I think that it's one of those things that are hard to prove on way or the other, it's difficult to assess if someones problems are a result of a set of circumstances or just chance, genetics, or a host of other things. Also setting scientific control groups is just about impossible.
But the anecdotal evidence is, to me anyway, very strong.
I have a very good friend who is now considered an expert in her field of adults with learning difficulties and dyslexia, and she is convinced that all traumas and abuses CAN ( but not in all cases ) lead to learning and concentration problems.
she has done several tests with me, and I have often been her guinea pig in tests, and because she also knows about my abuse and I'm open with her about all the therapy etc, she is confident that my abuse at worst led to my problems and at best made existing problems worse.
When I started at boarding school at 11yo I was a bright kid who did well in most subjects, never quite top of the class but close. By the time I was 12yo I was disruptive, and usually bottom of the class. I failed just about every exam I ever took and my apprenticeship. I lied my way into jobs and got by on my wits.
The only worthwhile qualification I have is in Counselling, which I got over the last few years. But that was with great efforts as I still don't have the ability to concentrate, and more importantly remember information in such a way that I can reproduce it for an exam. The Counselling course was assessed as we went along and we did a taped session at the end of it, so I didn't need to remember details of theories, but I could write about them in an informed way for my course work because I could read the books and do it 'fresh'. Surprisingly a lot of information sunk in that way, but not the sort an exam would ask for such as "Briefly outline a Humanist theory and say who are the most important humanists" - I couldn't do that, but get me talking about Maslow, and I know about his ( humanist ) theories. And I've just picked up a Counselling text book to write that example, that's how my lousy memory, poor attentivenes, and learning difficulties have affected me and still do.
Throw in dyscalculia - dyslexia with numbers - and it's no wonder my teachers gave up and branded me as being stupid. But now, as an adult who's got off my butt and done something for myself, I know that I'm not stupid. I just learn things in a different way, that's all......
Dave