About 6 months ago I noticed that my memory started to decline very noticeably. I'm not forgetful, I actually have really good memory. The problem is that I am very frequently experiencing my mind going blank or losing my train of thought. I will be working on something and all of a sudden I can't remember what I was doing or what I had to do next. If I just wait a couple minutes or so, the thoughts will just come right back. So if I was writing a paper for instance and I had to go to the web to look something up, once I get to the web browser I can't remember what I was needed to search for or even what I was doing before. But then if I just sit there for a few minutes, it all comes back to me. It's very strange because I'm not getting forgetful, I'm just blanking out all the time. I know this happens to everyone now and then, but it's happening constantly throughout the day now. I have to make lists for myself to keep track of what I'm doing. Anyone ever heard of this? What could be causing it?