Why doesn't he take medication?  It may help.  If you don't want him to take medication you can try a hollistic aproach to his ADHD.  I personally haven't tried that approach, but, have heard it can work.  It's a lot of work though:  chemical free cleansers, chemical free food, etc.  I have a chat forum (support group) for parents of special needs children and ADHD is one of the topics I talk about.  It's a new support group, but, you're welcome to check it out and see if it's any help for you.  www.snparentalsupport.proboards.com

Novelty is one of the keys for maintaining attention.  Try placing a colored placemat under his study pages to draw his attention to them.  Allow him to do his work standing up, sitting on the floor, sitting on a large ball (except for writing!).  Reading can be done while on his stomach on the floor.  Wrap the front legs of his chair with a band of exercise band (can get a Target).  He can put his legs behind the band and push against the band to help him focus better.  Think deep pressure (exercise band, chair push ups), sucking (straws, hard candy), and chewing (gum, jerky) for helping with attention.