Adult ADHD seems quite controversial. do you screen for them? once you screen for them and it almost leads to false positives. does it not leads to excessive medications? there are no clear answers.
but clearly there are clinical cases. for example, a medical doctor who made it through age 40 and is successful in his career. smarts must have allowed this doctor to adapt and get to this stage. But for the first time after being prescribed ritalin, is able to listen to lectures 3 to 4 minutes straight. it is clearly a night and day difference for the doctor. but you say, he made it to age 40 and is a doctor. why medicate? he wants to medicate because he realized his potential could have been much higher. the positive effects on concentration is night and day different. Likely this doctor will have more control over his focusing and do a better job in his life and career. (still, not a miracle difference in his world.)
are children overly medicated for ADHD? i am sure there are many children who should not be medicated. this question is away too difficult so i will just put it in the too hard folder. Sorry. that is how life goes, folks.
Should every one be screened for ADHD? i do not think this is a priority given that depression, bipolar disorder and schizophrenia needs to be screened more and the consequences of these illness and many other brain disorders are more detrimental. however, for the positive consequences of a person with ADHD, screening may be helpful as some people with ADHD do not know they have ADHD and the overvalued ideas told to them is that they are lazy, depressed or rebellious. may not be laziness but lack of interest (with interest, they do hyper-focus). may not be depression but real failures in certain settings not good for them. may not be rebellion but more that they are poor in listening and is unable to retain what they could not hear.
Ways to concentrate: more quiet, less outside environmental distractions, letting go of the past, have an hour limit to spend on the now and not worry about the future, consign to oblivion of past experiences so you can focus on the now, have a beginners mind and do not assume anything, turn every page as Robert Caro writes in "work," moderate caffeine use or dopamine increasing so more able to turn to inner thoughts, as opposed to outside noises. I believe outside phenomenons such as people and caring about what other people think, or even the great ability to empathise has an adverse effect to focus. i believe empathy, i.e., putting self in other's shoes as a good therapist can, is like getting a macro view in google maps. while focus is like zooming in on the map screens to see the details of logics and reasoning. also this zooming in is needed to create things that are good, truthful and just works. Focus is perhaps a tiny microscope zoomed in so that it is impartial, not seeing the self or the empathised people, but a concentration that is detailed, useless and not trying to achieve or please and in the now and seeing the details with it is how it is. This concentration may be best summed up with turning every page and practicing attentive oblivion with a beginner's mind.