There is a book that has a lot of information about this and other brain activity. I watched it on PBS one night and ordered the book the next day.
Dr Amen gives supplements and diet that may work. I will look up his suggestions in the book for you.
The book is “Change Your Brain Change Your Body” http://www.amenclinics.com/cybcyb/
Then Dr Wright has done some research on a supplement found in tomatoes, lithium. Not the prescription dosage but the supplement dosage. Also know to protect the brain if someone has a stroke.
http://www.tahomaclinic.com/lithium1.shtml
and I’m convinced that lithium is an anti-aging nutrient for human brains. And there are also some very strong reasons to believe that lithium therapy will slow the progression of serious degenerative mental problems, including Alzheimer’s disease, senile dementia, and Parkinson’s disease.
You would have to have any supplements cleared by the physician of course. Which may be your biggest battle ever.
Someone here mentions depression. Dr Amen also talks about that.
I don't buy this in general because of my personal experience. I knew someone who took lithium for manic depression for many years. It certainly did not prevent dementia in his case. (That is putting it mildly.) He had been an extremely intelligent person.