A big factor the rising diagnoses could simply be that with more mental health awareness, millennials seek out the help they need and get the diagnosis. It could be that with our fast paced environment of smart phones, social media, and that the economy is terrible for us with astronomical college costs could also play a factor in our health. Diet and exercise also matters as that could cause diabetes II if you don't get enough exercise or eat terrible food, which again could factor into your economic status.
I think we need to take a step back from things and focus on improving our health and realize that not everything trendy is good for us. We shouldn't eat out so much and learn how to cook our own food because it's not only tastier but much healthier. Sometimes we feel like we have no time to take care of ourselves or don't even have a primary care physician, but when we do take the time, it will be worth it.
May your futures be well and happy, millennials! I'm rooting for ya c: