A child's life depends on his mother's nutritional state the first 3 months in the womb, when this was lacking the child will struggle for a lifetime. What was consumed by age 5 sets the brain and when lacking, all will lack.
In the USA the lack of organic iodine has been a permanent problem and the fast food and dentist make sure the kids do not have a chance.
I suggest removal of all POP and commerical drinks and make your own fruit drinks and teas with your own home made distilled water. Then supplement with a good organic mineral source and make sure he has all he needs.
He does not need TV or radio. Get him a mini trampoline and exercise daily. Go to sleep at 8-10 and eat only live foods.
These are just a few suggestions.
The lack of iron and iodine are the basic problems that can be worked upon. The lack of iodine in the woumb and to age 5 slows the brain wayyyyyyyyyyyy down.