I was just reading this thread, and thought I'd throw in my two cents.
I've had ADHD all my life. I only found out about it a few months ago at age 49.
I knew I was out of whack, but just put it down to laziness and stupidity (despite a high IQ, and having to work ten times as hard as anybody else just to get out of bed in the morning, let alone to put in a full day's work or study).
Yes, it's true. Everybody shows symptoms of ADHD from time to time. Every time you forget where you put your keys. Or you get distracted by something and have trouble focussing on what you're doing. This makes it a little tough to diagnose.
But people with ADHD have these symptoms 24 hours a day.
The diagnosis for ADHD used to also include "emotional dysregulation". But emotions are not quantifiable, so it was removed from the
DSM III (Diagnostic and Statistical Manual of Mental Disorders) definition of
ADHD, and still left out in the current DSM IV definition.
So everybody knows about the ADHD lack of focus, distractability etc. But not many people are aware of the emotional dysregulation, which is still a big part of ADHD, even if the text books no longer mention it. It certainly makes my life more difficult than it needs to be.
Basically, a person with ADHD will often stew over things for hours, days, weeks. The wheels are always turning in an ADHD brain. And if an emotional event such as negative criticism, guilt, failure, anger, embarassment or whatever kicks in, it can be difficult to switch those emotions off. The brain will just keep rehashing a conversation, or a thought, working it through. Thinking of what you could have said instead. Or just getting angrier and angrier about the injustice. Or withdrawing into your shell.
A person with ADHD may find it difficult to not overreact emotionally to things that normal people really wouldn't worry too much about.
Another main symptom of ADHD is a reduced working memory. It's like the rest of the world having 16gb of RAM when you only have 4gb. So if you are given a complex set of instructions to follow, an ADHD person will typically get a few steps into it, but forget what the other steps were. Because of the reduced working memory.
Add to that the fact that an ADHD brain picks up everything, and has problems filtering stimuli. For example, you notice a blue car driving past. That replays in your brain, reducing the amount of available working memory. Then a fly buzzes around your head, and that ends up in your working memory, displacing something else. Then a conversation from yesterday starts playing in your head.... By now you're lucky to have been able to remember up to step 3 of whatever you have to do for work, and you've no room left for the other 98 steps. So you ask the boss what comes next. The boss rolls their eyes (again) and says "I just told you what to do! You never listen... Nobody else has problems with this, you must be thick or lazy". And you find yourself getting all the dumb jobs.
As for diagnosis and meds... My own feeling is that if I was diagnosed earlier, I might have had a chance. I can't see any down side in knowing more about yourself. On the other hand, I can see a down side to other people knowing more about you.
In my own short experience of being on the meds, I found they improved certain aspects of my life. I found I could focus better, and even get up in the morning and feel actually awake. The stimulant meds work differently on ADHD people than they do on normal people. I actually pop half a tab of dexamphetamine if I'm having trouble getting to sleep because the wheels keep turning and I have thoughts floating around that I can't stop. The dexy slows the wheels, and allows me to get to sleep.
What killed me at that job wasn't the meds, it was my crew's knowledge that I had ADHD. This gave them a label for me, and it provided a focal point for any and all criticism, real or unjustified.
I'm still not 100% sold on the meds, they are certainly not a magic bullet. I still need to fine tune a few things, and maybe try a different medication to see if it works better. And a common saying is that "pills don't teach skills". I need to try some therapy or counselling (but can't afford them just now until I find work, and then I won't have time). Cognitive behavioural therapy seems to get good results. I need to learn some social skills, and other skills.
Another aspect of ADHD is that it rarely works alone. It seems to attract other mental illnesses. Commonly depression or anxiety. But also autism, bipolar, pretty much anything else.
But it's not all bad either. Motivation is a real problem for ADHD. If you are unmotivated, but forced to do something you are not enthusiastic about, you will have to work really, really hard just to get started. In fact, if somebody with ADHD tries to work harder to do something that they aren't motivated to do, the brain will actually start reducing the chemical (serotonin? Can't remember) which normally motivates you. So the harder you work, the less your brain rewards you, so the harder you have to work. Like trying to focus on your homework when your friends are outside your window having fun. It's harder to focus, and to push yourself to complete the work.
But I said it wasn't all bad. If an ADHD person IS motivated... Then the hyperfocus kicks in.
If I'm fired up, I can go for days without food or sleep, while I plug away at what I'm doing, with 10000% concentration. I can outperform anyone by a large margin. When I'm motivated and given free reign.
Also, ADHD people tend to think outside of the box. Sometimes, I can't even see the box. So ADHD people tend to be able to find creative solutions to problems, and research has suggested that a team with at least one ADHD person in it will tend to significantly outperform a team without one.
There are certain jobs that suit people with ADHD. The creative arts can be good. It has been said that ADHD is almost like a pre-requisite to be an entrepreneur. Sir Richard Branson has ADHD for example. Running a business doing something you enjoy takes care of the motivation, and also the dealing with the frustrations of working with a boss and co-workers.
People with ADHD thrive on challenges. Doing the same thing all day every day with no variation is a recipe for disaster. Pet projects are perfect. If an ADHD person is given their own problem to solve, they will solve it when they are allowed to do it themselves. Once they take ownership of a project that motivates them, it's a done deal.
We also thrive on crises. Every little thing in life is a crisis, so we are used to working effectively when it's all going to hell. We've been doing it all our lives. When others are panicking, an ADHD person will often enjoy the challenge and will get more fired up.