I have some experience with this topic. (Spoiler alert: I don't think it's really a mental health crisis.)

I left my mission after 6 months because I realized it was a scam. The last 3 months were spent in/out of the offices of LDS psychiatrists & counselors, who were trying desperately to find a medical explanation for me having list my testimony (chronic depression runs in my family, and my parents disclosed this to the mission pres). Like most of us on this sub, I really wanted it to be true so I obediently went along.

Here's a line of questioning that I remember quite clearly:
Dr. - "Elder JustCallMeHeber, are you having trouble falling asleep or staying sleeping?" Me - "No, not really." Dr. - "What about weight gain, or anything different in your diet?"
Me - "No, I don't think so." Dr. - "Tell me how you feel about yourself?" Me - "Well, I have a hard time reconciling my actions with my beliefs right now. On one hand, I'm lying to these people when I tell them something is true but I'm pretty sure it isn't. On the other hand I want it to be true, and my numbers are pretty good, and I'm kind of scared about the implications of it not being true, and I don't know how long I'm supposed to keep this up before 'enough is enough,' ya know?" Dr. - "Elder JustCallMeHeber, I think you're experiencing depression and it's getting in the way of you feeling the Holy Ghost."

So they sent me home with an "honorable" release for mental health reasons. It was a sham diagnosis and I haven't really thought about it much since then (2001) because I never really cared what their explanation was.

It's Mormon psychiatrists diagnosing these "mental health" issues before sending these kids home, so take that 15% number with a grain of salt.