anxiety
"While I found this medication to be effective for anxiety, the concentration & memory loss were terrible and almost cost me my job.  

I didn't really notice anything was wrong until I started my new job.  Training was a nightmare.  I couldn't focus long enough to learn anything new!
  
I was reading a short list of keywords and by the time I got to #3 I couldn't remember #1.  I couldn't pay attention long enough to read a book, or even a short article.  I couldn't remember people's names.  I had to write everything down.  I couldn't focus on anything anyone was telling me, I would just pretend like I understood.  

Luckily I noticed something was wrong and stopped taking it about 2 months ago.  My memory and ability to focus have improved."