Using genetic and environmental risks to understand variation in social, emotional, and educational outcomes in individuals with language impairments

Language Impairment (LI) is one of the most common childhood disorders. It is characterized by problems with using and understanding spoken language, in the absence of obvious causes such as deafness. The disorder is 'hidden', in that affected individuals do not have any marked visible features distinguishing them from other children. Among 5-year-olds, approximately 7% have LI - seven times more prevalent than autism. Children affected by LI often experience social, emotional health, and educational problems. As adults, many will struggle to find stable employment and are at increased risk of social dysfunction and mental health difficulties. Despite the serious implications of the condition for children and their families, LI is little known among the general community.

LI is a varied disorder, with different children manifesting different profiles of associated difficulties. Not all children go on to have poor outcomes. For example, some may have behavioural difficulties whilst others do not. Determining what makes different children vulnerable is challenging. The project will make use of genetic-risk information and data from the first 2 years of child's life (such as number of books in the household, socioeconomic status etc.) to classify children into sub-groups, using a statistical method known as latent class analysis. This will allow the investigation of whether belonging to certain sub-groups affects outcomes in middle childhood. For example, it may be that the children with a high genetic risk and a favourable home environment have comparable outcomes to those children with low genetic risk and a favourable home environment. If this does prove to be the case, it would suggest that genetic risk can be mitigated by a favourable home environment. This would provide evidence to target resources towards the most vulnerable children to improve their quality of life.

The project will also identify the pathways to poor outcomes in social adjustment, educational attainment and mental health functioning. For example, it may be that children with high genetic risk and a unfavourable home environment have behavioural difficulties and emotional problems in middle childhood. Pathway analyses afford the examination of multiple factors and different potential routes: how children may get from A to B. It also affords the evaluation of the strength of different pathways and the assessment of the extent to which outcomes in different areas of functioning derive from common or distinctive routes. Part of the strength of this proposal is the inclusion of a variety of factors: genetic, environmental, and psychological in the same model. The economic cost associated with language impairment has been estimated at 2.5% of gross national product. Evidence on the pathways to adverse outcomes will have wide ranging implications for public health measures and service provision.

This type of project requires large numbers of participants. Approval has been granted to use the Avon Longitudinal Study of Parents and Children (ALSPAC). This is an existing, epidemiological database that has records for ~7,000 children so no new data collection is needed for the project.