How old are you? What is your highest level of education? What were your grades like? What’s your job?
What impact does the “in-ability to think” have on your life?
I once told my doctor that I thought I had a bad memory. He asked what grades I was getting and when I said A’s, he said don’t worry about it, you are fine. If you are considering reading Ulysses, a notably challenging book, I think you probably have an above average ability to think.
What did the neurologist say exactly? I don’t think inability to think is a medical diagnosis.