At what age does the brain fully mature?

[yammi]

When you are younger than that, it is hard to believe that figure of brain maturity around the age of 21. You KNOW that you feel mature at 16 and definitely 21. Despite that the figure does seem to be true. Looking back, you will not believe how naive you were, how wrong on some things and how you really didn't have the same perspective on life you have as you get older. Of course it continues to change but that period up to the age of about 25 is a real helter-skelter ride of growth and reorganisation.