Birth weight and cognitive function in early adulthood: the Australian Aboriginal birth cohort study

Small for gestational age and anthropometric body composition from early childhood to adulthood: the Aboriginal Birth Cohort study

Background

In Australia the estimated rate of small for gestational age (SGA) births is 9% among non-Indigenous births compared to 14% among Aboriginal and Torres Strait Islanders. There is limited research investigating the effect of being born SGA on body composition later in life in Indigenous Australians.

Methods

Using data from the Aboriginal Birth Cohort longitudinal study, we compared the body composition of those born SGA to non-SGA by analysing anthropometric measures (height, weight, waist circumference, fat percentage [FAT%], body mass index [BMI], waist-to-height ratio, and A body shape index [ABSI]) collected at four follow-up periods (from childhood to adult). For cross-sectional analyses, linear regression models were employed to assess factors associated with anthropometric measures. For longitudinal analyses linear mixed models were employed to assess differences in anthropometric measures among SGA versus non-SGA individuals while adjusting for repeated measures.

Results

The analytic baseline cohort were those who participated in Wave 2 (n = 570). In cross-sectional analyses, across all waves those born SGA had smaller anthropometric z-scores compared to non-SGA individuals (β ranging from -0.50 to -0.25). Participants residing in urban environments were significantly larger in Waves 2 to 4 (β ranged 0.26 to 0.65). Those born SGA had higher ABSI scores in Waves 2 and 4 (β 0.26 and 0.37, respectively). In longitudinal analyses, those born SGA had smaller measures of body composition across the life course; these differences were larger in urban communities. In remote communities those born SGA had significantly higher ABSI scores during adolescence and young adulthood, and this difference was not observed in urban communities.

Conclusion

Indigenous Australians born SGA are smaller anthropometrically later in life compared to their non-SGA counterparts. In remote communities, those born SGA had higher levels of central adiposity compared to non-SGA.

Mendelian randomization suggests that head circumference, but not birth weight and length, associates with intelligence

INTRODUCTION

Birth parameters have long been reported to have a role in human intelligence. However, the causalities reported in previous observational studies were controversial. Our study aims to provide an unbiased investigation of the causal associations between birth parameters and human intelligence using the Mendelian randomization (MR) approach.

METHODS

Genetic instrumental variables for MR analyses were extracted from large genome-wide association studies of infant head circumference (N = 10,768), birth length (N = 28,489), and birth weight (N = 321,223). Data for intelligence were obtained from a meta-analysis of genome-wide association studies of 269,867 individuals of the European ancestry. Primary MR analysis was performed using the standard inverse-variance weighted method, and sensitivity analyses were performed using the weighted median, MR-Egger, and MR-PRESSO methods.

RESULTS

Using 10 single nucleotide polymorphisms as instrumental variables, we found that 1 standard deviation increase in infant head circumference was associated with 0.14-fold higher scores in intelligence tests (β = 0.14, 95% confidence interval: 0.09 to 0.18, P_IVW =2.05 × 10^-9 ). The causal relationship was robust when sensitivity analyses were performed. However, birth length and birth weight had no significant associations with intelligence.

CONCLUSION

Our findings suggested infant head circumference, but not birth weight and length were associated with intelligence, which might indicate that brain development rather than general fetal growth was responsible for the development of intelligence.

Harmonised collection of data in youth mental health: Towards large datasets

OBJECTIVE

The current international trend is to create large datasets with existing data and/or deposit newly collected data into repositories accessible to the scientific community. These practices lead to more efficient data sharing, better detection of small effects, modelling of confounders, establishment of sample generalizability and identification of differences between any given disorders. In Australia, to facilitate such data-sharing and collaborative opportunities, the Neurobiology in Youth Mental Health Partnership was created. This initiative brings together specialised researchers from around Australia to work towards a better understanding of the cross-diagnostic neurobiology of youth mental health and the translation of this knowledge into clinical practice. One of the mandates of the partnership was to develop a protocol for harmonised prospective collection of data across research centres in the field of youth mental health in order to create large datasets.

METHODS

Four key research modalities were identified: clinical assessments, brain imaging, neurocognitive assessment and collection of blood samples. This paper presents the consensus set of assessments/data collection that has been selected by experts in each domain.

CONCLUSION

The use of this core set of data will facilitate the pooling of psychopathological and neurobiological data into large datasets allowing researchers to tackle important questions requiring very large numbers. The aspiration of this transdiagnostic approach is a better understanding of the mechanisms underlying mental illnesses.

Can the gap in Aboriginal outcomes be explained by DOHaD

In Australia, there are two distinct populations, each with vastly disparate health outcomes: Aboriginal and Torres Strait Islander People and non-Aboriginal Australians. Aboriginal Australians have significantly higher rates of health and socioeconomic disadvantage, and Aboriginal babies are also more likely to be born low birth weight or growth restricted. The Developmental Origins of Health and Disease (DOHaD) hypothesis advocates that a sub-optimal intrauterine environment, often manifested as diminished foetal growth, during critical periods of foetal development has the potential to alter the risk of non-communicable disease in the offspring. A better understanding of the role of the intrauterine environment and subsequent developmental programming, in response to both transgenerational and immediate stimuli, in Aboriginal Australians remains a relatively unexplored field and may provide insights into the prevailing health disparities between Aboriginal and non-Aboriginal children. This narrative review explores the role of DOHaD in explaining the ongoing disadvantage experienced by Aboriginal People in today's society through a detailed discussion of the literature on the association between foetal growth, as a proxy for the quality of the intrauterine environment, and outcomes in the offspring including perinatal health, early life development and childhood education. The literature largely supports this hypothesis and this review therefore has potential implications for policy makers not only in Australia but also in other countries that have minority and Indigenous populations who suffer disproportionate disadvantage such as the United States, Canada and New Zealand.

Neurodevelopment at Age 10 Years of Children Born <28 Weeks With Fetal Growth Restriction

OBJECTIVES

We sought to evaluate the relationships between fetal growth restriction (FGR) (both severe and less severe) and assessments of cognitive, academic, and adaptive behavior brain function at age 10 years.

METHODS

At age 10 years, the Extremely Low Gestational Age Newborns Cohort Study assessed the cognitive function, academic achievement, social-communicative function, psychiatric symptoms, and overall quality of life of 889 children born before 28 weeks' gestation. A pediatric epileptologist also interviewed parents as part of a seizure evaluation. The 52 children whose birth weight z scores were <-2 were classified as having severe FGR, and the 113 whose birth weight z scores were between -2 and -1 were considered to have less severe FGR.

RESULTS

The more severe the growth restriction in utero, the lower the level of function on multiple cognitive and academic achievement assessments performed at age 10 years. Growth-restricted children were also more likely than their extremely preterm peers to have social awareness impairments, autistic mannerisms, autism spectrum diagnoses, difficulty with semantics and speech coherence, and diminished social and psychosocial functioning. They also more frequently had phobias, obsessions, and compulsions (according to teacher, but not parent, report).

CONCLUSIONS

Among children born extremely preterm, those with severe FGR appear to be at increased risk of multiple cognitive and behavioral dysfunctions at age 10 years, raising the possibility that whatever adversely affected their intrauterine growth also adversely affected multiple domains of cognitive and neurobehavioral development.

Performance of the CogState computerized battery in the Mayo Clinic Study on Aging

INTRODUCTION

The feasibility and validity of brief computerized cognitive batteries at the population-level are unknown.

METHODS

Nondemented participants (n = 1660, age 50-97 years) in the Mayo Clinic Study on Aging completed the computerized CogState battery and standard neuropsychological battery. The correlation between tests was examined and comparisons between CogState performance on the personal computer (PC) and iPad (n = 331), and in the clinic vs. at home (n = 194), were assessed.

RESULTS

We obtained valid data on greater than 97% of participants on each test. Correlations between the CogState and neuropsychological tests ranged from -0.462 to 0.531. Although absolute differences between the PC and iPad were small and participants preferred the iPad, performance on the PC was faster. Participants performed faster on Detection, One Card Learning, and One Back at home compared with the clinic.

DISCUSSION

The computerized CogState battery, especially the iPad, was feasible, acceptable, and valid in the population.