Question about nonverbal thoughts

I do not have Aspergers. I have ADHD-C, and I believe you may be able to point me in the right directions. I was searching the phrase "nonverbal thoughts" in Reddit, and this subreddit popped up as a related subreddit with lots of search results.

1. Is nonverbal thinking associated with ASD?

2. I would like to find good books, articles, blogs, etc., about verbal and nonverbal thoughts. (I would like to understand how it is like to have primarily verbal thought processes, and incorporate them if possible, because I see some benefits of having thoughts in language.)

3. Any input would be appreciated.

I have always assumed that nonverbal thoughts were the norm, and assumed that the phrases like "internal dialogue" and "self talk" were metaphors.

I've been googling around about this for a while, and finally asked to my psychiatrist to confirm that verbal thoughts were the norm. I trust her, and she is very knowledgeable, so I stopped questioning if the statement was true, but I still have hard time internalizing it. I guess it will take some time.

It seems that nonverbal thoughts are associated with ASD. There is a book written by an autistic person about her life with autism, and its title is "Thinking in Pictures". This book wouldn't have this title if the majority of neurotypicals shared her way of thinking... right? But it is also very difficult to try to imagine any ways of thinking other than the one the book describes. Maybe it would be like having a constant imaginary conversation with myself. I am able to have imaginary conversations in my head, and I find the imaginary conversations with my psychologist and psychiatrist quite helpful.

After I learn enough about verbal thoughts, I will be able to use it to improve my current coping system for ADHD, hopefully.