I really doubt that Synaptol would help much. If you look at its ingredients, it is a shotgun approach with many, many different things. Fortunately, most of the amounts of the different ingredients are so small that I doubt that they could do anything helpful and in fact, some could be harmful in larger doses.
It has been advertised on this site for years (over my objections), and I have never seen a response from a user. Perhaps because it is so expensive.
It you want to try natural things to help.
The first thing would be to make sure that he is getting a good nights sleep. Apnea really increases hyperactivity.
Diet wise read this link -
http://www.medhelp.org/add-adhd/slideshows/9-Worst-Foods-for-ADD---Plus-1-That-Can-Help/20
For things that you can do around the house -
http://www.medhelp.org/add-adhd/slideshows/8-ADHD-Culprits-Lurking-in-Your-Home/21
Finally, the book I recommend the most is "The ADD/ ADHD Answer book," by Susan Ashley.
I would add that all studies have shown that (once you have tried the above), the most effective treatment is medication and behavioral modification training. The important part here is that medication is only half (if that) the answer.
Please post if you have any more questions.