I absolutely see the correlation myself, but which way does causation go?

I can make a case for how engaging with short form video can be bad for mental health. I certainly saw evidence of that first hand in one of my children who engaged heavily in TikTok.

But I can also make a case for how poor mental health makes it hard to resist engaging with short term video. For example I have a child who is currently struggling with being suicidal. I find that when she's in particularly bad shape, I find it much hard to resist getting sucked into YouTube shorts. But when she's in good shape, I have no such problem.

The combination of the two seems to lead to a doom loop that some people get sucked into. But how can anyone separate the relative importance of the two directions in which causation could run?