I think Haidt's assertion that social media is to blame for the rise in teen mental illness is likely indirectly true, but from what I've observed personally even kids that don't frequently use social networking apps still seem to have much higher rates of mental illness than I recall when I was younger.
My bet is that social media use itself isn't that harmful (I understand this is a radical position), and that it's actually far more related to the pathologisation of normal emotional states as mental illness which social media has exacerbated.
In recent years I've occasionally spoken about my own negative thoughts and struggles with depression, and almost without fail someone will try to encourage me to seek help, and more worryingly they will often recommend medicating. This has even been true when I've visited doctors in recent years where a couple of times now I've been asked if I'd like help for depression and anxiety after making passing comments.
Furthermore, in recent years whenever I have tried to suggest that someone probably isn't mentally ill, but just a little more anxious / depressive than the average person I've been attacked and told I'm causing harm by questioning their need to be on medication.
I'm writing this because just today an 8 year old boy in my family was put on ADHD medication. The school told his mum that he was struggling to remain quiet in class and has been distracting children at his table, so recommended he see a doctor. The mum took him to the doctor and within a single meeting the boy was put on ADHD medication. Notably, this mum has 3 children and all 3 are now on medication (the other 2 are being treated with anxiety and depression, both at a similar age).
The truth is I'm not convinced any of these children even have mental illnesses. I'm not a doctor, but they seem extremely similar to me and many of my friends growing up. But when I was growing up I didn't know anyone on medication for anxiety or depression – certainly not any children.
The only evidence good evidence to suggest that there's some difference between my generation and teens today seems to be the suicide rate. But I think we need to be careful here also. Something that has concerned me is how powerful some of these drugs we're prescribing children are. I don't know how common this is on SSRIs, but one boy in my family seems to have lost his ability to feel normal emotions after being prescribed what I understand to be a high dose of SSRIs. Shortly after starting medication he started to become increasingly physically violent and started to self-harm. Absurdly in light of this when taken back to the doctor they decided increase his SSRI dose because the kid said that he was still feeling unhappy. When I spoke to him to try to understand why he was being violent his answer was basically that he just didn't care, which struck me as strange to hear from someone who was if anything an overly emotional and overly affectionate boy.
I'm bringing this up because teen suicide trends also seem to track very well with the increased prescription of SSRIs like Sertraline to children, and my understanding is that there is good evidence that these drugs can increase risk of suicide. So with more children taking these drugs we should assume that one of the outcomes of this will be increased teen suicide.
Finally, I'd also be interested in better understanding the role loneliness has on children and whether this is more likely to be part of the explanation. Children today are less likely to play outside with friends, and declining birth rates mean children also less likely to have siblings and cousins of a similar age and gender to play with. Even if they're not on social media children today are far more likely to stay at home watching YouTube or playing XBox on their own, which probably doesn't help with their mental health and their ability to deal with the real world and the social conflicts it brings their way.
It would be silly of me to suggest social media plays no role of course, but my guess is that the role it plays is more indirect and more related to the over-diagnosis and hyperawareness of mental illness. And also in its contribution to children spending too much time inside on their own.
That's just my thoughts on this anyway. I'm obviously not a NYU professor who's studied this in great detail so I'm probably talking nonsense. All I can say is that in my anecdotal experience doesn't really align with this idea that social media is causing these problems. worry those like Haidt who are quick blame social media are primarily getting attention not because they're pointing to the correct cause, but because blaming social media for all societal problems is in fashion right now, while people like me suggest that we may be over-diagnosing mental illness in children attracts a lot of negativity in a world that increasingly wants to destigmatise mental illness.