I've been very focussed on hair restoration since coming out to myself (before that, really) and I have hair replacement surgery next week. But over the past 4 years, I've regrown quite a bit of hair. I'd been using topical minoxidil for many years, but added finasteride 4 years ago in order to suppress the DHT. That, along with herbals, caused budding and a bit of breast development, which encouraged me to pursue physical transition.
We know that suppressing DHT is critical to preventing hair loss, and will also allow hairs to regrow if they haven't been gone for two long. Finasteride and dutasteride are two common medications which are used for this. DHT is a "stronger" form of testosterone, so suppressing testosterone will reduce or eliminate the need to suppress DHT. Basically: no T=no DHT.
I've read several studies that state that higher estrogen levels promote scalp hair regrowth. Since starting HRT, I've regrown even more hair.
There are other "treatments", such is microneedling the scalp, laser scalp therapy, and hair regrowth compounds. The effectiveness of these treatments is a matter of debate, but most agree that they don't hurt.
But there's one thing that recently occurred to me, which I feel I need to share with others:
When I became aware of the fact that my hair was thinning, I became very fearful of doing anything that I thought would make it worse. I was afraid to wear hats. Afraid to scrub my scalp too vigorously when washing my hair. Even afraid of brushing it - for many years, I've just run my fingers through my hair to set it in place after applying minoxidil.
The idea was that any agitation would hasten the loss of my hair. I believe this to have been a major mistake on my part. Hairs fall out because of atrophy of the root. Minoxidil increases blood flow to the follicles, which helps prevent this, and can encourage some regrowth. Never touching one's scalp doesn't exactly promote bloodflow.
Because I always had thick, curly hair, I favored those stiff styling brushes that have relatively few bristles, with a plastic ball on the end of each bristle. If you look at the description for those brushes, most are described as "scalp massage" or "scalp and hair care" brushes.
I've been doing it all wrong. Now, I brush my hair a lot. I feel a bit like Rapunzel or Marsha Brady while doing it, but the result is that my scalp gets a bit red and tingly. Doing it this way gets the blood flowing and bloodflow is GOOD. And you know what? I look down in the sink and there aren't a bunch of hairs there, as I feared there would be.
Something to think about.