From Wikipedia, the free encyclopedia - View original article
Tangential speech is a communication disorder in which the train of thought of the speaker wanders and shows a lack of focus, never returning to the initial topic of the conversation. It is less severe than Logorrhea and may be associated with the middle stage in dementia. It is, however, more severe than circumstantial speech in which the speaker wanders, but eventually returns to the topic.
Some adults with right hemisphere brain damage may exhibit behavior that includes tangential speech. Those who exhibit these behaviors may also have related symptoms such as seemingly inappropriate or self-centered social responses, and a deterioration in pragmatic abilities (including appropriate eye contact as well as topic maintenance).