The problem with most therapy clients - and medical patients - is that they incessantly complain about what they don't want and don't understand why they can't get rid of it.
Essentially, they are feeding their weeds and complaining about it at the same time. Once I point this out to my highly intelligent patients and clients - to include surgeons, lawyers, and dump truck drivers - they give me a puzzled look and say that that just doesn't make sense.
I agree.

The delay in the development of an internal language causes children with ADHD-HI to have difficulty with thought processing and also causes these children to have more negative thoughts. I believe that children with Predominantly Inattentive ADHD can also have problems with internal language but the problem is not that the language is under developed and more that the language can be over developed and negative.
This is what Barkley says about internal language with regards to ADHD-HI: