If someone is sad or anxious they might be in a depressed mood
Yes its a new age problem thats growing bigger every day, are you anxious sometimes?
No not really. I've known people with Borderline personality disorder though. 
What is that? i havent heard of it
It's a long-term pattern of unstable behaviors, loss of identity, and promiscuity 
Omg its really bad, now i know, what can you tell me about depression, i think i feel depressed sometimes 
It's mainly marked by low moods and aversion to activity