A study shows that autism diagnosed earlier versus later in life may reflect different developmental pathways and genetic profiles. In longitudinal data from four birth cohorts, there were two distinct socioemotional and behavioral trajectories tied to age at autism diagnosis. Genetic factors explained about 11% of the variation in when autism is diagnosed, a contribution similar to sociodemographic and clinical influences. Importantly, the study identified two autism polygenic factors: one linked to earlier diagnosis and lower social and communication abilities in early childhood, with only moderate genetic correlation with attention deficit–hyperactivity disorder (ADHD) and mental health conditions, and another linked to later diagnosis, marked by socioemotional and behavioral challenges in adolescence, and stronger genetic ties to ADHD and mental health conditions. These findings suggest that earlier- and later-diagnosed autism follow different developmental and genetic patterns, offering a new framework to better understand the diversity within autism. Developmental timing is just one possible axis along which autism subtypes can be differentiated, while other mechanistically separable subtypes of autism exist that have yet to be identified. Source: https://www.nature.com/
