The ADHD part is doing it constantly. Everyone loses stuff some times, ADHD people lose stuff all the time.
That’s the part that irks me when people pull the “oh but I do that so it’s not ADHD”. The difference isn’t if it does or doesn’t happen, it’s how often it happens and how much it impacts your day to day life.
It’s a bit of both with a healthy dose of “we’re not sure”. We know that ADHD brains don’t regulate neurotransmitters properly and that the theta vs beta waves are different, but there are a lot of other mechanisms we don’t understand.
Another great example is guanfacine. It’s primarily a blood pressure medication, but it also improves emotional regulation for ADHD patients. We think it improves connections in the prefrontal cortex, but we ultimately don’t have a solid understanding of why it actually helps.
Demand avoidance is a very common symptom of ADHD. If someone tells me I need to do something it instantly becomes very difficult to accomplish, no matter how much I myself want it done as well.
To be fair, ADHD is a developmental disorder that sometimes can present as delayed development rather than halted development. I.e being behind in executive functioning development but eventually “catching up” to peers.
That said, the severity of cases is still often determined through the lens of “how well do they fit in/mask it” and not “how is their emotional/mental wellbeing”, which definitely gives the impression of kids “growing out of it”.