I’d never say it causes them. But if someone with mental health issues is using the internet, they may be especially vulnerable to lots of negative online influences.

It can cause depression to get worse because it is addicting and it's hard to find other hobbies while you're staring at your phone waiting for someone online to chat with you.

It depends how you use the internet...

If someone has a problem...certainly indulging that problem and feeding it with misinformation, etc can make it worse right? On the other hand it’s better if someone only indulges it online vs real life....it’s the paradox!

Being online can open oneself up to a lot of ugly and dark aspects of humanity. If one is feeling especially vulnerable. That may not be a terribly great thing.

It enables and enhances preexisting conditions, as you said

It definitely can make things worse for some.

It can hurt and it can help. Depends where you go 😐

it brings them out.