I can say that for me, meditation changed my life in just a few months from constant underlying anxiety that I was hardly aware of, or more correctly, had become so accustomed to that I didn't know something was wrong, to having worries, but being able to address them.

Here's a study that I'll need my brain map for, but it's still interesting.

http://www.medpagetoday.com/PrimaryCare ... 01&spc=224