I'm diagnosed with ADHD, generalized anxiety, and have some PTSD junk. I'll go ahead and give the long answer to the question.
I've found diapers are something that has helped me cope in everyday life very well actually, and I've fallen into the habit of wearing them consistently for almost a year now. It's something that takes the edge off and acts as an emotional safety net. While it doesn't stop meltdowns, executive function paralysis, or any of the other stuff that comes along with the conditions, I've been way better at recovering when those things happen, and they impact my life far less than they used to. Diapers give me the emotional support I need to be proactive and reach out for help or communicate when things go wrong.
I've gone from college part-time with a job to full-time school with work and making the dean's list. Which, this is coming from someone who struggled to reach a 3.0 GPA in high school, and almost failed multiple classes. I still take medication, but having something I can wear that helps me to the degree it does has honestly changed my life for the better. I enjoy the routine/structure and comfort that I otherwise often struggle to give to or allow myself. Self-acceptance is rough sometimes, but I've always been far better for it.
I'd probably say wearing correlates with my mental health, but I know it isn't the cause, at least not exactly. (My past isn't something I normally share, but I'll put it in here since it's relevant) In my case, I was pretty consistently abused by teachers verbally and physically between the ages of 4-6. It was in large part due to undiagnosed conditions that made me act out in class because I didn't know how to communicate my feelings, remember things, make eye contact, handle overstim, or sit still and pay attention. To most, it just looked like I was being defiant when in reality I couldn't help it, nobody was helping, and I couldn't understand what was going on with me.
It was also the same time my interest in regression started up, after our family home caught fire and we had to move while it was being fixed. The abuse did get better once my mom stepped in at school, but being neurodivergent has always been something that has caused a lot of issues interacting with the world, not to mention the problems of being medicated from a very young age and always being perceived as having something wrong with me my whole childhood, that my existence was always wrong somehow. Most of the friends I've spoken with also talk about their interests starting around traumatic or stressful times in their lives and things stuck around since. It's always interesting to hear about other people's experiences. I hope sharing this can let others know they're not alone if they're facing anything similar.