acid, in fetal brain and placenta on embryonic day 17/18.

RESULTS

Maternal kynurenine treatment raised kynurenic acid levels significantly more in the brain of heterozygous offspring of Kmo^+/- than in the brain of Kmo^+/+ offspring. Conversely, 3-hydroxykynurenine and quinolinic acid levels in the fetal brain tended to be lower in heterozygous animals derived from kynurenine-treated Kmo^+/- mice than in corresponding Kmo^+/+ offspring. Genotype-related effects on the placenta were qualitatively similar but less pronounced. Kynurenine treatment also caused a preferential elevation in cerebral kynurenic acid levels in Kmo^+/- compared to Kmo^+/+ dams.

CONCLUSIONS

The disproportionate kynurenic acid increase in the brain of Kmo^+/- animals indicates that the maternal Kmo genotype may play a key role in the pathophysiology of schizophrenia.

Intrauterine growth restriction and development of the hippocampus: implications for learning and memory in children and adolescents

Intrauterine growth restriction (IUGR) is often the result of compromised placental function and suboptimal uteroplacental blood flow. Children born with IUGR have impaired cognitive functioning and specific memory deficits, indicating long-lasting impairments in hippocampal functioning; indeed, hippocampal volume is reduced in infants with IUGR. Animal studies have provided valuable insight into the nature of deficits in hippocampal-dependent functions observed in children born with IUGR; outcomes of experimental IUGR reveal reduced neuron numbers and morphological alterations in the cornu ammonis fields 1 and 3 and dentate gyrus subregions of the hippocampus. However, whether such early and ongoing structural changes in the hippocampus could account for deficits in spatial memory reported in adolescent rats with IUGR is yet to be established. Understanding the association between hippocampal structural and functional alterations in IUGR will aid in the development of interventions to minimise the effect of IUGR on the hippocampus and long-term cognitive outcomes.

Cognitive development prior to onset of psychosis

Schizophrenia patients commonly exhibit substantial and diffuse cognitive impairment. Evidence suggests that subtle cognitive deficits are already apparent in childhood and adolescence, many years prior to onset of psychosis. While there is almost unequivocal evidence of some degree of cognitive impairment in individuals who later develop schizophrenia, the literature remains inconclusive regarding the exact nature of this impairment and warrants careful review and interpretation. Meta-analytic findings suggest that individuals who later develop schizophrenia, but not related disorders, such as bipolar disorder, exhibit a premorbid IQ deficit of around 8 points. Several studies have also found evidence for premorbid deficits across most cognitive domains, such as language, processing speed and executive functions. Longitudinal studies, although rare, suggest that individuals who go on to develop schizophrenia may show a course of increasing cognitive impairment prior to onset of psychosis. While evidence regarding the etiology of premorbid deficits is scarce, common and rare genetic variants, as well as environmental factors such as obstetric complications and cannabis use may play an important role and warrant further examination. In this selected review, we give an overview of population-based studies on premorbid cognitive deficits in schizophrenia, with a special focus on evidence regarding the specificity, profile and course of these deficits.

[Socio-cognitive development in early childhood: the challenges to reach in public health at the area of Sabana Centro and Boyacá]

OBJECTIVE

The need to build public health systems that ensure comprehensive child development enables a characterization of the factors that favor or restrict the integral development of children under the age of six. That is in order to identify them as necessary components to be taken into account in public policies.

METHOD

A survey was carried out with 1 177 mothers or family caregivers of children under six years old in 16 municipalities of Cundinamarca and Boyacá, and the respective socio-cognitive development of their own sons and daughters was measured with the Haizea-Llevant table and also tasks related to the use of core knowledge systems.

RESULTS

Through bivariate and multivariate statistical analyzes, it was found that the factors that are significant to address a public health proposal that seeks the integral development of children under six years of age are: socio-economic conditions of households, complications in childbirth, the starting age of solid foods, mothers' working shifts, rules on daily routines and play practices such as reading, painting and sport activities.

CONCLUSIONS

A health system that acknowledges the results presented should offer specialized care that seeks welfare in childhood and early childhood, which can only be achieved if health policies begin to consider domestic and daily factors that cannot be excluded from public policies and it should guarantee different levels of intervention of social and particular impact.

Socioeconomic disadvantage and neural development from infancy through early childhood

BACKGROUND

Early social experiences are believed to shape neurodevelopment, with potentially lifelong consequences. Yet minimal evidence exists regarding the role of the social environment on children's neural functioning, a core domain of neurodevelopment.

METHODS

We analysed data from 36 443 participants in the United States Collaborative Perinatal Project, a socioeconomically diverse pregnancy cohort conducted between 1959 and 1974. Study outcomes included: physician (neurologist or paediatrician)-rated neurological abnormality neonatally and thereafter at 4 months and 1 and 7 years; indicators of neurological hard signs and soft signs; and indicators of autonomic nervous system function.

RESULTS

Children born to socioeconomically disadvantaged parents were more likely to exhibit neurological abnormalities at 4 months [odds ratio (OR) = 1.20; 95% confidence interval (CI) = 1.06, 1.37], 1 year (OR = 1.35; CI = 1.17, 1.56), and 7 years (OR = 1.67; CI = 1.48, 1.89), and more likely to exhibit neurological hard signs (OR = 1.39; CI = 1.10, 1.76), soft signs (OR = 1.26; CI = 1.09, 1.45) and autonomic nervous system dysfunctions at 7 years. Pregnancy and delivery complications, themselves associated with socioeconomic disadvantage, did not account for the higher risks of neurological abnormalities among disadvantaged children.

CONCLUSIONS

Parental socioeconomic disadvantage was, independently from pregnancy and delivery complications, associated with abnormal child neural development during the first 7 years of life. These findings reinforce the importance of the early environment for neurodevelopment generally, and expand knowledge regarding the domains of neurodevelopment affected by environmental conditions. Further work is needed to determine the mechanisms linking socioeconomic disadvantage with children's neural functioning, the timing of such mechanisms and their potential reversibility.

Independent and combined influence of neonatal and current body composition on academic performance in youth: The UP & DOWN Study

BACKGROUNDS

Unhealthy body composition is a cause for concern across the lifespan.

OBJECTIVE

The objective of this study was to examine the independent and combined associations between neonatal and current body composition with academic performance among youth.

METHODS

This cross-sectional study was conducted with a total of 1557 youth (745 girls) aged 10.4 ± 3.4 years. Birth weight and length at birth were self-reported. Current body composition was assessed by body mass index (BMI), waist circumference (WC) and percentage of body fat (BF%). Academic performance was assessed through schools records.

RESULTS

Birth weight was related to all academic variables in boys, independent of potential confounders, including BMI; whereas WC, BMI and BF% were related to all academic performance indicators in both boys and girls, independent of potential confounders, including birth weight (all P < 0.05). In addition, the combined adverse effects of low birth weight and current overweight on academic performance were observed in both boys and girls for grade point average (GPA) indicator. Boys in the group with none adverse effect had significantly higher scores in GPA (score +0.535; 95% confidence interval, 0.082-0.989) than boys in the group of both adverse effects (P < 0.007); among girls, GPA score was higher in the group with none adverse effect than in the groups with one or two adverse effects (P for trend = 0.029).

CONCLUSIONS

Neonatal and current body composition, both independently and combined, may influence academic performance in youth.

Perinatal oxytocin increases the risk of offspring bipolar disorder and childhood cognitive impairment

BACKGROUND

We tested the hypothesis that perinatal oxytocin, given to pregnant women to induce labor, is related to offspring bipolar disorder (BP) and worse childhood cognitive performance among offspring. We also tested the association between childhood cognition and later BP.

METHODS

A population-based birth cohort derived from the Child Health and Development Study (CHDS) which included nearly all pregnant women receiving obstetric care from the Kaiser Permanente Medical Care Plan, Northern California Region (KPNC) between 1959 and 1966. Prospectively obtained medical and offspring cognitive performance were used. Potential cases with BP from the cohort were identified by database linkages. This protocol identified 94 cases who were matched 1:8 to controls.

RESULTS

Perinatal oxytocin was associated with a 2.4 times increased odds of later BP. Oxytocin was also associated with decreased performance on the Raven Matrices, but not on the Peabody Picture Vocabulary Test (PPVT). Childhood cognition was not associated with later BP.

LIMITATIONS

Loss to follow-up must be considered in all birth cohort studies. In addition, the childhood cognitive battery did not include tests related to multiple domains of cognition which have been associated with later BP. A third limitation is the modest sample size of those exposed to oxytocin.

CONCLUSIONS

This study provides evidence for a potentially important perinatal risk factor for BP and cognitive impairment in childhood. While the association between perinatal oxytocin and offspring BP must be viewed cautiously until further studies can attempt to replicate the result, it lends support to the broader view that neurodevelopmental factors contribute to BP.

Impairment of executive function in Kenyan children exposed to severe falciparum malaria with neurological involvement

BACKGROUND

Persistent neurocognitive impairments occur in a fifth of children hospitalized with severe falciparum malaria. There is little data on the association between different neurological phenotypes of severe malaria (seizures, impaired consciousness and prostration) and impairments in executive function.

METHODS

Executive functioning of children exposed to severe malaria with different neurological phenotypes (N = 58) and in those unexposed (N = 56) was examined using neuropsychological tests such as vigilance test, test for everyday attention test for children (TEA-Ch), contingency naming test (CNT) and self-ordered pointing test (SOPT). Linear regression was used to determine the association between neurological phenotypes of severe malaria and executive function performance scores, accounting for potential confounders.

RESULTS

Children with complex seizures in severe malaria performed more poorly than unexposed controls in the vigilance (median efficiency scores (interquartile range) = 4.84 (1.28-5.68) vs. 5.84 (4.71-6.42), P = 0.030) and SOPT (mean errors (standard deviation) = 29.50 (8.82) vs. 24.80 (6.50), P = 0.029) tests, but no differences were observed in TEA-Ch and CNT tests. Performance scores for other neurological phenotypes of severe malaria were similar with those of unexposed controls. After accounting for potential confounders, such as child's age, sex, schooling; maternal age, schooling and economic activity; perinatal factors and history of seizures, complex seizures remained associated with efficiency scores in the vigilance test (beta coefficient (β) (95% confidence interval (CI)) = -0.40 (-0.67, -0.13), P = 0.006) and everyday attention scores of the TEA-Ch test (β (95% CI) = -0.57 (-1.04, -0.10), P = 0.019); the association with SOPT error scores was weak (β (95% CI) = 4.57 (-0.73-9.89), P = 0.089). Combined neurological phenotypes were not significantly associated with executive function performance scores.

CONCLUSION

Executive function impairment in children with severe malaria is associated with specific neurological phenotypes, particularly complex seizures. Effective prophylaxis and management of malaria-associated acute seizures may improve executive functioning performance scores of children.

Birth weight and neurocognition in schizophrenia spectrum disorders

Low birth weight is associated with both schizophrenia and neurocognitive impairment. Yet, to our knowledge, no previous study has examined the relationship between lower birth weight and neurocognitive deficits in schizophrenia spectrum disorders (SSD). In this preliminary study, we investigated the relationship using a broad neuropsychological battery in cases with SSD and matched control subjects. The sample consisted of all subjects in the Developmental Insult and Brain Anomaly in Schizophrenia study, a nested case-control investigation developed from a large birth cohort, which followed subjects longitudinally. Case ascertainment was based on computerized record linkages between the birth cohort members and the Kaiser Permanente Medical Care Plan, and all diagnoses were confirmed by consensus diagnosis following the Diagnostic Interview for Genetic Studies. Lower birth weight was associated with impairment in executive function, working memory, generalized intellectual function, and neuromotor function in cases with SSD but not in control subjects. No deficits were observed in verbal memory for either group. These results support the hypothesis that lower birth weight plays a role in neuropsychological disruptions in SSD and that the antecedents of lower birth weight may have a greater impact on these disruptions in SSD than in controls. These data may facilitate a better understanding of the etiopathogenesis of the cognitive underpinnings of SSD.

Neuropsychological performance and family history in children at age 7 who develop adult schizophrenia or bipolar psychosis in the New England Family Studies

BACKGROUND

Persons developing schizophrenia (SCZ) manifest various pre-morbid neuropsychological deficits, studied most often by measures of IQ. Far less is known about pre-morbid neuropsychological functioning in individuals who later develop bipolar psychoses (BP). We evaluated the specificity and impact of family history (FH) of psychosis on pre-morbid neuropsychological functioning.

METHOD

We conducted a nested case-control study investigating the associations of neuropsychological data collected systematically at age 7 years for 99 adults with psychotic diagnoses (including 45 SCZ and 35 BP) and 101 controls, drawn from the New England cohort of the Collaborative Perinatal Project (CPP). A mixed-model approach evaluated full-scale IQ, four neuropsychological factors derived from principal components analysis (PCA), and the profile of 10 intelligence and achievement tests, controlling for maternal education, race and intra-familial correlation. We used a deviant responder approach (<10th percentile) to calculate rates of impairment.

RESULTS

There was a significant linear trend, with the SCZ group performing worst. The profile of childhood deficits for persons with SCZ did not differ significantly from BP. Neuropsychological impairment was identified in 42.2% of SCZ, 22.9% of BP and 7% of controls. The presence of psychosis in first-degree relatives (FH+) significantly increased the severity of childhood impairment for SCZ but not for BP.

CONCLUSIONS

Pre-morbid neuropsychological deficits are found in a substantial proportion of children who later develop SCZ, especially in the SCZ FH+ subgroup, but less so in BP, suggesting especially impaired neurodevelopment underlying cognition in pre-SCZ children. Future work should assess genetic and environmental factors that explain this FH effect.

Impact of fetal versus perinatal hypoxia on sex differences in childhood outcomes: developmental timing matters

PURPOSE

To examine how the timing of hypoxic exposure results in specific childhood outcomes and whether there is a differential effect by sex.

METHODS

A sample of 10,879 prospectively followed pregnancies was drawn from the Boston and Providence sites (New England, NE) of the National Collaborative Perinatal Project. Based on placental pathology, we developed and validated a measure of probable chronic placental hypoxia (CHP) and contrasted the effects of acute perinatal hypoxia on age 7 emotional, behavioral, and cognitive outcomes.

RESULTS

Perinatal hypoxia had a significant impact on multiple behavioral and cognitive outcomes in boys and girls by age 7, in contrast to probable CHP which had a differential effect on girls and boys such that there was decreased verbal IQ and increased inhibition in females alone.

CONCLUSIONS

Findings underscore the importance of considering the timing of obstetric complications and offspring sex in investigations of the impact of fetal and perinatal hypoxia on offspring's outcomes throughout the life course.

Synaptic dysfunction and intellectual disability

Intellectual disability (ID) is a common and highly heterogeneous paediatric disorder with a very severe social impact. Intellectual disability can be caused by environmental and/or genetic factors. Although in the last two decades a number of genes have been discovered whose mutations cause mental retardation, we are still far from identifying the impact of these mutations on brain functions. Many of the genes mutated in ID code for several proteins with a variety of functions: chromatin remodelling, pre-/post-synaptic activity, and intracellular trafficking. The prevailing hypothesis suggests that the ID phenotype could emerge from abnormal cellular processing leading to pre- and/or post-synaptic dysfunction. In this chapter, we focus on the role of small GTPases and adhesion molecules, and we discuss the mechanisms through which they lead to synaptic network dysfunction.

The Early Determinants of Adult Health Study

This issue of the Journal features collaborative follow-up studies of two unique pregnancy cohorts recruited during 1959-1966 in the United States. Here we introduce the Early Determinants of Adult Health (EDAH) study. EDAH was designed to compare health outcomes in midlife (age 40s) for same-sex siblings discordant on birthweight for gestational age. A sufficient sample of discordant siblings could only be obtained by combining these two cohorts in a single follow-up study. All of the subsequent six papers are either based upon the EDAH sample or are related to it in various ways. For example, three papers report results from studies that significantly extended the 'core' EDAH sample to address specific questions. We first present the overall design of and rationale for the EDAH study. Then we offer a synopsis of past work with the two cohorts to provide a context for both EDAH and the related studies. Next, we describe the recruitment and assessment procedures for the core EDAH sample. This includes the process of sampling and recruitment of potential participants; a comparison of those who were assessed and not assessed based on archived data; the methods used in the adult follow-up assessment; and the characteristics at follow-up of those who were assessed. We provide online supplementary tables with much further detail. Finally, we note further work in progress on EDAH and related studies, and draw attention to the broader implications of this endeavor.

Early life nutrition and metabolic programming

Research investigating the early programming of adult metabolic disease has in recent years provided much mechanistic insight into how the early environment impacts on long-term health. It includes studies addressing the roles of intrauterine nutrient availability, which is determined by maternal nutrition, maternal exposure to oxygen, toxic events, and infection; the placental interface; and also the early postnatal environment. This review will explore the epidemiological evidence for programming of metabolic disease and provide an overview of the various studies using animals to model metabolic phenotypic outcome. It will also discuss evidence for the proposed molecular mechanisms and the potential for intervention.

Children of parents with affective and nonaffective psychoses: a longitudinal study of behavior problems

OBJECTIVE

It is generally accepted that children of parents with schizophrenia or other forms of psychosis are at heightened risk for a range of behavioral problems. However, it remains unclear whether offspring of parents with different forms of psychosis (e.g., schizophrenia, other nonaffective psychoses, and affective psychoses) have distinct forms of behavioral problems (i.e., internalizing and externalizing).

METHOD

Behavioral observations of children of parents with psychosis (N=281) and parents without psychosis (N=185) were conducted at ages 4 and 7 years.

RESULTS

There were no significant differences between groups in behavior observed at age 4 years. At age 7 years, compared with children of unaffected parents, children of parents with psychosis had an adjusted odds ratio of 2.8 (95% CI=1.5-5.6) for externalizing problems, in particular for children of parents with schizophrenia (adjusted odds ratio=4.4; 95% CI=1.7-12.5). This increase in risk for externalizing problems was observed for female children only (adjusted odds ratio=8.1; 95% CI=2.5-26.3). In contrast, male children were at increased risk for internalizing problems (adjusted odds ratio=3.6; 95% CI=1.6-8.3).

CONCLUSIONS

Children of parents with various forms of psychosis are at risk for internalizing and externalizing problems by age 7 years. This risk varies by gender of the offspring. Implications for treatment of parents with psychotic disorders and high-risk children are discussed.

Genetics of early onset cognitive impairment

Intellectual disability (ID) is the leading socio-economic problem of health care, but compared to autism and schizophrenia, it has received very little public attention. Important risk factors for ID are malnutrition, cultural deprivation, poor health care, and parental consanguinity. In the Western world, fetal alcohol exposure is the most common preventable cause. Most severe forms of ID have genetic causes. Cytogenetically detectable and submicroscopic chromosomal rearrangements account for approximately 25% of all cases. X-linked gene defects are responsible in 10-12% of males with ID; to date, 91 of these defects have been identified. In contrast, autosomal gene defects have been largely disregarded, but due to coordinated efforts and the advent of next-generation DNA sequencing, this is about to change. As shown for Fra(X) syndrome, this renewed focus on autosomal gene defects will pave the way for molecular diagnosis and prevention, shed more light on the pathogenesis of ID, and reveal new opportunities for therapy.

Maternal age and paternal age are associated with distinct childhood behavioural outcomes in a general population birth cohort

BACKGROUND

Recent studies show that advanced paternal age (APA) is associated with an increased risk of neurodevelopmental disorders such as autism, bipolar disorder and schizophrenia. A body of evidence also suggests that individuals who develop schizophrenia show subtle deviations in a range of behavioural domains during their childhood. The aim of the study was to examine the relationship between paternal and maternal ages and selected behavioural measures in children using a large birth cohort.

METHOD

Participants were singleton children (n=21,753) drawn from the US Collaborative Perinatal Project. The outcome measures were assessed at 7 years. The main analyses examined the relationship between parental age and behavioural measures when adjusted for a range of potentially confounding variables, including age of the other parent, maternal race, socio-economic measures, sex, gestation length, maternal marital status, parental mental illness, and child's age-at-testing.

RESULTS

Advanced paternal age was associated with a significantly increased risk of adverse 'externalizing' behaviours at age seven years. For every five year increase in paternal age, the odds of higher 'externalizing' behaviours was increased by 12% (OR=1.12; 95% CI=1.03, 1.21, p<0.0001). The relationship persisted after adjusting for potential confounding factors. 'Internalizing' behavioural outcome was not associated with advanced paternal age. In contrast, advanced maternal age was significantly protective against adverse 'externalizing' behavioural outcomes, but associated with an increased risk of adverse 'internalizing' behavioural outcomes.

DISCUSSION

The offspring of older fathers show a distinctly different pattern of behaviours compared to the offspring of older mothers. The diverse socio-cultural and biologically-mediated factors that underpin these findings remain to be clarified. In light of secular trends related to delayed parenthood, the mechanisms underlying these findings warrant closer scrutiny.

Non-linear and gender-specific relationships among placental growth measures and the fetoplacental weight ratio

GOALS

Fetal growth depends on placental growth; the fetoplacental weight ratio (FPR) is a common proxy for the balance between fetal and placental growth. Male and female infants are known to have differing vulnerabilities in fetal life, during parturition and in infancy. We hypothesized that these differences may be paralleled by differences in how birth weight (BW) and the fetoplacental weight ratio (FPR) are affected by changes in placental proportions.

MATERIALS AND METHODS

Placental proportion measures (disk shape, larger and smaller chorionic diameters, chorionic plate area calculated as the area of an ellipse with the 2 given diameters, disk thickness, cord eccentricity and cord length) were available for 24,601 participants in the Collaborative Perinatal Project delivered between >34 and <43 completed weeks. The variables were standardized and entered into multiple automated regression splines (MARS 2.0, Salford Systems, Vista CA) to identify nonlinearities in the relationships of placental growth measures to BW and FPR with results compared for male and female infants.

RESULTS

Changes in chorionic plate growth in female compared to male infants resulted in a greater change in BW and FPR. The positive effects of umbilical cord length on BW reversed at the mean umbilical cord length in females and at +0.08 SD in male infants.

CONCLUSIONS

Female infants' BW and FPR are each more responsive to changes in placental chorionic plate growth dimensions than males; this may account for greater female resilience (and greater male vulnerability) to gestational stressors. The effect of umbilical cord length on FPR may be due to longer cords carrying greater fetal vascular resistance. Again male fetuses show a higher "threshold" to the negative effects of longer cords on FPR.

The antecedents of schizophrenia: a review of birth cohort studies

BACKGROUND

Birth cohort (BC) studies demonstrate that individuals who develop schizophrenia differ from the general population on a range of developmental indices. The aims of this article were to summarize key findings from BC studies in order to identify areas of convergence and to outline areas requiring further research.

METHOD

We define BC studies as studies based on general population BCs where data are collected prospectively from birth or childhood and which identify schizophrenia or related disorders as an outcome. To identify such studies, we searched various electronic databases using the search parameters (schizo* OR psych*) AND (birth cohort). We also checked the references of relevant articles and previous reviews.

RESULTS

We identified 11 BCs from 7 countries that have examined schizophrenia as an outcome in adulthood. There is relatively consistent evidence that, as a group, children who later develop schizophrenia have behavioral disturbances and psychopathology, intellectual and language deficits, and early motor delays. Evidence with respect to alterations in language, educational performance, and physical growth has also been identified in some studies. BC studies have also contributed evidence about a wide range of putative risk factors for schizophrenia.

CONCLUSIONS

BC studies have provided important, convergent insights into how the developmental trajectory of individuals who develop schizophrenia differs from their peers. The combination of new paradigms and larger cohorts, with the tools of modern epidemiology and biomedical science, is advancing our understanding of the developmental pathways to schizophrenia.

The Association of Birth Complications and Externalizing Behavior in Early Adolescents: Direct and Mediating Effects

Prior studies have shown that birth complications interact with psychosocial risk factors in predisposing to increased externalizing behavior in childhood and criminal behavior in adulthood. However, little is known about the direct relationship between birth complications and externalizing behavior. Furthermore, the mechanism by which the birth complications predispose to externalizing behavior is not well explored. This study aims to assess whether birth complications predispose to early adolescent externalizing behavior and to test whether Intelligence Quotient (IQ) mediates relationships between predictor and outcome variables. We used data from a prospective, longitudinal birth cohort of 1,795 3-year-old boys and girls from Mauritius to test hypotheses. Birth complications were assessed from hospital record data, malnutrition from a pediatric exam at age 3 years, psychosocial adversity from parental interviews at age 3 years, and externalizing behavior problems from parental ratings at age 11 years. We found that babies with birth complications are more likely to develop externalizing behavior problems at age 11. Low IQ was associated with birth complications and was found to mediate the link between early predictors and later externalizing behavior. These prospective, longitudinal findings have potential clinical implications for the identification of early adolescent externalizing behavior and for public health attempts to prevent the occurrence of child externalizing behavior problems.

How health status affects progress and performance in school: a population-based study

OBJECTIVE

To assess the effects of health status at birth and health status in the preschool years on educational outcomes to age 9 in a population-based birth cohort.

METHODS

Administrative data were used to follow all children born to Winnipeg mothers in 1990, and remaining in Manitoba until September 2004 (N = 5,873). A structural equation model was used, incorporating latent variables to represent Health Status at Birth, Major Illness and Minor Illness during the preschool years. The model also included the child's sex and exact age, along with a number of social, economic, and demographic characteristics of the child's family. The outcome was a combination of marks on Grade 3 Standards Tests and enrollment in the appropriate grade for age.

RESULTS

Major Illness in the preschool years had a significant influence on progress and performance in school (p = 0.0003), predicting 1.26% of the variation in the outcome. Minor Illness was weaker but still significant (p < 0.01). Health Status at Birth was not directly related to the outcome; its effect was mediated by Major and Minor Illness in childhood. Overall, the strongest predictors were the child's age and the area-level income, followed by the mother's age, family receipt of income assistance, the sex of the child, breastfeeding initiation (all p < 0.0001), and Major Illness.

CONCLUSIONS

Health status plays a statistically significant but substantively small role in explaining progress and performance in school among a population-based cohort. Major Illness was more important than Minor Illness, and these two factors completely mediated the influence of Health Status at Birth on the outcome. The strength of the social, economic, and demographic variables underscores the importance of the broader factors that affect both health and educational outcomes.

Maternal iron deficiency and the risk of schizophrenia in offspring

CONTEXT

Iron is essential for brain development and functioning. Emerging evidence suggests that iron deficiency in early life leads to long-lasting neural and behavioral deficits in infants and children. Adopting a life course perspective, we examined the effects of early iron deficiency on the risk of schizophrenia in adulthood.

OBJECTIVE

To determine whether maternal iron deficiency, assessed by maternal hemoglobin concentration during pregnancy, increases the susceptibility to schizophrenia spectrum disorders (SSDs) among offspring.

DESIGN

Data were drawn from a population-based cohort born from 1959 through 1967 and followed up for development of SSD from 1981 through 1997.

PARTICIPANTS

Of 6872 offspring for whom maternal hemoglobin concentration was available, 57 had SSDs (0.8%) and 6815 did not (99.2%).

MAIN OUTCOME MEASURE

Prospectively assayed, the mean value of maternal hemoglobin concentration was the primary exposure. Hemoglobin concentration was analyzed as a continuous and a categorical variable.

RESULTS

A mean maternal hemoglobin concentration of 10.0 g/dL or less was associated with a nearly 4-fold statistically significant increased rate of SSDs (adjusted rate ratio, 3.73; 95% confidence interval, 1.41-9.81; P = .008) compared with a mean maternal hemoglobin concentration of 12.0 g/dL or higher, adjusting for maternal education and ethnicity. For every 1-g/dL increase in mean maternal hemoglobin concentration, a 27% decrease in the rate of SSDs was observed (95% confidence interval, 0.55-0.96; P = .02).

CONCLUSIONS

The findings suggest that maternal iron deficiency may be a risk factor for SSDs among offspring. Given that this hypothesis offers the potential for reducing the risk for SSDs, further investigation in independent samples is warranted.

Population-based cohort studies on premorbid cognitive function in schizophrenia

Many previous studies have found associations between poor cognitive function and schizophrenia. However, the majority of these studies used retrospective data, leading to the possibility of selection and recall biases. Retrospective studies are also unable to distinguish whether cognitive deficits exist prior to the onset of schizophrenia, suggesting that they are important in etiology, or following onset, suggesting that they are secondary to the disorder or its treatment. The current review used a systematic search strategy to identify and summarize the results of all studies that have used population-based cohorts to examine associations between prospectively collected data on premorbid cognitive functioning in childhood or adolescence and subsequent risk for schizophrenia. Three broad categories of study have addressed these questions: birth cohort designs with cognitive testing during childhood, army conscript designs with cognitive performance measured at conscription, and studies using school grades. Birth cohort and conscript studies are consistent in reporting strong associations between poor performance on cognitive batteries and increased risk of schizophrenia. Studies on school performance have been less consistent, although the largest such study showed strong associations across all school subjects. In conclusion, children and adolescents with poor cognitive abilities in childhood are at increased risk of schizophrenia. This suggests that poor cognitive function is either directly causal or associated with causal factors that are involved in etiology.

Attention and executive systems abnormalities in adults with childhood ADHD: A DT-MRI study of connections

Attention-deficit/hyperactivity disorder (ADHD) is hypothesized to be due, in part, to structural defects in brain networks influencing cognitive, affective, and motor behaviors. Although the current literature on fiber tracts is limited in ADHD, gray matter abnormalities suggest that white matter (WM) connections may be altered selectively in neural systems. A prior study (Ashtari et al. 2005), using diffusion tensor magnetic resonance imaging (DT-MRI), showed alterations within the frontal and cerebellar WM in children and adolescents with ADHD. In this study of adults with childhood ADHD, we hypothesized that fiber pathways subserving attention and executive functions (EFs) would be altered. To this end, the cingulum bundle (CB) and superior longitudinal fascicle II (SLF II) were investigated in vivo in 12 adults with childhood ADHD and 17 demographically comparable unaffected controls using DT-MRI. Relative to controls, the fractional anisotropy (FA) values were significantly smaller in both regions of interest in the right hemisphere, in contrast to a control region (the fornix), indicating an alteration of anatomical connections within the attention and EF cerebral systems in adults with childhood ADHD. The demonstration of FA abnormalities in the CB and SLF II in adults with childhood ADHD provides further support for persistent structural abnormalities into adulthood.

Intellectual Decline in Schizophrenia: Evidence from a Prospective Birth Cohort 28 Year Follow-up Study

It is well established that IQ is lower among persons with schizophrenia than in the general population. However, it remains unclear if there is deterioration beyond a premorbid deficit. In order to assess the question of IQ deterioration, we assessed persons pre- and-post psychosis, comparing those who developed schizophrenia with those who did not. Twenty six patients with schizophrenia and 59 normal controls, evaluated at age 7 in the prospective, longitudinal, National Collaborative Perinatal Project (NCPP), were re-tested approximately 28 years later. We assessed change in an estimate of IQ based on the Vocabulary and Block Design tests from the Wechsler intelligence scales. Persons who later developed schizophrenia were significantly impaired on IQ compared to controls at age 7, especially on measures of attention. At age 35, persons with schizophrenia demonstrated significant impairment and deterioration on both IQ sub-tests compared to controls. Because impairment occurs by early childhood and subsequent deterioration occurs at an unknown period, designs with more frequent assessment of IQ through the premorbid, prodromal and early phases of illness are required to identify the key period of decline. Future research on this sample will evaluate the prospective roles of family history and perinatal complications on cognition, and assess the specificity of these findings.

Prenatal drug exposure effects on subsequent vulnerability to drug abuse

Research has shown that both prenatal alcohol and tobacco exposure are associated with increased risk of significant adverse medical, developmental, and behavioral outcomes including substance abuse. Research on the outcomes of prenatal exposure to illicit drugs (PNDE) has also found increased physical and behavioral problems for gestationally drug-exposed children. However, a clear picture has not emerged on whether the consequences of PNDE are independent from those associated with having a substance abusing parent and whether PNDE increases vulnerability to drug abuse. Because of its typical co-occurrence with factors inherent in having a drug-abusing parent, PNDE is at least a marker of significant increased risk for a range of negative outcomes including greater vulnerability to substance abuse. Although a review of the relevant research literatures indicates that the direct consequences of PNDE appear to be generally both subtle and nonglobal, PNDE does appear to have negative developmental and behavioral outcomes, and there is evidence that it is a modest direct contributor to increased substance abuse vulnerability.

Modes of imprinted gene action in learning disability

BACKGROUND

It is now widely acknowledged that there may be a genetic contribution to learning disability and neuropsychiatric disorders, stemming from evidence provided by family, twin and adoption studies, and from explicit syndromic conditions. Recently it has been recognized that in some cases the presentation of genetic syndromes (or discrete aspects of disorders) is dependent on the sex of the transmitting parent. Such 'parent-of-origin effects' can be explained by a number of genetic mechanisms, a predominant one of which is genomic imprinting. Genomic imprinting refers to the parent of origin-specific epigenetic marking of an allele of a gene, such that for some genes it is mainly the maternally inherited allele only that is expressed, whereas for others expression occurs mainly from the paternal copy.

METHODS

Here we discuss the contribution of imprinted genes to mental dysfunction and learning disability, using clinical examples of association studies and explicit imprinting disorders (with particular emphasis to Angelman and Prader-Willi syndromes), and evidence from animal work.

RESULTS

Clinical and animal studies strongly suggest that imprinted genes contribute to brain functioning, and when the genes or epigenetic processes are disrupted, this can give rise to neuropsychiatric problems. Another system to which imprinted genes provide a large contribute is the placenta and foetal development. Epidemiological studies suggest that this is also a key area in which dysregulation can give rise to learning difficulties.

CONCLUSIONS

Disruption of imprinted genes, or the epigenetic processes controlling them, can contribute to learning disability. These effects can be divided into two types: direct effects, such as those seen in explicit imprinting disorders such as Angelman and Prader-Willi syndromes, and indirect effects as manifest via changes in foetal programming.

Whether ionizing radiation is a risk factor for schizophrenia spectrum disorders?

The neural diathesis-stressor hypothesis of schizophrenia, where neurobiological genetic predisposition to schizophrenia can be provoked by environmental stressors is considered as a model of the effects of exposure to ionizing radiation. Analysis of information from electronic databases (MEDLINE, PsycINFO, EMBASE, Current Contents, Elsevier BIOBASE) and hand-made search was carried out. There are comparable reports on increases in schizophrenia spectrum disorders following exposure to ionizing radiation as a result of atomic bombing, nuclear weapons testing, the Chernobyl accident, environmental contamination by radioactive waste, radiotherapy, and also in areas with high natural radioactive background. The results of experimental radioneurobiological studies support the hypothesis of schizophrenia as a neurodegenerative disease. Exposure to ionizing radiation causes brain damage with limbic (cortical-limbic) system dysfunction and impairment of informative processes at the molecular level that can trigger schizophrenia in predisposed individuals or cause schizophrenia-like disorders. It is supposed that ionizing radiation can be proposed as a risk factor for schizophrenia spectrum disorders. The hypothesis that ionizing radiation is a risk factor for schizophrenia spectrum disorders can be tested using data from the Chernobyl accident aftermath. Implementation of a study on schizophrenia spectrum disorders in Chernobyl accident victims is of significance for both clinical medicine and neuroscience.

Is psychosis a neurobiological syndrome?

OBJECTIVE

To describe theoretical weaknesses in the DSM-IV criteria for psychotic disorders and to argue that schizophrenia-like psychosis is a neurobiological syndrome similar to aphasia or apraxia.

METHOD

We outline the criteria for the concept of neurobiological syndrome and present supporting evidence for schizophrenia-like psychosis as a neurobiological syndrome.

RESULTS

There is evidence in the literature to support the hypothesis that schizophrenia-like psychosis is a neurobiological syndrome.

CONCLUSION

Conceptualizing schizophrenia-like psychosis as a neurobiological syndrome has important implications for both clinicians and researchers.

Neurodevelopmental outcome at 8 months and 4 years among infants born full-term small-for-gestational-age

OBJECTIVES

To examine the association between intrauterine growth restriction and neurodevelopmental outcome among full-term small-for-gestational-age (SGAT) infants at 8 months and 4 years of age.

STUDY DESIGN

Growth parameters at birth and test scores on measures of neurodevelopmental function for 3922 children born SGAT were compared with those of 29,369 children born appropriately grown-for-gestational-age term from similar economic backgrounds. Additional within-SGAT/economic group comparisons were made for 1684 SGAT infants with symmetric undergrowth at birth and 2034 SGAT infants with asymmetric undergrowth at birth.

RESULTS

Regardless of socioeconomic background, infants born SGAT were found to be at significantly increased risk for neurodevelopmental difficulties at 8 months and at 4 years of age. Few within SGAT/socioeconomic group differences in neurodevelopmental outcome appeared to be associated with specific pattern of growth restriction at birth.

CONCLUSIONS

The present findings provide further evidence of the individual and public health impact of SGAT birth.

A brief neuropsychological testing battery for evaluating patients with schizophrenia

Current conceptualizations of schizophrenia include neurocognitive impairment, particularly in aspects of attention, memory, and executive functioning. Evaluation of these cognitive abilities typically involves use of comprehensive batteries which may take up to six hours to complete. The current study examined the effectiveness of a briefer battery to detect cognitive impairments usually seen in schizophrenia as established by previous studies using more lengthy and labor intensive protocols. The current study involved 61 outpatients with schizophrenia who were separated into three subgroups: paranoid type (n = 20), undifferentiated type (n = 21), and schizoaffective (n = 20). The majority of the patients were male (61%), African-American (52%), and of low socio-economic status. The mean age was 41.4 years (SD = 8.8), and the mean years of education was 11.7 (SD = 6.8). For the overall sample, results revealed mild to moderate impairments in memory, construction, concept formation, response set maintenance, psychomotor speed, and visual speed of information processing. Post-hoc analyses revealed significant differences between subgroups on Similarities and psychomotor speed, with the undifferentiated group performing more poorly than the paranoid or schizoaffective groups. In conclusion, the current brief battery minimized respondent burden in terms of both time demands and level of task complexity. However, it was also sensitive enough to capture many of the same cognitive weaknesses as those reported when using more labor-intensive neuropsychological test protocols.

Associations between premorbid intellectual performance, early-life exposures and early-onset schizophrenia. Cohort study

BACKGROUND

Impaired intellectual performance is associated with an increased risk of schizophrenia.

AIMS

To investigate whether this association is due to the influence of prenatal and early childhood exposures on both intellectual development and the risk of schizophrenia.

METHOD

Cohort of 197 613 Swedish male conscripts with linked birth, census and hospital admission data together with five measures of verbal and non-verbal intellectual performance recorded at conscription.

RESULTS

109 643 subjects had complete data; over a mean 5-year follow-up, 60 developed schizophrenia and 92 developed other non-affective psychoses. Poor scores for each of the five tests were associated with 3- to 14-fold increased risk of psychosis, particularly schizophrenia. Controlling for birth-related exposures, including birth weight, and parental education did not attenuate these associations.

CONCLUSIONS

Poor intellectual performance at 18 years of age is associated with early-onset psychotic disorder. Associations do not appear to be confounded by prenatal adversity or childhood circumstances, as indexed by parental education.

Academic achievement of low birthweight children at age 11: the role of cognitive abilities at school entry

We examine the extent to which deficits in academic achievement in low birthweight (LBW) children at age 11 are explained by deficits in cognitive abilities at school entry. Data come from a longitudinal study of a stratified sample of LBW and normal birthweight (NBW) children from an innercity and middle class suburbs in the Detroit area. Woodcock-Johnson Psychoeducational Battery-Revised was used to measure reading and math at age 11. WISC-R and specific neuropsychologic tests were administered at age 6. On reading, the LBW-NBW difference was -3.6 points (SE = 1.2). The difference was explained almost entirely by IQ at age 6. On math, the LBW-NBW difference was -6.1 points (SE = 1.1). The difference on math was trivial and not significant, when IQ and neuropsychological tests at age 6 were controlled. Level of LBW was unrelated to reading, but it had a gradient relationship with math, with birthweight < or = 1,500 g associated with a greater deficit than heavier LBW. The results imply that most of the LBW-NBW gap in academic achievement at age 11 could be eliminated by eliminating differences in cognitive abilities at age 6. Interventions to improve academic performance of LBW children should focus on the preschool years.

Prenatal tobacco effects on neuropsychological outcomes among preadolescents

This study evaluated the relationships between maternal smoking during pregnancy and 10-year-old children's performance on measures of learning, memory, and problem-solving. In this prospective cohort study, mothers were recruited from an urban prenatal clinic in 1982 and 1983 and observed from their fourth prenatal month until the time of the study. At the 10-year visit, 593 children and mothers were evaluated. The prevalence of tobacco use was high in this cohort: 54.3%, 53.3%, and 60% of the women smoked in the first trimester, third trimester, and 10-year assessment, respectively. After controlling statistically for other prenatal substance use, current tobacco, other substance use variables, and multiple sociodemographic covariates, prenatal tobacco exposure was significantly associated with deficits in learning and memory. Specifically, prenatal tobacco exposure was associated with deficits in verbal learning and design memory, as well as slowed responding on a test of eye-hand coordination. In addition, these children demonstrated a reduced ability for flexible problem solving and more impulsivity, as indicated by an increase in perseverative responses on a card-sorting test. Prenatally exposed children did not show attention deficits or increased activity on a continuous performance test.