A potential issue with music study is that only a certain fraction of kids who are given music lessons actually thrive at it. Many people remember being forced to take lessons and hating it. Others failed on multiple attempts until it finally "took."

So for this reason, I'm not sure that music training is a single "thing" that can be analyzed without looking into how each person experienced it.

Another possible study is to measure successful musical training by whether someone is actually a musician or not.