A healthy brain just keeps getting better with age. That is the surprising discovery of Ernst Pöppel, a brain researcher in Munich. Vocabulary, verbal memory and spacial and associative reasoning reach peak performance between the ages of 40 and 56. Ernst Pöppel says young and old brains show very little difference.
So there's no reason they can't function optimally a whole life long - provided they're kept in shape like muscles. They can even grow new brain cells. The neuro-networks and transmitters, on the other hand, can get a bit rusty with age.