Definetely I have had a very hard time concentrating due to depression.
I need to focus on things that I used to do without thinking at work and in my everyday life. I find it very hard to deal with this and more.
Even driving which I used to love is a chore and I dont venture very far these days.
I also have lost interest in almost everything.
I do beleive they are symptoms of depression, anyways in my case they are, my doctor also wrote them on my paper for leave of absence!