Late-diagnosed autism may be a different form, study finds
A large international study suggests that autism diagnosed later in life could represent a distinct form of the condition, separate from autism identified in early childhood. The research, published in Nature, analyzed thousands of individuals from Denmark and the United States to explore whether late diagnoses reflect a milder, overlooked version of early autism or a fundamentally different condition.
The study examined two competing theories. One posits that all people with autism share a similar genetic foundation, and late diagnoses arise when symptoms are milder or less noticeable, only becoming prominent later. The other theory, supported by the study, argues that autism diagnosed in childhood and autism diagnosed much later may indeed be different forms of the broader spectrum.
The genetic finding
Researchers found significant genetic differences between those diagnosed early and those diagnosed later in life. In particular, the late-diagnosis group showed genetic profiles that were more similar to attention deficit hyperactivity disorder (ADHD) than to early-diagnosed autism. This genetic divergence suggests that late-diagnosed autism is not simply a subdued version of childhood-detected autism, but may constitute a separate subtype with its own biological underpinnings.
Mental health and care implications
The study also identified a higher risk of mental health conditions, including depression, among people diagnosed later. These findings underscore the need for personalized approaches to care, with attention to the broader mental health profile that can accompany late-diagnosed autism. Doctors and caregivers are encouraged to tailor assessments and interventions to the individual’s unique genetic and psychological landscape rather than applying a one-size-fits-all model.
Experts weigh in
Lead researchers emphasize that autism is highly heterogeneous: people on the spectrum are very different from one another. The team’s work supports the idea of treating each patient as a distinct case with specific needs and potential subgroups within autism that may warrant different diagnostic labels in the future.
Uta Frith, an emeritus professor of cognitive development at University College London, reflected on the study with cautious optimism. She noted that recognizing subgroups within autism could lead to more precise diagnoses and appropriate treatments as science advances. The study’s authors also highlighted that, while discussing an “epidemic” or a universal cure or cause is tempting, the real question for science and medicine is which kind of autism is being referenced.
Context amid public discourse
The findings arrive as public discourse around autism becomes entangled with misinformation. In some political circles, claims have circulated about an autism “epidemic” and unfounded links to vaccines or common medicines. The new research provides a reminder that autism is not a single disease but a spectrum with diverse biological roots and trajectories, reinforcing the need for evidence-based understanding and care.
What this means going forward
As diagnostic criteria broaden, more individuals may be identified later in life. The study’s authors call for continued research to map the different subtypes within autism and to develop targeted diagnostic labels that reflect distinct genetic and clinical profiles. Such work could ultimately improve outcomes by guiding personalized interventions that align with each person’s unique needs and risks.
In sum, late-diagnosed autism appears to be more than a delayed version of early autism. It may represent a separate form with its own genetic signature and mental health considerations, reinforcing the importance of nuanced, individualized care for every person on the autism spectrum.
