Developmental Lay Summaries

2013

Slower language development in boys is associated with testosterone exposure before birth

Keywords: child, preschool, infant, language development, testosterone, vocabulary

What is already known about this subject:

  • Girls and boys learn to talk at different rates, with boys generally developing language more slowly than girls.
  • It is thought that exposure to higher levels of testosterone before birth may be responsible for the slower rate of language development in boys, but there have been very few studies that have directly investigated this.

What this Raine study adds:

  • Testosterone levels in umbilical cord blood samples and measures of expressive vocabulary at two years of age in Raine participants showed that boys had a smaller expressive vocabulary than girls at two years of age. Boys also had higher levels of umbilical cord blood testosterone.
  • Higher testosterone levels in umbilical cord blood were associated with a smaller vocabulary at two years of age in boys, but not in girls.
  • Exposure to sex hormones before birth influences language development, and the effects are different in males and females.

Hollier, L. P., Mattes, E., Maybery, M. T., Keelan, J. A, Hickey, M., & Whitehouse, A. J. O. (2013). The association between perinatal testosterone concentration and early vocabulary development: a prospective cohort study. Biological Psychology, 92(2), 212-5. doi:10.1016/j.biopsycho.2012.10.016. [publink]

Testosterone exposure before birth influences language development in boys via its effects on social interaction

Keywords: testosterone, language development, social and emotional engagement, vocabulary

What is already known about this subject:

  • Testosterone exposure before birth affects the developing brain and has been shown to influence language development.
  • Social interaction is essential for language development.
  • The effects of testosterone on language development may be related to its influence on the development of brain structures that control early social interaction, but this has never been directly tested.

What this Raine study adds:

  • Analysis of the relationship between umbilical cord testosterone levels, socio-emotional engagement at 1 year of age and vocabulary at 5 years of age in Raine participants showed that lower testosterone levels at birth were associated with better socio-emotional engagement and vocabulary development in boys but not in girls.
  • The effects of testosterone on vocabulary development in boys were found to be due to its effects on socio-emotional engagement.
  • These effects were small and couldn’t be detected once other factors including number of siblings, parental education and parent-child book reading were taken into consideration, suggesting that further investigation is warranted to help fully understand the relationship.

Farrant, B. M., Mattes, E., Keelan, J. A., Hickey, M., & Whitehouse, A. J. O. (2013). Fetal Testosterone, Socio-Emotional Engagement and Language Development. Infant and Child Development, 22(August 2012), 119-132. doi:10.1002/icd.1771. [publink]

Genes contributing to autism also contribute to the inheritance of autistic-like traits in the general population

Keywords: autism, genetic inheritance, genome-wide association study, young adults

What is already known about this subject:

  • Autism is a developmental condition characterised by difficulties with social communication.
  • The severity of autism varies widely, with some people experiencing more difficulties than others. Those at the severe end of the scale are diagnosed with Autism Spectrum Disorder, but people without this diagnosis can still have features of autism.
  • Autism is strongly genetically inherited, and it is thought that the same genes may be responsible for autistic-like traits in people with and without autism, although these genes have yet to be identified.

What this Raine study adds:

  • Genome-wide screening of DNA samples collected at 14-16 years of age and measurement of autistic-like traits at 20 years of age in non-autistic Raine participants found evidence supporting a role for two previously identified genes in the inheritance of autistic-like traits in the general population.
  • Studies investigating the genetic inheritance of autism need not only look at autistic individuals, but can include data from individuals at all levels of the spectrum and the general population.

Jones, R. M., Cadby, G., Melton, P. E., Abraham, L. J., Whitehouse, A. J., & Moses, E. K. (2013). Genome-wide association study of autistic-like traits in a general population study of young adults. Frontiers in Human Neuroscience, 7(October), 658. doi:10.3389/fnhum.2013.00658. [publink]

2012

Language problems in children whose mothers had low vitamin D levels during pregnancy

Keywords: behavioural problems, emotional problems, language impairment, brain development, vitamin D, pregnancy

What is already known about this subject:

  • Vitamin D levels in the general population have decreased considerably over the past decade, and as many as 60% of Caucasian women are deficient in vitamin D.
  • Low vitamin D levels during pregnancy can affect the health of the developing child, but the effects on brain and cognitive development are not yet clear.

What this Raine study adds:

  • Vitamin D levels in pregnant mothers participating in the Raine study and behaviour and language development data at 2, 5, 8, 10, 14 and 17 years of age in their children demonstrated a link between maternal vitamin D insufficiency during pregnancy and offspring language impairment.
  • There was no association with childhood behavioural or emotional problems.
  • The study contributes further evidence that prenatal levels of Vitamin D are important for optimal development.

Whitehouse, A. J. O., Holt, B. J., Serralha, M., Holt, P. G., Kusel, M. M. H., & Hart, P. H. (2012). Maternal Serum Vitamin D Levels During Pregnancy and Offspring Neurocognitive Development. Pediatrics, 129(3), 485-493. doi:10.1542/peds.2011-2644. [publink]

Children with poor language development have a smaller head circumference at birth

Keywords: language impairment, development, head circumference, fetal growth, child

What is already known about this subject:

  • Specific language impairment occurs in children who have difficulties with language, but have normal intelligence, hearing and access to education.
  • It is thought that specific language impairment may be due to abnormal brain development, but as diagnosis relies upon language milestones that usually occur between 3 and 5 years of age, there is very little data to support this.

What this Raine study adds:

  • Pregnancy and birth related data, including head circumference (as a marker of brain size) in Raine children with and without specific language impairment at 10 years of age showed that children with specific language impairment were more likely to have a small head circumference at birth, but not at 18 weeks gestation or as infants.
  • Brain development may be disrupted in specific language impairment.

Whitehouse, A. J. O., Zubrick, S. R., Blair, E., Newnham, J. P., & Hickey, M. (2012). Fetal head circumference growth in children with specific language impairment. Archives of Disease in Childhood, 97, 49-51. doi:10.1136/adc.2009.180331. [publink]

Anaesthesia exposure increases the risk of language problems in children

Keywords: anaesthesia, cognitive function, language development, brain development

What is already known about this subject:

  • Animal models have shown that exposure to anaesthetics can have a detrimental effect on the immature brain.
  • Studies investigating the effects of anaesthetic exposure in children have shown mixed results.
  • No studies to date have used directly administered neuropsychological assessments to assess the effects of anaesthetic exposure on young children.

What this Raine study adds:

  • Anaesthesia exposure data and data from neuropsychological testing at 10 years of age in Raine participants demonstrated that children exposed to anaesthesia before 3 years of age were at increased risk of problems with receptive and expressive language and abstract reasoning. One exposure was sufficient to increase the risk.
  • No problems were found in any of the other areas tested (cognition, behaviour, motor function).
  • Early exposure to anaesthesia has lasting effects on specific aspects of neuropsychological development.

Ing, C., DiMaggio, C., Whitehouse, A., Hegarty, M. K., Brady, J., von Ungern-Sternberg, B. S., … Sun, L. S. (2012). Long-term Differences in Language and Cognitive Function After Childhood Exposure to Anesthesia. PEDIATRICS. doi:10.1542/peds.2011-3822. [publink]

Androgen levels in umbilical cord blood are lower than previously thought and are influenced by fetal, maternal and obstetric factors

Keywords: androgens, sex hormones, umbilical cord blood, pregnancy, birth

What is already known about this subject:

  • Androgens (male sex hormones, including testosterone) have wide-ranging effects on cognition, behaviour and health.
  • Exposure to androgens before birth is usually measured using umbilical cord blood samples, however standard methods have recently been found to be inaccurate.
  • It is known that there are many pregnancy and birth-related factors that can affect fetal androgen levels, but their effects have not been accurately measured using appropriate techniques.

What this Raine study adds:

  • Fetal, maternal and obstetric data, together with androgen concentrations in umbilical cord blood collected at birth from Raine participants revealed that androgen levels in cord blood are lower than previously described.
  • Umbilical cord androgen levels differed between boys and girls, and were influenced by gestational age at delivery and whether or not labour occurred.
  • Accurate measurement of androgen levels in cord blood requires the use of appropriate techniques. Caution should be used in the interpretation of androgen data from older studies.

Keelan, J. A., Mattes, E., Tan, H., Dinan, A., Newnham, J. P., Whitehouse, A. J. O., … Hickey, M. (2012). Androgen concentrations in umbilical cord blood and their association with maternal, fetal and obstetric factors. PLoS ONE, 7(8), 1-10. doi:10.1371/journal.pone.0042827. [publink]

Worse verbal ability in children whose mothers experienced hypertensive disease during pregnancy

Keywords: cognition, gestational hypertension, pre-eclampsia, verbal ability, non-verbal ability

What is already known about this subject:

  • As many as 1 in 5 pregnant women experience high blood pressure. Hypertensive diseases of pregnancy can have serious consequences for both mother and child.
  • There is some evidence to suggest that hypertensive diseases of pregnancy can affect cognitive function in offspring, but data is limited and studies have not always shown a relationship.

What this Raine study adds:

  • Pregnancy data including hypertension and pre-eclampsia in mothers, and measures of verbal and non-verbal ability at 10 years of age in children participating in the Raine study demonstrated a small decrease in verbal ability in children whose mothers experienced hypertensive disease during pregnancy.
  • No relationship was observed between hypertensive diseases and non-verbal ability.
  • Given that hypertensive diseases are common during pregnancy; their role in children’s cognitive development is worth investigating further.

Whitehouse, A. J. O., Robinson, M., Newnham, J. P., & Pennell, C. E. (2012). Do hypertensive diseases of pregnancy disrupt neurocognitive development in offspring? Paediatric and Perinatal Epidemiology, 26, 101-108. doi:10.1111/j.1365-3016.2011.01257.x. [publink]

High testosterone exposure before birth affects language development differently in boys and girls; acts as a risk factor in boys, protective in girls

Keywords: testosterone, developmental language disorder, language delay, sex differences

What is already known about this subject:

  • Boys typically develop language skills more slowly than girls.
  • Exposure to testosterone is known to influence the developing brain.
  • It is not yet clear if early testosterone exposure is related language delay in children.

What this Raine study adds:

  • Testosterone levels in umbilical cord blood and developmental data at 1, 2 and 3 years of age in children participating in the Raine study revealed that boys with high levels of testosterone exposure had more than twice the risk of clinically significant language delay in the first 3 years of life.
  • In contrast, increasing testosterone levels reduced the risk of language delay in girls.
  • High prenatal testosterone levels are a risk factor for language delay in boys, but may be protective for girls.

Whitehouse, A. J. O., Mattes, E., Maybery, M. T., Sawyer, M. G., Jacoby, P., Keelan, J. A., & Hickey, M. (2012). Sex-specific associations between umbilical cord blood testosterone levels and language delay in early childhood. Journal of Child Psychology and Psychiatry and Allied Disciplines, 53, 726-734. doi:10.1111/j.1469-7610.2011.02523.x. [publink]

No relationship between testosterone exposure before birth and autistic traits

Keywords: autism, autistic-like traits, testosterone, perinatal, prenatal

What is already known about this subject:

  • Autism is characterised by difficulties with communication and social interaction together with a restricted range of activities and interests.
  • Boys are more likely to be autistic than girls.
  • There is some evidence to suggest that exposure to the male sex hormone testosterone before birth may contribute to the development of autism or features of autism, but the relationship is still unclear.

What this Raine study adds:

  • Assessment of autistic-like traits and testosterone levels in umbilical cord blood collected from Raine participants demonstrated no relationship between testosterone levels and autistic-like traits in the general (non-autistic) population.
  • There is no evidence to suggest that exposure to testosterone before birth is related to autistic traits.

Whitehouse, A. J., Mattes, E., Maybery, M. T., Dissanayake, C., Sawyer, M., Jones, R. M., Hickey, M. (2012). Perinatal testosterone exposure and autistic-like traits in the general population: a longitudinal pregnancy-cohort study. Journal of Neurodevelopmental Disorders, 4(1), 25. doi:10.1186/1866-1955-4-25. [publink]

Identification of a genetic region involved in dyslexia, brain structure and intelligence

Keywords: genetic inheritance, cognitive ability, risk factors, dyslexia

What is already known about this subject:

  • Dyslexia and specific language impairment are common disorders relating to literacy and language skills. Both are due to the combined influence of genetics and environment.
  • It is known that intelligence is strongly genetically inherited, but the actual genes involved have been difficult to identify.
  • Most of the risk genes for dyslexia and specific language impairment are involved brain development. It is not yet known if the influence of these genes on brain development also extends to a more general effect on intelligence.

What this Raine study adds:

  • DNA data from over 5000 individuals (including Raine participants), brain imaging scans and measures of verbal and non-verbal IQ showed that a genetic region associated with dyslexia is also associated with general intelligence.
  • A genetic region involved with language and general cognitive abilities was also found to be associated with brain structure.
  • This genetic region may influence intelligence by influencing brain development. Identifying the specific gene(s) involved may help to clarify the biological pathways involved in normal and abnormal brain function.

Scerri, Thomas S., Fahimeh Darki, Dianne F. Newbury, Andrew J O Whitehouse, Myriam Peyrard-Janvid, Hans Matsson, Qi W. Ang, et al. 2012. The Dyslexia Candidate Locus on 2p12 Is Associated with General Cognitive Ability and White Matter Structure. PLoS ONE 7 (11). doi:10.1371/journal.pone.0050321. [publink]

Multiple prenatal ultrasounds are not associated with an increased risk of autism

Keywords: autism, environment, obstetric, prenatal ultrasound scans

What is already known about this subject:

  • Autism spectrum disorder is characterised by problems with social interaction and communication and a restricted range of activities and interests.
  • While it is known that autism is caused by a combination of genetic and environmental factors, the biological pathways involved are not yet understood.
  • Current high rates of autism diagnoses are partly due to increased awareness and changes in the diagnostic criteria, but it is not known if increased exposure to some environmental factor may also be to blame.
  • Prenatal exposure to multiple ultrasound scans during pregnancy is a relatively recent phenomenon that may be associated with the increase in autism prevalence, but this has not been well studied.

What this Raine study adds:

  • Autism data collected at 5, 8, 10, 14, 17 and 20 years of age in Raine participants, together with ultrasound data collected during their mothers’ pregnancies revealed that having multiple ultrasound scans during pregnancy was not related to the development of autism.
  • Neither diagnoses of Autism Spectrum Disorder nor the level of autistic-like traits in participants without autism was increased in participants whose mothers who had 5 ultrasound scans compared to those who had a single ultrasound scan during pregnancy.
  • There is no obvious relationship between prenatal ultrasound scans during pregnancy and the development of autism.

Stoch, Yonit K., Cori J. Williams, Joanna Granich, Anna M. Hunt, Lou I. Landau, John P. Newnham, and Andrew J O Whitehouse. 2012. Are Prenatal Ultrasound Scans Associated with the Autism Phenotype? Follow-up of a Randomised Controlled Trial. Journal of Autism and Developmental Disorders 42: 2693-2701. doi:10.1007/s10803-012-1526-8. [publink]