@ZipLine-- Dendrite growth affects our memory and also our learning potential. So dendrites do in a way affect our intelligence.
The best way to grow dendrites is to actually do something repeatedly. When we do something just once or twice, dendrites actually don't grow. They grow depending on the potential of that information becoming useful in the future. So if when we repeat activities, just as we do while playing chess or a musical instrument, dendrites grow because they know that this information will be handy later on.
So someone who has a lot of brain activity and engage in activities for long term should grow a lot of dendrites.