I have a very hard time concentrating when depressed because I feel like there is a heavy fog in my head. It doesn't hurt but it does seem to affect all my senses as well. Nothing taste good or smells good, the world seems dull, colors seem muted and even seeing seems to be difficult because it feels like my head is full of smoke or fog and it is difficult to see out.

I also have migraine headaches but what I described above is totally different. I can't concentrate when I have those either but it is because it is painful.