The following poem is from a collection of 41 written by me to try describing Huntington’s Disease (HD).

"Perseveration" is described as "the tendency of an idea, impression, experience, etc. to persist or recur, or of an individual to continue a particular mental activity without the ability to shift easily to another at a change in stimulus". In Psychiatry terms it is ,the persistent and pathological repetition of a verbal or motor response, often seen in organic brain disease.’ http://www.yourdictionary.com/perseveration

Here is just one example of perseveration. I have deliberately cut this to three parts as "What"s that thing?’ gets annoying to read after a while. In real life though that question could have gone on for hours!