I have an opinion in this area.
I worked out a theory about trauma and ADHD. It is that they cohabitate (or operate in) the same area. I suspect they each serve to stunt learning by negatively impacting the reward mechanism that cements learning.
The above notions flow from my considerations of my own abuse, neglect and cognizance issues. I have some confidence that they explain much of my long term learning issues.
Explanation
I have always experienced ADHD as a brain fog that obscures and distorts the details involved in natural learning. During childhood, I required a methodical and rigorous study of the same mundane details that my peers absorbed trivially. When my peers felt reinforcing joy in learning, I felt exhaustion and frustration as I raced to catch up to them. Eventually I could mimic their understanding - but by then they had grown further.
During the catching up, I learned a lot of details and had moments where my reward would kick in. But it was for trivialities - for things I achieved that most children learn w/o notice. My positive expressions here could be confusing and discomforting to peers and others and I learned to suppress those feelings.
Regarding abuse and neglect. They pushed my reward system out, much more directly. I learned to bury responsive joy when I received abuse in response. I abandoned responsive joy when it lead to nothing (instead of needed, nurturing reinforcement).
I will note here that children do not do well when given adult-sized burdens of internalizing emotional systems that, in healthy environments, are openly and freely expressed. Emotional misfires are the predictable result of poor containment.
By adolescence, my reward system was reliably - 1) not there when I needed it and 2) often overly-present at unhelpful times. I mistrusted of one of the best parts of being human.
For me, abuse and ADHD were two persistent vectors toward this one transformative outcome, my broken reward system.
For an epilogue, Adderall has been a late stage, happy-ish outcome to this story. Every day, I reliably get a period of trivially-triggered reward. Into this, I can feed experiences and receive learning and understanding. I often say it is the difference between me receiving a lesson and learning it.
This is much better than no payout at all. However, I am distressed by the many interests (DEA,pols) who regularly attack my meds and want to take this away from me.