Connecting autism-linked genetic variation to toddler social conduct | Spectrum
Anna Gui
Postdoctoral researcher, Birkbeck, University of London
Emily Jones
professor, Birkbeck, University of London
Advances in genetics have revolutionized our understanding of the origins of autism. We know that hundreds of genes with different functions can contribute to the disease, and many of these genes primarily affect the formation of the brain during prenatal and early postnatal development. But we still do not fully understand how these genetic factors are reflected in the behavioral signs of autism in early childhood.
Genetic changes can affect how the brain develops and processes information about the environment from conception, which in turn could affect a child’s later interests and behaviors – an effect that can only be discovered through examination of infants. Studies following Baby Sibs – infants who have an older sibling with autism and are therefore more likely to be on the spectrum – have identified changes in early brain and cognitive development that precede a diagnosis of autism. These changes include changes in the wiring and structure of the brain that translate into different ways an infant reacts to its surroundings.
One such difference is a brain response called N290, a surge in electrical activity that occurs about 290 milliseconds after a child has viewed a picture. Our group has unpublished evidence that non-autistic infants have a later N290 response to images of faces compared to non-facial images, suggesting that their brains linger on faces, but infants later diagnosed with autism Do not process faces and non-faces differently. How this difference in the N290 and other changes related to the genetic variation associated with autism was unclear.
In a study published in June, we incorporated genetic analysis into an investigation of the N290 response in baby siblings. This enabled us to identify the brain changes associated with the major genes and traits associated with autism. The approach can also reveal opportunities for intervention.
Our study focused on N290 responses as it is a marker of attention to social information, which is an important candidate for the way in which genetic factors may contribute to autism characteristics. Attention is a gateway to learning, and paying attention to other people provides babies with critical access to the information they need to learn about the social world. Genetic changes in social attention could affect early social learning and development in autistic children. Indeed, studies have shown that other measures of social engagement are highly heritable, that parental measures of social interaction are related to brain measures of social engagement in their infants, and that changes in social engagement anticipate a diagnosis of autism.
Face time:
We used electroencephalography to measure the rate of the N290 response in 81 babies and 22 infants with no family history of autism when the children were 6 to 10 months old. We also calculated each baby’s “polygenic score,” the sum of all common genetic variants associated with autism and other diseases in their DNA.
Baby siblings with a higher genetic predisposition to autism and other diseases had a shorter N290 response to faces than to images without faces. This work confirms that autism-related genes can contribute to autism traits by altering the brain’s responses to social information during the first year of life. Our work also supports the idea that polygenic scores can help uncover causal relationships between characteristics of autism and the disease itself.
Our study is part of a prospective longitudinal study called the British Autism Study of Infant Siblings, which tracks baby siblings from infancy to mid-childhood, combining behavioral assessments with neuroimaging and biometric techniques. Linking these measurements to differences in DNA helps us understand how genes affect brain development in order to influence behavior. For example, we plan to test the association between polygenic scores and brain activity measured when infants watch videos of social scenes or take part in real-world interactions, both of which might better reflect infants’ everyday experiences.
We continue to guide the babies as they grow and are screened for autism and other disorders and how early brain development, behavior, and genetics of the children are related to their diagnostic outcomes. In a study using eye tracking technology of more than 300 infants, we found that prolonged glances at an image of a face presented alongside other images with polygenic attention deficit hyperactivity disorder (ADHD) scores and not were associated with autism. Interestingly, this eye tracking indicator of reduced flexibility in gaze shifts was also associated with increased features of ADHD, but not with autism at the age of 6.
As we begin to study the effects of genetics on early brain development, we must also consider the ethical and societal implications of our work. Such associations do not imply any deterministic changes that predestine a child for an immutable future. Rather, we believe that identifying early brain changes associated with certain genetic profiles should be used as a starting point to study the environmental changes a child needs to develop optimally. In fact, early interventions that enrich a child’s social environment and help them connect with others can alleviate some of the difficulties associated with autism over time.
In the longer term, understanding the effects of genetics on the developing brain should create a new urgency to determine the optimal environments for children with different genetic profiles and optimize their developmental pathways.
Anna Gui is a postdoctoral fellow in psychological sciences at the Center for Brain and Cognitive Development at Birkbeck, University of London in the UK. Emily Jones is Professor of Translational Neurodevelopment at the Center.
Quote this article: https://doi.org/10.53053/IZSQ9571
