Recent research reveals that the timing of autism diagnosis reflects underlying genetic and developmental differences, with early-diagnosed autism linked to traits present from childhood, and late-diagnosed autism associated with genetic factors emerging during adolescence.

These findings challenge the notion of autism as a single, unified condition, suggesting it may encompass multiple conditions with distinct genetic and developmental origins.

An international study involving over 45,000 individuals across Europe and the US found that those diagnosed before age six tend to have stable behavioral difficulties and specific genetic markers, while those diagnosed after age 10 often face increasing challenges and higher risks of mental health issues like depression.

The two developmental trajectories are not entirely separate but exist on a continuum, with some overlap, and neither should be considered more severe or milder than the other.

Factors such as sex and socioeconomic status have a weak influence on the age of diagnosis, explaining less than 10% of the variance, indicating other factors are more significant.

Longitudinal analysis using growth mixture models in three cohorts identified two behavioral trajectories: one with early, stable difficulties and another with difficulties that increase later, both correlating with age at diagnosis.

The study emphasizes the importance of accurate scientific understanding, dismissing misinformation linking autism to vaccines or paracetamol.

Clinically, individuals diagnosed later tend to be more vulnerable to psychiatric conditions such as depression, highlighting different clinical profiles based on diagnosis age.

The nearly 800% rise in autism diagnoses in the UK between 1998 and 2018 is attributed to broader diagnostic criteria and increased recognition of the condition.

Autism symptoms include persistent social communication difficulties and restricted behaviors, with diagnosis criteria emphasizing early childhood presentation, though the age of diagnosis varies widely.