Mike D.

There are several mental-health communities. A few I can think of are /bipolar and /ocd.

the user feed is just made up of posts from people you follow in chrono order.

You can also follow hashtags, block hashtags, and block words/phrases.

The Local Timeline shows posts from everyone on your instance. The Federated Timeline is a fire hose. It shows all posts in chronological order (as received by your instance).