https://www.cdc.gov/nchs/data/databriefs/db471.pdf
Not proof that social media is behind it of course.
Suicide and emergency room visits for suicide attempts among teenagers are also up, and also on exactly the same post-2010ish timeline.
It causes mental illness like depression and also stunts social development.
Which necessarily follows because the closer you look the fewer people are "normal". In fact I'd go so far as to posit that everyone is aberrant, to nobody's surprise.
And of course this is all derivated from a basis of largely qualitative soft-science which had ought be treated as an art than it is a science, however there are pressures which force both practitioners and researchers to justify it as a science.
I'm sure there's some "law of self-awareness" as well. The closest analogy I have is the January Effect which describes an even in the market, a pattern of sell-off in the later year to mark a loss, and subsequent repurchase in January. Upon this pattern being disclosed, the market adapted strategies to exploit it which ultimately resulted in a complete silencing of the effect. In a sense more applicable to this, being diagnosed with some mental illness can also be leveraged to gain favor, I mean I can get a prescription for pharmaceutical grade amphetamines for fidgeting for instance; or excuse my bad behavior with some other diagnosis.
My position is that it's all very unclear. I'm lazy and don't care to dig it up but there was a study from the UK that observed the measurable effects from school based, non-individual interventions and it found their effects to be significantly detrimental for some students - to the extent that they negated the aggregate benefits - which I think supports this position because treatment can exacerbate things. And that's without mentioning pharmacological interventions which are... Interesting.
It really does feel like I was bred in a lab to exist as the counterexample for all this. I was diagnosed with ADHD in middle school and my parents thought exactly as you did and refused treatment. For a long time I held this as a point of pride and thought of my parents as saving me from those cruel teachers that just wanted to keep me down, any why would I question them? I have no other frame of reference and was marked "different" by my teachers and other kids so all of my struggles were just framed in terms of that. And so it went with my anxiety and depression, I didn't have an illness, I was a worrier that just needed to calm down. I didn't have depression I was lazy, angsty, and logical -- that's why I didn't get out of bed all day, thought everything sucked and existence was pain, and so numb I could give Spock a run for his money.
Fast forward to college where I was getting my annual checkup and flu shot and I got my first ever mental health questionnaire. I answered honestly because at the time I genuinely thought that my experience wasn't unusual -- "Doesn't everyone think about killing themselves all the time?" I got referred to a therapist and eventually a psychiatrist for confirmation (because teaching hospital) who both didn't even take an hour to be clock me with all three. I got put on an antidepressant, an anti-anxiety, and a stimulant over the course of about a year and a half and I felt something and then cried for the first time since sixth grade, realized what not having anxiety feels like, and what life is like when you're not constantly in pain from under-stimulation.
I just can't bring myself to think it's all quack science when I was so thoroughly dressed down by these two guys so fast and who took a little less than two years to get them all sorted. It was surreal when the psychiatrist just described my whole life experience without even missing a beat. Life changing undersells it so much and it came out of literally nowhere for me.
This is definitely a thing, it first started getting obvious on Tiktok with Tourette's.
So they didn't have Tourette's and they weren't faking it, but a seriously cool third thing. Monkey see monkey do is a powerful phenomenon. We just treat it as normal when it happens as part of socialization.