Different autism profiles identified according to age of diagnosis

The study, published in the journal Nature, highlights the discovery of two distinct genetic and developmental profiles associated with earlier and later autism diagnoses. It confirms that not only is autism highly heritable and a spectrum of conditions, but the age at diagnosis of autism is also heritable. The genetic data came from over 45,000 people across multiple international cohorts. The behavioural data however came from just four birth cohorts, with relatively small sample sizes (between 89 and 188 autistic individuals per cohort). These behavioural profiles were derived from the Strengths and Difficulties Questionnaire (SDQ), a general behavioural screening tool that does not capture detailed autistic and mental health traits and relies on caregiver reports rather than clinical assessments which limits the precision of the developmental trajectories described. Research in more diverse populations is needed to replicate the findings, with more detailed quality of life, everyday functioning and direct assessment measures.

The paper, the result of a high-powered international collaboration, demonstrates that autism is not a unitary condition. It makes clear that children diagnosed early and those diagnosed late form two very different subgroups. There is little overlap between them in terms of clinical features or genetics. It makes me hopeful that even more subgroups will come to light, and each will find an appropriate diagnostic label. It is time to realise that ‘autism’ has become a ragbag of different conditions. If there is talk about an ‘autism epidemic’, a ‘cause of autism’ or a ‘treatment for autism’, the immediate question must be, which kind of autism?