In some countries it's almost impossible (I don't have any direct experience but I've heard tale that in e.g. aus/nz, east asia, south asia, etc people give up before getting diagnosed often), and my understanding is that in Europe it's virtually unheard of to have an adult diagnosis.

In the US, at least, it ranges from difficult to straightforward, but that's not true everywhere

> ... my understanding is that in Europe it's virtually unheard of to have an adult diagnosis.

Can't speak for the whole of the continent but UK here and I got my ADHD diagnosis a few years shy of 50 years old. Wasn't tricky at all, just a long-ish (8 month) wait for a non-private diagnosis (not full NHS but via an outsourced provider via Right-To-Choose).

When going through the DSM-5 questions (during an ~80 minute interview) I was asked to give examples from both current life experience and from childhood, and that was enough.

Europe here. I have several friends that got diagnosed with ADHD as adults.

If you try to do it through the public system it's very difficult to even get an appointment because there's months long waiting lists. Basically if you have a job and function somewhat OK in normal life you won't be diagnosed in the public system. If you do get through it can be a long process where they want to interview your parents etc to determine if you had symptoms as a child. But you can also get a diagnosis through private practitioners and some of them function almost like diagnosis mills. A couple of video interviews and tests and you are done.

In NZ it's easy, and some GPs can do it as of earlier this year.