I have PTSD w/ Secondary Psychosis, ADHD, TBI and SZPD. As a kid I was dxed with inhibited RAD (now just RAD in the DSM V). So I have a ton of severe, extreme, dramatic, etc symptoms as a result of all of this. PTSD alone is not capable of causing my symptoms, so I was diagnosed with other things. But PTSD, TBI, SZPD and RAD all have a causative agent rooted in environment - specifically, trauma. (This doesn't need to be interpersonal trauma, but RAD and SZPD in particular are linked to this.)
BPD as well has a pretty solid swathe of evidence indicating it has origins in environment, as well as genetics. My SZPD is both environmentally and genetically based. My whole family is rife with schizophrenia, autism, and personality disorders all. So it makes sense that with my environment being as extreme was it was growing up, I ended up with a diagnosis that is essentially a mixture of all of the above.
For me, SZPD/ADHD symptoms are the most disabling. Because my attention doesn't focus correctly, and because my brain lacks dopamine, it causes me to enter long periods of pseudo-catatonia where I'm unable to even move or speak. And because I have no motivation or goal-seeking behavior, I don't put any effort into overcoming that, since lacking the ability to extend effort for long periods of time is a defining feature of SZPD related to the negative symptomology of schizophrenia.
(And I was dxed with SZPD and not schizophrenia or schizotypal because my psychotic features are relative to stressors/trauma, and I lack paranoia or "magical thinking" or verbal incoherency/word salad etc, otherwise. It happens during psychosis, but those are time-limited events that tend to crop up in response to being stressed, lacking sleep, or having a PTSD trigger - and usually it is related to trauma and things I have actually experienced, I just lose touch with reality.)
My motivation, goal-seeking behavior, etc is almost nonexistent. I go months without speaking to other people aside from my mom. If I had my way, I'd sit in a room by myself and do nothing for the next 20 years. But on the flip side, ADHD can be a boon, because sometimes my attention will randomly and miraculously latch onto something that enables me to overcome the SZPD anhedonia - such as my pursuit of developing a videogame all of a sudden. That'll last for as long as it lasts, until my brain wrings out every last bit of dopamine from it, then I will probably be inert once more.
It's a challenge to treat the ADHD because stimulant medications are extremely triggering for me. So I use things like kratom and DXM and Wellbutrin to try and manage it. It's about a 'meh' on the 'eh' scale, but it's not nothing. It does seem to make things in my environment interesting enough for me to pay attention to them, even though my attentional orientation is still c'est tragique.
And, regrettably, I've been misdiagnosed several times. Autistic, BPD, bipolar, DDNOS, etc. Because ADHD and PTSD cause my SZPD symptoms to diverge from the normal presentation. I've been on this forum for a long time, so people may even remember when I just assumed I was autistic (it's actually in my introduction) as well as DDNOS. I even have experiences where I mistook my own symptoms as those of autism and would say "well I have autism, and I'm not like XYZ, so it can't be related to autism."
Or DDNOS, or whatever.