Early vs Late Autism Diagnosis Reveal Distinct Genetic Paths
New findings from Cambridge University suggest autism may represent multiple neurodevelopmental conditions, not a single disorder.
A large international study finds that autism diagnosed in early childhood differs genetically and developmentally from autism identified later, suggesting distinct biological pathways that challenge the view of autism as one uniform condition.
Study Details:
Researchers from the University of Cambridge analyzed data from over 45,000 individuals across multiple cohorts to understand whether autism diagnosed early in childhood differs from cases identified later.
Autism, long regarded as a single neurodevelopmental spectrum disorder, has no known single cause and manifests differently among individuals. The researchers sought to determine whether these variations reflect distinct biological and developmental processes.
Methodology:
The team examined longitudinal data from four birth cohorts, each comprising between 89 and 188 autistic individuals. They combined developmental records tracking early social, motor, and language milestones with genetic analyses of rare and common variants.
Participants were grouped based on the timing of their autism diagnosis:
Early-diagnosed group: before age 7.
Later-diagnosed group: after age 7, including adolescents and adults.
Researchers compared developmental trajectories, coexisting mental health conditions, and genetic markers across the two groups.
Key Findings:
Early-diagnosed autism was associated with global developmental delay, intellectual disability, and significant motor and language deficits. These individuals carried more rare, deleterious genetic variants in constrained genes.
Later-diagnosed autism showed typical early development but emerging behavioral and cognitive challenges during later childhood or adolescence. These individuals had higher rates of ADHD and depression, with elevated polygenic risk scores for educational attainment and complex behavioral traits.
The genetic profiles of later-diagnosed individuals resembled those linked to ADHD, depression, and PTSD more closely than to early-diagnosed autism.
Experts from UCL and King’s College London emphasized that these findings highlight autism’s complexity and the likelihood of multiple mechanistic subtypes, rather than one overarching condition.
Implications for Practice:
For clinicians, these findings may encourage more nuanced diagnostic approaches, recognizing that autism’s presentation and genetic basis evolve across developmental stages.
For families, understanding that early- and late-onset autism differ biologically could refine expectations for intervention timing, educational planning, and comorbidity management.
Researchers caution that social and healthcare access factors still influence when individuals receive a diagnosis, underscoring the need for broader screening tools and diverse population studies.
Ultimately, this research could pave the way for personalized care models in autism where genetic and developmental profiling informs targeted therapies and support strategies.