IMO, you should definitely address any low scores, particularly if you have been treated or were treated by a physician or mental health practitioner during that time period. While I have never personally experienced depression, I did get some W's during my sophomore year due to a some serious GI issues that required surgery. Remember, they don't want to hear excuses. They want to hear how you identified a problem, developed a solution, and implemented that solution. If you have since improved on those D's and F's, highlight it. "I bounced back from my depression and improved all of my low grades". Hope that helps.