There's no single test for ADHD and they have to go through a process of elimination and rule out other things first that may be causing the issues. ADHD was at one time a diagnosis given to a small number of children and now it gets described as being at epidemic levels.
My oldest son was assessed for ADHD when he was five and attending an unusually good public school in a small city with a big university where there was enormous competition for teaching positions by qualified people. They concluded he had some kind of attention span issue, but it wasn't ADHD because he weirdly paid more attention to longer, more complex sentences and they had no idea what that meant.
Years later while involved with the gifted community online, I dubbed that Bored Gifted Kid Syndrome. Prior to that, at one school his frustrated teacher said we should "Put him on Ritalin." to control his behavioral issues and made no mention of assessment for ADHD and didn't bother to ask if he had already been assessed for it.
He also had an undiagnosed medical condition that contributed to his problems and getting an appropriate diagnosis helped me get him more generally functional which improved attention span and generally improved social function.
The fact that we had some kind of assessment that ruled it out is why I know they are supposed to rule out other explanations. I have some firsthand experience with the process for assessing ADHD.
So I tried to search this online and I had technical difficulties and failed to copy and paste what it said, but the initial Internet reply to my query about it being a diagnosis of last resort said "NO! It's a real neurodevelopmental issue!"
It also said:
1. There's no single test for it.
2. You first need to check for this extremely long list of possible other explanations.
So I call bullshit.
Because I have a genetic disorder and there's a TEST for it. They don't FIRST need to ELIMINATE other explanations and then say "Well, given the lack of other explanations, we shall assume it's this disorder!" even though in practice, because I have a mild form of it, I got tested for all kinds of things before I got the RIGHT test.
But once I had the right test I knew it was right because reading up on the underlying mechanism for my condition was hugely game changing and I grew a lot healthier. I still get called crazy and told there's nothing wrong with me, but actual reality disagrees with fools on the Internet wanting to say I'm merely a histrionic drama queen or some nonsense.
So if you CANNOT identify a specific thing as "ADHD" and cannot figure out a means to test for that specific thing and you are supposed to first eliminate other explanations before giving it that label, I am very skeptical this is a distinct neurological condition rather than simply a potential symptom of various things.
I'm not saying you don't have a real problem. I'm saying we came up with this kind of catch-all term for attention span problems we can't really explain and initially it was a really small number of kids who got that label and now it's "an epidemic." Because while we don't have a definitive test, it's convenient to slap a label on it and "Give the kid Ritalin" for the convenience of aggravated teachers and parents and daycare workers.
I tripped across this piece about why ADHD drugs should be a last resort and skimmed it. ADHD drugs can be very dangerous and we are giving them out like candy not for the welfare of children but for the convenience of aggravated adults in their lives and this can actively create permanent long-term brain issues and other serious medical issues.
Years ago, I read that one condition that can be misdiagnosed as ADHD involves inadequate blood flow to specific parts of the brain and certain ADHD drugs suppress blood flow to those parts of the brain. That scares the hell out of me as a possible WHOOPSIE! for a growing child.
We have a global issue where poor soils and overuse of chemical fertilizers has fostered a steady decline in nutritional value of produce and we have widespread food deserts in the US where people have significant challenges in getting adequate nutrition. And I imagine a teacher eager to say "Put him on Ritalin." is not bothering to wonder if the kid is living on sugary colas and microwaved garbage or simply poor and underfed generally.
Improving nutritional status for my medically handicapped child did wonders for his attention span and social issues. I have the same condition and was never deemed to be a candidate in school for anything like ADHD but rest assured when I'm under the weather, I sometimes have the attention span of the proverbial squirrel on crack.
I grew up decades earlier and nutritional value of food has steadily declined since then. So perhaps I performed better in part because food used to be inherently more nutritious.
I used to spend time in various online parenting spaces for parents of children with various problems. I gave my son nutritional supplements that improved a lot of his issues and I spoke with parents of other kids who reported similar success and sometimes posted studies supporting the idea that nutritional supplements were more effective than most ADHD drugs.
Bonus points: They are generally safer and cheaper too.
Why do we give drugs instead?
Probably in part because nutrition is extremely hard to study. Most nutritional studies roughly follow this format:
1. It's self reported data.
2. It's correlation without proof of causation.
3. It's very general in a way that inherently provides no means to tease out what the important difference is.
What they typically do is something like ask ten thousand nurses -- because nurses theoretically are knowledgeable and making informed dietary choices -- to self report on eating habits for a few months and they draw conclusions like "Super healthy smarty pants nurses typically eat more nuts than the rest of you MORONS, so nuts must be Good For You (TM) and don't confuse us with the facts that there may be ten thousand other explanations for why they suck less than you AND let's not get into specific nutrients in those nuts, no."
In contrast, I and parents I spoke with typically added a specific nutrient via supplement, not a food and not a multivitamin, and we were talking to other people who could tell us what nutrient we should add for which issues.
It's also vastly more profitable to prescribe drugs and more convenient to give a little pill than try to fix his diet and more socially acceptable to tell a parent "It's not your fault! Some kids are just BORN this way and we can help you!" than to ask how well they feed the kid.
We medicalize things instead of trying to have a functional society and functional family unit and adequate nutrition. And then we are BAFFLED by what a debacle our world is.