09/03/2026
Diagnostic overshadowing is one of the main reasons that so many Autistic and ADHD adults are missed for so long, often after a long string of other diagnoses.
Once something is on the chart, what follows tends to get read through it. For example, sensory overload can be interpreted as anxiety, restlessness as trauma, impulsivity as a mood disorder, and the second (or third) explanation never gets assessed. In AuDHD this can also happen between the two neurotypes, where the more visible one absorbs the clinical attention and the other stays in the background for years.
We can also misattribute mental health conditions to our neurodivergence, for example mistaking hypomania for ADHD traits, so it can go the other way too, where we miss mental health conditions.
For me, learning to tease apart my own experience (what is ADHD, what is autism, what is OCD, what is bipolar, what is anxiety) has been one of the more useful things I've done. The threads certainly still braid together and influence one another, and some days I can't tell which is which, but having the language for each one changes how I work with it. I respond differently to sensory overload than I do my anxiety. OCD checking gets a different response than ADHD checking and so on.
For more on diagnostic overshadowing and other core concepts, you can find the full NDI glossary up on our website (linked in comments).