Evidence / 2015
Timing of the Diagnosis of Attention-Deficit/Hyperactivity Disorder and Autism Spectrum Disorder
Miodovnik A, Harstad E, Sideridis G, Huntington N (2015). Pediatrics.
- Population
- US children with both ADHD and autism diagnoses, National Survey of Children's Health 2011–2012
- Sample
- Survey sample of children with both diagnoses (see paper)
- Condition
- ADHD and autism; order of diagnosis
- Medication focus
- Not a treatment trial
- Jurisdiction
- United States
- Last reviewed
- 1 September 2026
- PMID
- 26347440
- DOI
- 10.1542/peds.2015-1502
Plain-language finding
Among children with both ADHD and autism diagnoses, those whose ADHD was identified first tended to receive an autism diagnosis later than children whose autism was identified from the outset. Sequential recognition is a documented pattern. A later autism diagnosis does not automatically mean the ADHD diagnosis was wrong.
Important limitation
US parent-survey data from 2011–2012. Recall and access bias apply. Timing of labels is not the same as timing of underlying difference. Not an Australian cohort.
Why we cite this
Empirical illustration that the order of diagnosis can delay a second recognition — a sequential pathway, not a contest between labels.
adhd · autism · sequential · overshadowing · late-diagnosis · nd-overlap
Research demonstrates a statistical relationship. Association is not causation. Timing, dose, confounding and missing data still matter.
Claims this source supports
Diagnostic overshadowing is the tendency to attribute symptoms automatically to an existing diagnosis, making another condition harder to recognise. The original experimental literature concerned intellectual disability. The same mechanism is clinically relevant when ADHD, autism or a psychiatric label becomes a ceiling on curiosity.
Last reviewed 1 September 2026
Different parts of a person's profile are often recognised at different points in life. In children with both ADHD and autism, those whose ADHD was identified first have been observed to receive an autism diagnosis later. A later diagnosis does not automatically invalidate an earlier one.
Last reviewed 1 September 2026
AuDHD is community language for autism and ADHD occurring together. It is not a separate DSM or ICD diagnosis with its own criteria. DSM-5 (2013) removed the earlier rule that had treated the two as mutually exclusive. Each condition still has to be assessed on its own terms. One does not automatically explain the other.
Last reviewed 1 September 2026