my older brother was diagnosed as well around 3rd grade, and my parents DID listen to doctors who put him on Ritalin..
it most certainly didn't help..and, if anything, pushed him further towards alienation and dysfunction...my mom still questions about the decision to have drugged him..it's quite sad
he continued to struggle all the way thru school, and now at 41, still struggles thru life.
I believe there is definitely something to "chemical-inbalances" such as ADD.
I should say, for all the issues that my ADD has caused me over the years (and I DO have all the classic symptoms), I still managed to get through high school and graduate with good grades, at least the year I graduated. And then went on to University where I dropped out in the second year on my first go at it. 3 years later I was back again, got my degree (Computer science), and now hold down a good job as a software tester. So, it's not as though chemistry is destiny, at least in milder cases like mine.
You and he might want to look into candidiasis -- excessive yeast in the gut. "The Yeast Connection" is a good book to start with. The 1940's heralded antibiotics, and they kill good bacteria in the gut, allowing yeast to overpopulate, generate toxins, and perforate the intestinal lining. I'll wager he got antibiotics as a child, gets recurring antibiotic treatments now, and eats a lot of sweet and processed food.