As a parent of 2 teen sons and 1 tween son, I can appreciate the need for space from the froo froo feelings discussions. I would say that as a teen, I myself battled what I would consider anxiety/depression by today's standards but that was then, this is now.
My best advice is to find ways of keeping your teens engaged about the things that interest them. Who are their favorite youtubers? What's going on in the world of hulu/netflix for shows? Do they like stand up comics? What's going on in their group snap chats? Instagram follows?
Keep them focused on their joys.
Oh...also...try to utilize effective communication techniques the best you can. In ways that express...less talking to me like that and more like this. Not easy but possible.
Also...disclaimer...I've had anxieties in full form. Teen boys tend to unleash anger as a main symptom of depression. There's been a hidden adhd dx with loads of defiant bordering odd going on over the years. There's been crisis counselors, therapists-in office and in home, school refusal destroyed furniture and other household items. Broken glass...you name it.
I'd also highly recommend building a good support system.