If it is a significant problem to you, it really would be best to go to a professional and get their opinion and recommendations.

I do that too btw. I keep reading things over because I'm afraid that I might have missed something, or sometimes because I realize after I get all the way to the end of a paragraph or a page that I don't have a clue what I just read. My mind was someplace else and I didn't take it in. There are lots of possible reasons for this, and I'm not even sure which of my dx this is most related to. Could be any of them.

It could be dissociative, in fact I'm sure that in my case it is quite often. Part of me was here reading, but the rest was off inside my head someplace else. Dissociative symptoms might be related to dissociative disorders, PTSD, BPD, etc. Dissociation is also a natural ability that everyone has, which isn't abnormal at all unless it is a problem for you.

It could be ADHD. Lack of ability to concentrate. It's also really hard to concentrate sometimes if you have depression.

If your need to re-read things is more compulsive (you paid attention when you were reading but have to go back anyway because the thought nags you and won't go away), then it could be OCD or Obsessive-Compulsive Personality Disorder. What would happen if you didn't go back and re-read? If your thoughts tell you that you have to do this to prevent something bad from happening, then OCD is a good bet. BTW, it is a common myth that people with OCD are always neat and organized. Many are not. It is a big ordeal to go through some of the rituals, and takes lots of time. Some people with OCD spend nearly all their time engaged in compulsive behaviors and don't have time left for cleaning up or other things. And they don't all have the same obsessions and compulsions either. Nothing says that it has to be about being clean and organized. OCPD is more based on having rigid ways of doing things, and is more about the inflexibility and need to stick to a certain routine, and being upset about having to do anything differently.

Having to read things over, and generally doing things slowly, has kept me back in school because I didn't finish timed tests. Doing my homework and studying take forever. I am a perfectionist. Sometimes I can't read my email or go into a forum here because I know I won't have enough time to finish it all. It takes me forever to go shopping too. I have to go back through the aisles and see if there is anything that I needed that I hadn't remembered. Send me to the store and I'll be back in 2 or 3 hours.

Rap