Dear Dr. Beth, I just turned 70 recently and I have noticed that I am not as sharp in my thinking as I used to be.  I used to be able to juggle a number of activities and projects at the same time, remembered appointments and information I read, and just generally thought and reacted to things more quickly.  I don’t know if what I am experiencing is due to normal aging or due to a real problem developing in my brain.  How do I find out what is going on and whether I can do something about it?