Teens living with a depressed parent need information and support. The inclination of most people living with someone who is depressed is to take on responsibility for the ill parent and other family members.
Life is difficult for anyone living with a depressed parent. The daily home life is complex - with little consistency, irregular habits, plans made at the last minute, little consideration for each person's wishes or desires, and there is usually a huge decrease in communication. The depressed parent withdraws from the family and the teens are left to manage on their own, creating feelings of loneliness.
Teens are not likely to realize how much their life has changed, or how serious the depression is and need adults who see the changes to bring them to the attention of the family, medical and emotional professionals. Even if the depression lifts for a period, everyone in the family will likely be anxious about when it will returns.
I believe that all health care professionals are ethically responsible to help teens avoid the responsibility and loneliness associated with living with a depressed parent. As mentioned in a previous post, there are also many resources for those parents who are willing to admit the depression, as well.