Study says children who are encouraged to write have sharper brains than those who type more. For adults, typing may be a fast and efficient alternative to longhand, but that very efficiency may diminish our ability to process new information
It doesn't matter what your age is. Any age is suitable for adopting a healthy signature. I find the 16 to 25 age group ideal for a signature correction, primarily because this is the time when a person decides to adopt a particular signature style.