Strengthening the evidence on the association of language difficulties with mental health problems across childhood and adolescence

Mental disorders are the leading causes of morbidity among youth in Europe. Critically, about 47% of youth accessing help for symptoms of mental health problems have moderate to severe language difficulties of unknown origin, i.e., not related with complex impairments of genetic or neurological origins such as Down syndrome or intellectual disabilities. Moreover, an average of 3 out of 30 pupils in a class, present language difficulties severe enough to affect their learning and socioemotional development. Given psychological therapies are grounded in the production and understanding of complex language - the very children who need help might be least able to benefit from it. It is thus imperative to understand why language difficulties and mental disorders co-occur so frequently. Do language difficulties cause mental disorders or can their co-occurrence be explained by other risk factors such as shared genes or environmental adversity? Drawing on existing population-based studies, the LaMMHa project will use innovative epidemiological methods to understand the bio-psycho-social mechanisms that explain the association between language difficulties and mental disorders in children and adolescents. It comprises of three complementary objectives: 1) to investigate the nature (correlational, causal, bidirectional) of the association between language difficulties and mental disorders in childhood and adolescence using longitudinal data from twin pairs 2) to investigate if language difficulties are a mediating factor explaining the association of early psychosocial adversity with mental health problems using causal mediation models; 3) to identify preventable psychosocial pathways linking language difficulties and mental disorders. The project will produce robust evidence with potential for translation in clinical work and prevention and will prepare the fellow to lead future epidemiological studies in a field critically lacking specialists.