This is something I've been thinking about for a while now.
I'm in my early 40s, and was diagnosed with ADD ( inattentive ADHD it's called now? ) when I was living in the states at age 14, so nearly 30 years ago.
At the time of my diagnosis, it seemed like a "trend" to me; kids were being prescribed Ritalin at exponential rates, it was all over the news. Stubborn soul that I am, I resisted taking any meds, and I also laughed off the diagnosis and didn't tell anyone or even think about it much, for years.
About 10 years ago I came across an article about how women present with ADHD ( and how the default of boys and mens behaviours meant that girls and women were missed in diagnosis ) and it felt like someone had spied on my life and written an article just about me and my behaviour.
It was a wakeup call. I now realise that my doctor in the states did me a favour and was probably a bit revolutionary at the time. I wish I'd tried the Ritalin, just to see what help I could have gained from it.
As it stands now, I function well and apart from anxiety flares, I feel fine day to day. I struggle with RSD, I have frantic, high achieving/paced days followed by lethargic ones, but on the whole I have learned to give myself space, and time, and have built strategies into my life that help me.
It's still very easy for me to turn inward and blame myself for being the worst person in the world when I make silly mistakes, but I am kinder to myself than I was, when I didn't acknowledge my diagnosis.
So that's what diagnosis has given me. And it wasn't a trend, it was an accurate description of how my brain works.
In terms of tiktoks etc, anyone consuming media that's bitesized to that extent needs to be aware that you can only simplify complex information so much before it gets distorted beyond all recognition. That's my concern, as well as the social contagion aspect. Don't use social media to self diagnose. If something resonates, great, but take the conversation to a professional, and don't rely on hours of personal testimony videos as a diagnostic tool. They aren't!