Over the years, language difficulties have been thought to be a core component of autism, a condition marked by difficulties with social communication and behavioural inflexibility. Yet the most recent edition of the Diagnostic and Statistical Manual, the DSM-5, has removed these symptoms from the criteria for autism, and studies of language ability in individuals with autism point towards considerable variability in this domain.

Recent research conducted by GEL lab members Dr Mark Taylor and Dr Angelica Ronald, along with their collaborators (Prof Tony Charman [King’s College London], Dr Elise Robinson [Harvard], Dr Emma Hayiou-Thomas [University of York], Prof Francesca Happé [King’s College London], and Prof Philip Dale [University of New Mexico], aimed to examine the relationship between autistic traits and language abilities using the classic twin design. Parents of twins taking part in the Twins Early Development Study (TEDS) rated the degree of autistic behaviours in the twins. The twins themselves completed four language tests over the internet.

The results were very surprising; autistic traits did not correlate strongly with performance on the four language tests. In addition to this, the genetic and environmental factors that caused autistic traits largely did not overlap with those influencing language abilities. This finding held when analyses were repeated on individuals displaying extreme scores (more similar to individuals with clinical diagnoses) on these measures. The results support the separation of language abilities from the core autistic traits.

You can read the paper, which is open access, here. The work has also been covered by SFARI.org.